International Symposium on Advances in Nanoscience · International Symposium on Advances in Nanoscience October 25-26, 2010 Campus Garching Center for Nanotechnology and Nanomaterials

International Symposium on Advances in Nanoscience

October 25-26, 2010

Campus Garching

Center for Nanotechnology and Nanomaterials (ZNN) and TUM Institute for Advanced Study (IAS)

2 Advances in Nanoscience - Garching 2010

Content3 | Introduction

5 | Invited Talks

31 | Poster Presentations

77 | Useful Information

78 | List of Participants

ORGANIZERS

Nanosystems Initiative Munich and TUM Institute for Advanced StudyGerhard Abstreiter, Hendrik Dietz, Jonathan J. Finley, Dirk Grundler, Alexander Holleitner, Paolo Lugli, Friedrich Simmel, Martin Stutzmann

CONTACT

Irmgard Neuner (Offi ce Prof. Gerhard Abstreiter)Walter Schottky Institut (TU München)Am Coulombwall 3D-85748 GarchingTel: +49-(0)89-289-12771Fax: +49-(0)[email protected]

VENUE

TUM Institute for Advanced Study (IAS) and Center for Nanotechnology and Nanoma-terials (ZNN) of Walter Schottky Institut in Garching

The Symposium is hosted by

Advances in Nanoscience - Garching 2010 3

INTRODUCTION

The “International Symposium on Advances in Nanoscience” is the Inaugural Symposium for the new center for nanotechnology and nanomaterials (ZNN) at the TUM in Garching that was offi cially opened on July, 19th, 2010. After a fast planning phase and only one year of construction, the building is now almost fully operational. It offers 2000 square meters of offi ces and laboratory space with modern equip-ment for nanoscientists of various directions.

In the last few months, research groups have moved into the building and now start to work in several exciting areas of nanoscience, as they are also represented by the different sessions of this symposium – Quantum Nanosystems, Hybrid Nanosystems, Nano and Energy, and Bio-Nanoscience. These areas also represent the major research directions of the DFG funded Excellence Cluster “Nanosystems Ini-tiative Munich“ (NIM), where the ZNN researchers are heavily involved.

The ZNN is an extension of the well-known Walter Schottky Institute (WSI) that was founded in Gar ching over 20 years ago. The extremely successful activities of the WSI led to a continuous demand for more lab and offi ce space, a trend that was considerably reinforced by the success of the Excellence Cluster NIM. This triggered the plan for a new building fully devoted to nanoscience. The concept for the new building was developed by Gerhard Abstreiter (WSI) and co-workers and was jointly funded by the Bavarian State and the Federal Government.

While the main focus of the WSI still lies in semiconductor materials technology, in the ZNN modern nanofabrication techniques and research at the nano/bio interface will be more prominent. The ground fl oor will host a modern clean room facility for micro- and nanofabrication, and also instrumentation for the characterization of nanomaterials. The fi rst fl oor is devoted to cutting-edge optical and electronic experiments with solid state nanostructures, but also on hybrid nanosystems. The second fl oor contains “wet” labs and physical labs for research in bionanotechnology. Thus, the new building will be perfectly suited for internationally competitive, interdisciplinary research in nanoscience.


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TalksINVITED TALKS

Session 1: Quantum Nanosystems

Experiments on the ultimate two-dimensional electron system ...........................6Klaus von Klitzing

Graphene quantum circuits .....................................7Klaus Ensslin

Exploring and harnessing cavity-QED phenomena in single and few quantum dot photonic crystal nanostructures ......................8Jonathan Finley

Periodic Nanowire Structures................................10Erik Bakkers

Ga-assisted MBE grown GaAs nanowires and related quantum heterostructures for solar applications .............................................11Anna Fontcuberta i Morral

Session 2: Hybrid Nanosystems

Voltage-sustained self-oscillation of a nanomechanical electron shuttle .......................12Eva Weig

Cooper-pair splitter: towards an effi cient source of spin-entangled EPR pairs .....................13Christian Schönenberger

Pure spin current based spintronics in metallic nano-structures ....................................14Yoshichika Otani

Carbon nanostructures for quantum spintronics ........................................15Jörg Wrachtrup

Plasmonic control of elementary emitters ...........16Joachim Krenn

The perfect wave .....................................................17Achim Wixforth

Optoelectronic dynamics in hybrid nanoscale circuits ......................................18Alexander Holleitner

A Quarter Century of Quantum Dots: From Science to Practical Implementation ..........19Yasuhiko Arakawa

Session 3: Nano and Energy

„Black Silicon“: Nanotextured Silicon Surfaces for Photovoltaics ....................................20Martin Stutzmann

Role of Nanotechnology in Third Generation Photovoltaics ............................21Stephen Goodnick

Nanostructured organic and hybrid solar cells ....................................................22Lukas Schmidt-Mende

Heusler Compounds: Novel Materials for Energy Applications ..............23Claudia Felser

TiO2-Nanotubes in Energy Research ....................24Julia Kunze

Session 4: Bio-Nanoscience

Synthetic Biology of Cell Division .........................25Petra Schwille

DNA Nanotechnology for Protein Science ...........26Hendrik Dietz

The Bio-Electronic Synapse – Fusing Electronics with Molecular Biology ..........27Uri Sivan

Molecular Interactions on Dynamically Actuated Surfaces and in Artifi cial Nanopores ....................................28Ulrich Rant

Stochastic gene expression and the decisive role of noise in microbial genetic networks .........29Joachim Rädler

Nanoscale structures and molecular devices made from DNA ........................................30Friedrich Simmel


Talk

sExperiments on the ultimate two-dimensional electron systemKlaus v. Klitzing and co-workersMax Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany

The title of the symposium “Advances in Nanoscience” provokes a presentation about the thinnest two-dimensional electron system known as graphene. The presentation will sum-

marize own experiments on graphene mono- and bilayers (produced either by epitaxial growth or by exfoliation), including Raman experiments, magneto-transport results, TEM investiga-tions and ARPES data. The focus will be on transport measurements at low temperatures and strong magnetic fi elds.

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Graphene quantum dots and constrictions have been fabricated by mechanical exfoliation of graphene followed by electron beam lithography and dry etching. The single layer quality

of graphene has been checked by Raman spectroscopy. The electron hole-crossover can be investigated by linear transport experiments as well as using non-linear effects in three-terminal junctions. A variety of nanostructures such as graphene constrictions, graphene quantum dots and graphene rings have been realized. Of particular interest is the electron hole crossover in graphene quantum dots, spin states as well as the electronic transport through graphene double dots. The goal is to establish the peculiar consequences of the graphene bandstructure with its linear dispersion for the electronic properties of nanostructures.

Graphene quantum circuitsK. Ensslin

F. Molitor, J. Güttinger, S. Schnez, S. Dröscher, M. Hufner, A. Jacobsen, C. Stampfer, T. Ihn and K. Ensslin Laboratorium f. Festkörperphysik, ETH Zürich, Schafmattstr. 16, CH-8093 Zürich, Switzerland

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Solid-state cavity quantum electrodynamics (QED) systems offer a robust and scalable plat-form for quantum optical experiments and may even provide a route towards “on-chip”

photon based quantum information processing technologies. In particular, systems based on photonic crystal nanocavities containing one or more semiconductor quantum dots (QDs) have developed at a rapid pace over the past few years. A diverse range of experiments have been reported in both the weak1 and strong2,3,4 coupling regimes of the light matter interaction. In the weak coupling regime, the direction and rate of QD spontaneous emission can be tailored1

and novel “non-resonant” dot-cavity coupling mechanisms have been identifi ed due to cavity enhanced few-particle scattering5 and phonon mediated processes6. In the strong coupling re-gime, the QD strongly modifi es the cavity spectrum due to the coherent exchange of energy be-tween dot and the vacuum radiation fi eld. Several proposals for scalable quantum information networks and quantum computation rely on such strongly coupled systems and have begun to exhibit measurable quantum (photon number) effects in atomic systems7, superconducting circuit QED systems8 and QD cavity QED devices9.

In this talk, I will discuss recent optical studies of single QD photonic crystal nanocavities op-erating in both weak and strong coupling regimes of the light matter interaction. Topics that will be addressed include (i) the observation of highly effi cient single photon generation inside a photonic bandgap and nano-cavity, (ii) the identifi cation of a non-resonant coupling of the quantum dots into the cavity mode and an explanation of its fundamental origin, (iii) studies of phonon mediated coupling between a single dot and the nanocavity mode, (iv) investigations of the spectrum and dephasing of QD exciton polariton entangled states as a function of dot-cavity detuning as dynamical variables (incoherent pumping and lattice temperature) are varied and (v) the observation of coherent coupling between two quantum dots coupled to a common nanocavity mode. In contrast to most previous studies, where the QD-cavity spectral detuning is controlled by varying the lattice temperature or by the adsorption of inert gases at low tem-peratures, we have develop electro-optical tuning methods. This approach has enabled us to electrically control spontaneous emission2 and probe the emission spectrum in the strong cou-pling regime as a function dot-cavity detuning (Fig 1a) and external control parameters, such as the incoherent excitation level or the lattice temperature (Fig. 1b). Our studies provide insights into the nature of the strong coupling and processes responsible for dephasing of 0D-exciton polaritons.3 Most recently, in nanocavities containing two QDs that are simultaneously tuned into resonance with each other and the cavity mode we observe a triple peak at resonance (Fig. 2) - a signature of coherent cavity mediated coupling between the three quantum states.10

1 M. Kaniber et al. Phys. Rev. B77, 073312, (2008)2 A. Laucht et al., New J. Phys. 11, 023034 (2009).3 A. Laucht et al., Phys. Rev. Lett. 103, 087405 (2009).4 M. Nomura et al. Nature Physics, 6, 279, (2010)5 M. Winger et al. Phys. Rev. Lett. 103, 207403 (2009)6 U. Hohenester et al. Phys Rev. B80, 201311, (2010)7 K. M. Birnbaum et al. Nature 436, 87–90 (2005).8 D. I. Schuster et al. Nature 445, 515–518 (2007).9 D. Englund et al. Nature 450, 857, (2007)10 A. Laucht et al., Phys. Rev. B 82, 075305 (2010)

Exploring and harnessing cavity-QED phenomena in single and few quantum dot photonic crystal nanostructuresJonathan FinleyWalter Schottky Institut, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

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Fig. 1: (a) Plot of photoluminescence spectra for different applied bias voltages. The grey points cor-respond to the experimental data, while the black lines are fi ts to the theory. When the voltage is var-ied, the exciton transition is tuned through resonance with the cavity mode. The formation of a clear double-peak for zero detuning is an unambiguous sign for strong photon-matter interaction. (b) Reso-nant spectra for different excitation power densities as indicated in the graph. Again, the grey points correspond to the experimental data, while the black lines are fi ts to the theory. The observed splitting at zero detuning reduces for high excitation power densities until only a single broadened peak is visible (top spectrum).

We gratefully acknowledge fi nancial support of the DFG via SFB-63, the German Excellence Initiative via the Nanosystems Initiative Munich and the EU via SOLID.

Fig. 2: Comparison between the observed and calculated spectral functions of two quantum dots in resonance with one cavity mode, showing the excellent agreement between the measured spectrum (open circles) and the theoretical spectral functionfi tted to the data (black solid lines). The small arrows indicate the third peak in resonance which is proof for the coupling of three quantum states. The grey solid lines were calculated assuming that the two quantum dot states cannot coexist at the same time as it would be the case for e.g. exciton and charged exciton of the same quantum dot.

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Talk

sPeriodic Nanowire StructuresErik P.A.M. Bakkers

Erik P.A.M. Bakkers,1,2,3 Rienk Algra,3,4 Moira Hocevar,2,3 Magnus T. Borgström,3 George Immink,3 Bas Ketelaars,3 Lou-Fe Feiner,1,3 Willem J.P. van Enckevort,4 Elias Vlieg,4 Marcel A. Verheijen1,3

1 Eindhoven University of Technology, The Netherlands2 Delft University of Technology, The Nehterlands3 Philips Research Laboratories, Eindhoven, The Netherlands 4 Radboud University Nijmegen, The [email protected]

Semiconducting nanowires offer the possibility of nearly unlimited complex bottom-up design on intrawire and interwire level, which allows for new (opto-)electronic device concepts,

such as single-photon nanowire quantum dot emitters. On the interwire level, a lot of progress has been made on control of the nanowire position and appreciation of absolute growth rates. Here, we show recent advances on inducing periodicity on both intra- and interwire level, such to obtain 3-dimensional position control. The nanowire position is determined by that of the catalyst particle. We have developed a generic soft nano-imprint lithography process to fab-ricate arrays of metal particles [1]. From these structures nearly defect free arrays of InP and GaP nanowires have been grown. This approach gives in-plane periodicity. Next, we demon-strate control of the crystal structure of indium phosphide (InP) and gallium phosphide (GaP) nanowires by impurity dopants. More importantly, we demonstrate that we can, once we have enforced the zinc blende crystal structure, induce twinning superlattices with long-range order in the z-direction in the nanowires [2]. The spacing of the superlattices is tuned by the wire diameter and the zinc dopant concentration. These fi ndings have been quantitatively modelled based on the cross-sectional shape of the zinc-blende nanowires. [1] A. Pierret, M. Hocevar, S.L. Diedenhofen, R.E. Algra, E. Vlieg, E.C. Timmering, M.A. Verschuuren, G.W.G. Immink, M.A. Verheijen, E.P.A.M.

Bakkers. Nanotechnology 2010, 21, 065305[2] R.E. Algra, M.A. Verheijen, M.T. Borgström, L.F. Feiner, G. Immink, W.J.P. van Enckevort, E. Vlieg, E.P.A.M. Bakkers, Nature 2008, 456,

369

Figure 1. a,b) Scanning and transmission electron microscopy images of a nanowire with a twinning superlattice. c) SEM image of a periodic array of nanowire fabricated by nanoimprint lithography

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TalksGa-assisted MBE grown GaAs nanowires and related quantum heterostructures for solar applicationsA. Fontcuberta i Morral1,2,*

1 Laboratoire des Matériaux Semiconducteurs, Institute of Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland

2 Institute of Advanced Studies, Walter Schottky Institut und Physik Department, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

* Corresponding author: email: anna.fontcuberta-morral@epfl .ch

Nanowires represent model systems for studying a variety of low dimensional phenomena as well as building blocks for the future generation of nanoscale devices. The most exploit-

ed nanowire growth technique is the vapor-liquid-solid (VLS) method, which very often employs gold as a seed for the growth.

We present the method for growing GaAs nanowires by MBE without using gold as a catalyst. Along these lines, we will show how Molecular beam epitaxy offers a unique possibility for obtaining high purity and high quality materials. Additionally, it gives a great fl exibility for the fabrication of many types of nanowire heterostructures. We will present here how radial and axial heterostructures can be obtained and how this combination can be benefi cial for applica-tion in third generation solar cell designs. The optical and transport properties will be elucidated by means of luminescence, Raman spectroscopy and microscopy experiments realized on the same single nanowire.

Finally, the results are then applied to the realization of nanowire-based solar cells. The future of this research area will be briefl y discussed.

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Talk

sVoltage-sustained self-oscillation of a nanomechanical electron shuttleE. M. WeigCenter for NanoScience (CeNS) & Department of Physics, Ludwig-Maximilians-University Munich, [email protected]

In the past years high stress silicon nitride has received considerable interest as a robust and high Q material for nanomechanical systems. Here we present a nanomechanical charge

shuttle, which is a model system to investigate the coupling of electronic transport properties and mechanical degrees of freedom: A nanoscale metal island hosted by a resonator that is oscillating between two opposing electrodes can be used to mechanically transport charge and thus produce an electric current [1]. We have realized such an electron shuttle on a doubly clamped silicon nitride string subject to high intrinsic tensile stress. Typical devices consist of large arrays of shuttles with customized mechanical resonance frequencies in the range of 1 – 10 MHz that are shunted between the source and drain electrode. Frequency multiplexing is employed to individually address single shuttles.

Stable shuttling operation in the quasi-ohmic, high tem-perature regime could be demonstrated in an acoustically actuated shuttle at 20 K [2]. While acoustic operation im-plemented by a piezo transducer ensures complete decou-pling of the measured electrical signal from the drive and thus allows for clean transport measurements with linear current – voltage curves, it complicates low-temperature operation due to the inevitable dissipation of the piezo. De-spite ongoing island miniaturization to increase the shut-tle’s charging energy this has so far impeded the transition to the Coulomb blockade regime.

An alternative approach to effi cient nanomechanical sys-tems relies on self-oscillation, i.e. the generation of a pe-riodic vibration by a constant driving force. Self-sustained oscillation in nanomechanical systems has been observed in optomechanical systems driven by bolometric forces or radiation pressure, or in electromechanical systems with both external or internal feedback. Voltage-sustained self-oscillation of a nanomechanical charge shuttle has been theoretically predicted [1]. Here we present a nanomechanical electron shuttle operated solely by a DC-Voltage that is applied between source and drain [3]. After triggering the reso-nator via conventional actuation, the oscillation is sustained by repetitive charge reversal at the electrodes. Due to the minimal energy input of this driving scheme, operation at millikelvin temperatures becomes feasible. This may pave the way into the Coulomb blockade regime of discrete mechanical single electron shuttling.[1] L. Y. Gorelik et al., Phys. Rev. Lett. 80, 4526 (1998).[2] D. R. Koenig, E. M. Weig, J. P. Kotthaus, Nature Nanotechnology 3, 482 (2008).[3] D. R. Koenig, J. P. Kotthaus, E. M. Weig (in preparation).

Nanomechanical charge shuttle

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TalksCooper-pair splitter: towards an effi cient source of spin-entangled EPR pairsL. Hofstetter1, A. Kleine1, S. Csonka1,2, A. Geresdi2, M. Aagesen3, J. Nygård3, A. Baumgartner1, J. Trbovic1, and C. Schönenberger1

1 Department of Physics, University of Basel, Klingelbergstr. 82, CH-4056 Basel,Switzerland2 Department of Physics, Budapest University of Technology and Economics, Budafoki u. 6, 1111 Budapest, Hungary3 Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark

In quantum mechanics the properties of two and more particles can be entangled. In basic science pairs of entangled particles, so called Einstein-Podolsky-Rosen (EPR) pairs, play a

special role as toy objects for fundamental studies [1]. They provide such things as “spooky interaction at distance” [2], but they also enable secure encoding and teleportation and are thus important for applications in quantum information technology. Whereas EPR pairs of photons can be generated by parametric down conversion (PDC) in a crystal, a similar source for EPR pairs of electrons does not exists yet. In several theory papers, it has been suggested to use a supercondcutor for this purpose. The superconducting ground state is formed by a condensate of Cooper-pairs which are electron pairs in a spin-singlet state. Since there are many Cooper pairs in a metallic superconductor like Al, the main task is to extract Cooper pairs one by one and to split them into different arms. This has recently been demonstrated by two groups [3,4] using hybrid quantum-dot devices with both superconducting and normal metal contacts. The quantum dots were realized in semiconducting nanowires [3] and carbon nanotubes [3].

In this source, Cooper pairs are fi rst extracted from a superconducting contact onebe-one by tunneling. The real challenge lies in the separation of the two electrons. Since electrons are charged it has been proposed to use Coulomb repulsion to separate the two electrons [5]. This can be achieved by introducing two quantum dots. The enhancement of Cooper pair splitting follows, because the transfer of a Cooper pair through a single QD cost twice as much charg-ing energy than the transfer of two split electrons traversing the two arms separately. At low temperatures, this selection rule can lead to a 100% effi cient Cooper pair splitter [5]. The two recent experiments demonstrated a remarkably high effi ciency of up to 50 %. This has to be contrasted with optical PDC where effi ciencies of only < 10 − 6 are achieved. The new experi-mental results [3,4] are an important milestone in the realization of a solid-state source of en-tangled electron pairs. Such a source will make possible new experiments aiming at properties of solid-state devices beyond single electron physics. If one is able to convert electrons in the photons without loosing entanglement, this approach may even provide an effi cient source of EPR photons.[1] A. Aspect, P. Grangier, and G. Roger, Phys. Rev. Lett. 49, 91-94 (1982).[2] A. Einstein, B. Podolsky, N. Rosen, Phys. Rev. 47, 777-780 (1935)-[3] L. Hofstetter, S. Csonka, J. Nygard, and C. Sch¨onenberger, Nature 460, 906 (2009).[4] L.G. Herrmann, F. Portier, P. Roche, A. Levy Yeyati, T. Kontos, and C. Strunk, Phys. Rev. Lett. 104, 026801 (2010).[5] P. Recher, E. V. Sukhorukov, and D. and Loss, Phys. Rev. B 63, 165314 (2001).

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Talk

sPure spin current based spintronics in metallic nano-structuresY. Otania,b

a Institute for Solid State Physics, University of Tokyo, 5-1-5 Kahiwanoha, Kashiwa, Chiba 277-8581, Japanb RIKEN ASI, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan

The basic science for electronic devices aiming at manipulating the spin degree of freedom is spintronics, which provides a possible means to realize advantageous functionalities for spin

based recording and information processing. For such functions, the usage of spin-current, a fl ow of spin angular momentum, is indispensable. Thus establishing elemental technologies shown as building blocks for effi cient injection (input), manipulation, and detection (output) of spin-currents is a key for further advancement of spintronic devices. In this talk I will discuss the recent re-search progresses in terms of the spin-current induced phenomena in metallic nano-structures.

One of the spin-current induced phenome-na responsible for the input is the non-local spin injection where the spin accumulation is induced by the direct injection of spin po-larized current from a ferromagnetic metal to a non-magnetic metal, such as Cu or Ag. Fabricating clean interfaces or inserting MgO interface layers were recently found to increase the magnitude of spin accumu-lation in the non-magnetic metal tenfold [1, 2]. This enables us to switch the magneti-zation of a ferromagnetic nano-pillar by us-ing the pure spin current [2, 3]. Furthermore the spin transport along a 6 μm Ag wire is now possible in the lateral spin valve with MgO interface layers.

The spin Hall Effect (SHE) is also an interesting phenomenon where the spin-orbit interaction converts the spin-current into a charge current and vice versa, known as the “direct” and “in-verse” SHEs. The SHE was fi rst demonstrated on semiconductor systems by means of optical detection [4]. In diffusive metals, the electrical observation of the charge accumulation due to the inverse SHE was fi rst performed by using a nonlocal spin-injection in a lateral ferromagnetic / nonmagnetic Al metallic nano-structure [5]. This experiment was however successful only at low temperatures simply because of the long spin diffusion length, large enough with respect to the device dimensions, i.e. the small spin-orbit interaction of Al. Separately performed inverse SHE measurement using spin pumping technique ascertained that platinum with a large spin-orbit interaction, i.e. a short spin diffusion length of about 10 nm is a good candidate for further study of this sort [6]. Recent development of spin-current absorption technique enabled to detect elec-trically reversible SHE comprising the direct and inverse SHEs even at room temperature [7, 8]. More recently giant SHE in Au [9] was demonstrated by using the same method in Ref. [5].

This result opens up a new possibility to use normal metals with high spin-orbit interaction as spin-current sources operating at room temperature for the future spintronic applications.

Figure: Building blocks for a spin current circuit. Diagram shows possible spin current circuit, which exploits phenomena such as spin accumulation, spin transfer torque, and direct and inverse spin Hall effects.

[1] Y. Fukuma, et al., Appl. Phys. Lett. 97, 012507 (2010).[2] T. Yang, T. Kimura and Y. Otani, Nature Phys. 4, 851 (2008).[3] T. Kimura, Y. Oani, et al., Phys. Rev. Lett., 96, 037201 (2006).[4] Y. K. Kato, et al., Science, 306, 1910 (2004).[5] S. O. Valenzuela and M. Tinkham, Nature (London) 442, 176

(2006).

[6] E. Saitoh, et al., Appl.Phys. Lett. 88, 182509 (2006).[7] T. Kimura, Y. Oani, et al., Phys. Rev. Lett., 98, 156601 (2007).[8] L. Vila, T. Kimura, and Y. Otani, Phys. Rev. Lett., 99, 226604

(2007).[9] T. Seki, et al Nature Materials, 7, 125 (2008)

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TalksCarbon nanostructures for quantum spintronicsJ. Wrachtrup3rd Institute of Physics and Research Center SCoPE, Pfaffenwaldring 9, 70569 Stuttgart, Germany

Nanostructured carbon materials have become a versatile tool in modern electronic and quantum applications. Structures ranging from the well-known carbon nanotube over gra-

phene or carbon dots are well intensely studied for their novel charge transport and optical properties. Additionally carbon is outstanding because of its low spin orbit coupling. Hence, spins are well isolated form the lattice and form a valuable resource for quantum spintronics. The talk will describe how to engineer spin structures in diamond and other carbon structures. Precise read-out and control of spin states as well as coupling to external devices like optical and microwave cavities will be discussed.

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sPlasmonic control of elementary emittersJoachim R. KrennInstitute of Physics, University of Graz, Universitätsplatz 5, 8010 Graz, Austria, [email protected]

Surface plasmons are electromagnetic modes at the interface of a metal and a dielectric that can be focused to nanoscale volumes and that feature resonantly enhanced near fi elds.

Coupling plasmonic modes to quantum emitters as molecules or semiconductor nanocrystals is of specifi c interest, as this coupling can strongly alter both, the emitter excitation and emission rates. Here, we focus on the emission process that is governed by the photonic local density of states. This quantity can be tailored by controlling the geometry-dependent resonance fre-quencies of plasmonic nanostructures by lithographic means. On this basis we report emission rate engineering of fl uorophores [1], redirecting the energy fl ow in molecular resonance energy transfer [2] and refi ned insight in surface enhanced Raman scattering [3]. For better controlling the mutual position of plasmonic nanoparticles and molecules we apply lithographic methods to combine metal nanoparticles with molecule-doped polymer nanoparticles. We demonstrate that the local density of states of the plasmonic particles can be imaged by Moire patterns gen-erated by combining incommensurable regular arrays of both types of nanoparticles [4]. [1] S. Gerber et al, Phys. Rev. B 75, 073404 (2007)[2] F. Reil et al., Nano Lett. 8, 4128 (2008)[3] E. Le Ru et al., J. Phys. Chem. 112, 8117 (2008)[4] D. M. Koller et al., Phys. Rev. Lett. 104, 143901 (2010)

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TalksThe perfect waveAchim WixforthUniversity of Augsburg, Experimental Physics 1, Universitätsstr. 1, 86159 Augsburg, Germany

Many materials provide quite remarkable features in terms of their mechanical, electronic, magnetic or optical properties. Semiconductor structures and layered systems thereof for

example have revolutionized our daily life over the last few decades. Morover, if reduced to the nanometer scale, a wealth of novel properties and physical effects emerged that are partially already exploited technologically. However, some other materials have their own particular specialities that cannot be accomplished by semiconductors alone. By the deliberate realiza-tion of hybrid nanostructures consisting of semiconductors and piezoelectric oxides, or soft matter materials like supported membranes and elastomers we are able to create functional nanosystems that aim towards ‘the best of both worlds’ in such hybrids.

In my talk, I will present a few examples for functional hybrid nanosystems for photonic, elec-tronic and biological applications. By letting surface acoustic waves interact with these hybrids, novel tuneable functionalities can be created that are only possible by combining very different material classes.

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sOptoelectronic dynamics in hybrid nanoscale circuitsA.W. HolleitnerWalter Schottky Institut and Physik-Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany.

In order to fully exploit the potential of the diverse range of organic and inorganic nanosys-tems that exist, an extremely important step is the development of reliable electrical contacts

to connect them to the outside world and electrically manipulate and readout their properties. We investigate the possibility to build novel types of photo-electronic systems that consist of mixed organic and inorganic nanosystems such as nanocrystals [1], carbon nanotubes [2], semi¬conductor nanowires [3,4], and photosynthetic “light harvesting” proteins [5]. We explore the optoelectronic transport properties of single nanostructures to be probed by measuring the photocurrent response in an external electrical circuit. We focus on charge, energy, and heat transfer processes within the hybrid nanostructures [1-5], on excitonic optical excitations [6], as well as on so-called “ballistic” electron transport that occurs without energy relaxation [7]. In most recent experiments, we succeeded in resolving the real-time motion of photo-generated charge carriers in nanoscale circuits with a picosecond time resolution [8].

We thank our collaborators for very fruitful cooperations and the German excellence initiative via the “Nanosystems Initiative Munich (NIM)” for fi nancial support.

Photosynthetic protein covalently bound to carbon nano-tubes [5].

[1] M. A. Mangold, C. Weiss, M. Calame, A. W. Holleitner, Appl. Phys. Lett. 94, 161104 (2009).[2] B. Zebli, H. A. Vieyra, I. Carmeli, A. Hartschuh, J. P. Kotthaus, A. W. Holleitner, Phys. Rev. B 79, 205402 (2009).[3] S. Thunich, L. Prechtel, D. Spirkoska, G. Abstreiter, A. Fontcuberta i Morral, A. W. Holleitner, Appl. Phys. Lett. 95, 083111 (2009).[4] C. Ruppert, S. Thunich, G. Abstreiter, A. Fontcuberta i Morral, A.W. Holleitner, and M. Betz, Nano Lett. 10 (5), 1799 (2010).[5] S. M. Kaniber, M. Brandstetter, F.C. Simmel, I. Carmeli, A.W. Holleitner, J. of the Am. Chem. Soc. 132, 2872 (2010).[6] X. P. Vögele, D. Schuh, W. Wegscheider, J. P. Kotthaus, A. W. Holleitner, Phys. Rev. Lett. 103, 126402 (2009).[7] K.-D. Hof, F.J. Kaiser, M. Stallhofer, D. Schuh, W. Wegscheider, P. Hänggi, S. Kohler, J.P. Kotthaus, A.W. Holleitner, Nano Lett. accept.,

http://pubs.acs.org/doi/full/10.1021/nl102068v (2010).[8] L. Prechtel, S. Manus, D. Schuh, W. Wegscheider, A.W. Holleitner, Appl. Phys. Lett. 96, 261110 (2010).

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Talks

Following Esaki’s pioneering work on superlattices and quantum wells, the concept of quan-tum dots was proposed by Arakawa and Sakaki in 1982 for application to semiconductor la-

sers with the theoretical prediction of temperature insensitive threshold current characteristics. Full confi nement of electrons in the quantum dots has brought up unique features of artifi cial atoms, such as discrete energy states and correlation effects due to spin/charging effects. This has resulted in a wide variety of experimental investigations into semiconductor physics as well as device applications.

A successful demonstration of highly temperature-stable quantum dot lasers in 2004 by the University of Tokyo and Fujitsu [2] was led to the launch of a spin-off venture company called QD Lasers Corporation in 2006. In 2010, the quantum dot lasers have been delivered to a telecom commercial market. In addition to nanophotonic device applications, single or coupled quantum dots are promising for quantum information technologies, such as single photon emit-ters and quantum-bit devices, with manipulating single photon-electron interaction and quan-tum entangled states based on electron spins, charges, and nuclear spins.

For aiming at future establishment of “quantum mechanical engineering”, a national big project named Nano Quantum Information Electronics (NanoQuine) was started in 2006 in Japan. This is a joint project between the University of Tokyo and major electronics companies (NEC, Hi-tachi, Fujitsu, Sharp and QD laser). This project receives, as a 10 years’ project, the total bud-get of ~80 M$ from the government and corresponding matching funds from the companies. We started a new research center named Institute of Nano Quantum Information Electronics attached directly to the president of the University of Tokyo. The purpose of this project is to bring innovation in device and system technologies based on quantum dot and related nano-science. The project has already attained several signifi cant results such as highly temperature stable quantum dot lasers with 25 Gbps modulation, the fi rst transmission experiment of quan-tum keys over 50 km using quantum-dot single-photon source at 1.5 μm wavelength and the highest speed operation in both p- and n-MOS organic transistors.

In this presentation, prospects of quantum dot research for future innovation will be addressed including the effort of the Japanese government through the NanoQuine project. Moreover, I will also overview an additional national project, Photonics Electronics Convergence System Technology (PECST), which was selected as one of 30 projects in the framework of the pro-gram, Funding Program for World-Leading Innovative R&D on Science and Technology. We started the new project in collaboration with companies (NEC, Hitachi, Fujitsu, NTT, Oki, AIST) in March 2010, aiming at demonstrating a photonics system on LSI plat-form as well as ex-ploring innovative technologies including Si-based light sources. The total budget is 55M$ for 4years. The WSI-TUM is also one of the collaborating members for this project.

A Quarter Century of Quantum Dots: From Science to Practical ImplementationYasuhiko ArakawaHans Fischer Senior Fellow of TUM Institute for Advanced Study Institute for Nano Quantum Information Electronics, The University of Tokyo4-6-1 Komaba, Meguro, Tokyo 153-8505 [email protected]

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s„Black Silicon“: Nanotextured Silicon Surfaces for PhotovoltaicsSvetoslav Koynov, Martin S. Brandt, and Martin StutzmannWalter Schottky Institut, Technische Universität München, Garching, Germany

Effi cient anti-refl ection coatings are an important component of all high-effi ciency solar cells. Today, mainly anisotropic etching of Si(100) surfaces or of transparent conductive oxides

(for single crystalline Si and thin fi lm solar cells, respectively) as well as λ/4-Si3N -layers (for multicrystalline Si solar cells) are used in production. From a basic point of view, however, the ultimate broadband antirefl ection behavior can be achieved by a conical nanotexturing of the surface with feature sizes in the sub 100 nm range. Such a surface texture acts as an effec-tive medium with a continuos variation of the refractive index from air to that of the bulk solid, independent of the wavelength of the incident light. As no discontinuity of the refractive index occurs, the refl ectivity of such a textured surface is essentially zero. We describe how such a texture can be realized by a fast, self-organized chemical etch in all forms of silicon (single-, multi, nano-crystalline, and amorphous) and discuss the optical and electronic properties of such surfaces, as well as their implementation in solar cells. The possibility to transfer such a texture to other surfaces (glass substrates, GaN) will also be mentioned.

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TalksRole of Nanotechnology in Third Generation PhotovoltaicsStephen M. Goodnick Stephen M. Goodnick and Christiana Honsberg Solar Power Laboratory, Arizona State University, Tempe, AZ 85287-9309, USA

In the present talk, the impact of nanotechnology innovation on current photovoltaic technol-ogy trends is discussed, with a focus on the expected role that nanotechnology will have on

current fi rst and second generation solar production. In particular, the trend in Si production is towards ultrathin Si, thus reducing material cost, and increasing performance. However, in order to scale Si thicknesses to micron scale dimensions requires innovations in terms of opti-cal absorption and energy capture, which requires advancements in present cell design. Spe-cifi cally, so called ‘third generation’ nanotechnology based concepts of light trapping through nanoplasmonic arrays, carrier multiplication through up-down conversion, or multiple-exciton effects in quantum dots, intermediate bands, etc. can allow for scaling to thin dimensions while signifi cantly improving effi ciencies. Here we discuss several different approaches, including Si nanowires for reducing the effective volume of Si, through effi cient light trapping in junction nanowires, strain grown InGAs quantum dots for intermediate band applications, and Si nano-particles for multiexciton generation.

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Talk

sNanostructured organic and hybrid solar cellsLukas Schmidt-MendeLudwig-Maximilians University (LMU) Munich, Dept. of Physics and Center for NanoScience (CeNS), Amalienstr. 54, 80799 Munich, Germany

Morphology control is a key issue towards more effi cient organic solar cells. However, it is diffi cult to achieve the desired control in purely organic materials. In this presentation

several approaches towards control of nano-morphology in organic, hybrid and inorganic solar cells will be discussed. Nano-imprint methods can lead to nanostructured organic solar cells [1]. Metal-oxide nanostructures are used as template and combined with organic materials for hybrid solar cells [2]. Novel fabrication methods allow the controlled fabrication of structures in nano-meter size designed for solar cell applications. Also in inorganic solar cells the nano-structure can to increased photocurrent [3]. Recent results of the group will be discussed in this presentation.[1] G. Scarpa, A. Abdellah, A. Exner, S. Harrer, G. Penso-Blanco, W. Wiedemann, L. Schmidt-Mende, P. Lugli, IEEE Transactions on Nano-

technol., 10.1109/TNANO.2010.2048433, 2010[2] K. P. Musselman, G. J. Mulholland, A. P. Robinson, L. Schmidt-Mende, J. L. MacManus-Driscoll, Advanced Materials 2008, 20, 4470.[3] K. P. Musselman, A. Wisnet, D. C. Iza, H. C. Hesse, C. Scheu, J. L. MacManus-Driscoll, L.Schmidt-Mende, Advanced Materials 2010, DOI:

10.1002/adma.201001455

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TalksHeusler Compounds: Novel Materials for Energy ApplicationsClaudia FelserInstitute of Inorganic Chemistry, Johannes Gutenberg University Mainz, Mainz, Germany

In 1905 Fritz Heusler discovered that the compound Cu2MnAl is ferromagnetic, even though none of its elemental constituents are themselves magnetic. This remarkable material and

its cousins, a vast collection of more than 1500 compounds, are now known as Heusler and Half Heusler compounds. Surprisingly, the properties of many of the Heuslers can be forecast simply by counting the number of their valence electrons [1]. One sub-class of more than 250 Heus ler compounds are semiconductors. Recent potential for applications are in electronic devices and green energy. Their band gaps can readily be tuned from zero to ~4 eV by chang-ing their chemical composition. These materials have thus attracted attention as potential can-didates for both solar cell and thermoelectric applications. Indeed, excellent therxcmoelectric properties have recently been demonstrated with fi gure of merit higher the 1.4.[1] C. Felser, G. H. Fecher, and B. Balke, Angew. Chem. 46, 668 (2007) S

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sTiO2-Nanotubes in Energy ResearchCeline Rüdiger1, Silvia Leonardi1,2, Florian Wiesinger1, Odysseas Paschos1, Fabio Di Fonzo2, Andrea Li Bassi2, Ulrich Stimming1 and Julia Kunze1

1 I nstitute for Advanced Study (IAS) and Department of Physics E19, Technische Universität, München, Germany 2 Politecnico di Milano NEMAS - Center for NanoEngineered MAterials and Surfaces, Milano, Italy

Self-organized nanostructured oxides grown by optimized metal anodization have attracted remarkable interest in the past decades. Starting with the growth of nanoporous alumina

[1], this type of anodic oxide fi lms can nowadays be grown on various valve metals and their alloys using dilute fl uoride based electrolytes. Upon all valve metal oxides, nanotubular TiO2 on Ti [2,3] is among the most promising structures since it offers several interesting functional properties. The growth mechanism of nanotubular TiO2 layers was investigated in glycerol/NH4F electrolytes. At low water concentration, smooth side walls are obtained. A comparison of the length of these tubes and the charge density fl owing during the anodization process shows that in certain cases the tubes grow longer than expected i.e. with an effi ciency > 100%. This phenomenon may be explained by an oxide fl ow model [4,5,6].

While the semiconductive nature of TiO2 is crucial for many applications in fi elds such as bio-technology, photo-catalysis or dye-sensitized solar cells, the limited conductivity prevents an even broader and effi cient use in applications that require a fast electron transport, such as functional electrodes or electrocatalyst supports. For the use of titania as a catalyst support in electrocatalysis, it has to be made conductive and inert towards reoxidation in the electrolyte. This can be achieved by using a carbo-thermal reduction treatment converting the TiO2 into an oxy carbide compound (TiOxCy) that shows stable semimetallic conductivity [7].

We are currently exploring fl at and nanotubular TiOxCy as support material in electrocatalysis. After the deposition of an electrocatalytically active metal, like Pt or Pd, reactions such as al-cohol oxidation and oxygen reduction (ORR) will be studied. We will investigate the infl uence of the metal coverage, the particle thickness and shape, and the metal oxidation state on the catalytic activity for ORR and alcohol oxidation. The infl uence of the TiOxCy support will be studied by looking at different oxygen to carbon ratios.[1] H. Masuda, K. Fukuda, Science, 268 (1995) 1644.[2] V. Zwilling, M. Aucouturier, E. Darque-Ceretti, Electrochim. Acta 45 (1999) 921.[3] J.M. Macak, H. Tsuchiya, A. Ghicov, K. Yasuda, R. Hahn, S. Bauer, P. Schmuki, COSSMS (2007).[4] S. Berger, J.M. Macak, J. Kunze, P. Schmuki, Electrochem. Solid-State Lett. 11 (2008), C37.[5] D.J. LeClere, A. Velota, P. Skeldon, G.E. Thompson, S. Berger, J. Kunze, P. Schmuki,

H. Habazaki, S. Nagata, J. Electrochem. Soc. 155(9) (2008) C487-C494.[6] S. Berger, J. Kunze, P. Schmuki, D. LeClere, A. Valota, P. Skeldon, G. Thompson, Electrochim. Acta 54 (2009) 5942-5948.[6] R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y.Y. Song, J. Kunze, V.-L. Lehto, P. Schmuki, Angewandte Chemie Int. Ed.

(VIP Paper) 48 (2009) 7236.

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TalksSynthetic Biology of Cell DivisionPetra SchwilleBiophysics - Schwille Lab, Biotechnologisches Zentrum der TU Dresden (BIOTEC), Tatzberg 47-51, 01307 Dresden, Germany

In recent years, biophysics has accumulated an impressive selection of novel techniques to analyze biological systems with ultimate sensitivity and precision. Single molecule imag-

ing, tracking and manipulation have enabled us to unravel biological phenomena with unprec-edented analytical power, and to come closer to revealing fundamental features of biological self-organization. On the other hand, our knowledge about biological systems has in the era of genomics and proteomics become vast and impossible to fully comprehend. The power of physics has always been the reductionist approach, i.e. the possibility to defi ne an appropriate subsystem simple enough to be quantitatively modeled and described, but complex enough to retain the essential features of its real counterpart. Transferring this approach into biology has so far been extremely challenging, because most “modern” biological systems usually comprise so many modules and elements, many of them still awaiting to be functionally resolved, that it is a risky, and thus, often frustrating task to defi ne truly essential ones. Nevertheless, the strive for identifying minimal biological systems, particularly of subcellular structures or modules, has in the past years been very successful, and crucial in vitro experiments with reduced complexity can nowadays be performed, e.g., on reconstituted cytoskeleton and membrane systems. As a particularly exciting example for the power of minimal systems, self-organization of essential proteins of the bacterial cell division machinery could be shown in a simple assay, consisting of only two protein species, an energy source, and a membrane. In the In my talk, I will discuss some recent results of our work on membrane-based systems, using single molecule optics and biological reconstitution assays. I will further discuss the perspective of assembling a mini-mal system to reconstitute bacterial cell division.

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Talk

sDNA Nanotechnology for Protein ScienceHendrik Dietz

Dietz Lab, Physik Department, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

Scaffolded DNA Origami [1] is a molecular self-assembly method that enables folding a mul-tiple-kilobase ‘back-bone’ DNA molecule into complex nanoscale shapes by introducing

interactions between different segments on the backbone molecule. Interaction patterns are expressed by sets of synthetic ‘staple’ molecules that are added to the much longer backbone molecule. Based on this concept we have developed a general approach to the construction of custom three-dimensional shapes that can be conceptualized as creating custom-crossection bundles of DNA double helices [2] where the number, arrangement, and lengths of helices can be freely designed. We further found a way for building shapes that also twist and bend in de-sired ways [3]. Importantly, DNA origami retains spatial registry over each of thousands of DNA bases that are installed in a constructed shape.

Molecular self-assembly with DNA origami thus affords truly unique positional control on the nanoscale. Our current efforts are centered on taking advantage of DNA origami for building nanoscale “gadgets” for applications in the molecular biosciences. One of our main goals is to develop a toolbox for the quantitative study of protein-protein and protein-DNA interactions on the single molecule level.[1] PWK Rothemund: NATURE 2006[2] SM Douglas, H Dietz, T Liedl, B Hogberg, F Graf, W Shih: NATURE 2009[3] H Dietz, SM Douglas, W Shih: SCIENCE 2009

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TalksThe Bio-Electronic Synapse – Fusing Electronics with Molecular BiologyArbel Artzy-Schnirmana,b,c, Elad Broda,c, Dan Blatdd, Rami Fishlera,c, Dori Gertmanb, Ravit Orenb, Tova Waksd, Yoram Reitera,b, Itai Benhare, Zelig Eshhard, Uri Sivana,c a The Russell Berrie Nanotechnology Institute, b Biology, Technion – Israel Inst. of Technology, Haifa, Israelc Physics, Technion – Israel Inst. of Technology, Haifa, Israeld Biology, Weizmann Inst. of Science, Rehovot, Israele Biotechnology, Tel Aviv University, Tel Aviv, Israel

Manmade electronics and living systems are foreign to each other in all aspects. They are constructed from dissimilar materials using different strategies, employ different charge

carriers, and use distinctively different logic for their computation. The fusing of these two vast fi elds therefore poses major conceptual and practical challenges but at the same time holds great promise. Learning a lesson from biology where functional interfaces are realized through mutual recognition of two molecules we propose and demonstrate a generic approach to the integration of electronics with biology. In our bio-electronic synapse one of the recognizing molecules is replaced by an electronic device having two states while for the other molecule we choose an antibody selected in-vitro to discriminate between the two electronic states. Application of 0.6V to the device sets it in the “on” state where the antibody binds the device. A subsequent application of -0.6V to the same device turns it to the “off” state where the anti-body detaches from the device. The power of such an electrical control over recognition will be demonstrated by its implementation to the control of T-cell activation by fl ipping an electrical switch.

If time allows, the physics underlying the operation of our bio-electronic synapse will be ex-plained.

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Talk

sMolecular Interactions on Dynamically Actuated Surfaces and in Artifi cial NanoporesUlrich RantWalter Schottky Institute & Institute for Advanced Study, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

I will present two methods to analyze molecular interactions which rely on functionalities aris-ing from nano-scale dimensions.

The ‘switchSENSE’ principle is based on an electrically actuated bio-interface. DNA molecules are driven to oscillate (switch their conformation) on microelectrodes through the application of AC potentials. The switching behavior serves as a universal parameter to infer the molecu-lar state of the bio-interface and permits to detect the binding of target molecules (proteins or nucleic acids) to the layer. In addition to the quantitative analysis of ‘classical’ interaction parameters like affi nity constants or association/dissociation rates, previously inaccessible in-formation about the target molecule size and shape are obtained from a molecular dynamics analysis. The implications of the switching dynamics measurement for a novel type of on-chip protein analysis will be discussed, in particular with respect to the engineering of antibodies. Moreover, the application of the switchSENSE principle for the detection of a cancer associated single nucleotide mutation in the p53 gene is demonstrated.

Artifi cially engineered nanopores in solid state membranes constitute versatile and robust de-vices to examine nano-scale objects. Single molecules leave a characteristic footprint in the trans-membrane current when passing a single pore of nanometer dimensions. By placing individual molecular receptors inside the pore we are able to study the interaction time of bind-ing partners one-by-one. As a paradigm for stochastic sensing, we exemplarily analyze single protein interactions at hand of the NTA/His-tag affi nity system and demonstrate how the action of a competitive binder affects the association and dissociation constants. Moreover, we ad-vance the nanopore concept by introducing the pore-cavity-pore device, which consists of two nanopores forming the in- and outlets to a femto-liter volume, and demonstrate the electrically controlled injection, storage, and ejection of individual nano-objects. Furthermore, we employ the pore-cavity-pore structure to obtain experimental single-particle data on fundamental prob-lems like confi ned diffusion and the escape of nano-objects across entropy barriers.

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TalksStochastic gene expression and the decisive role of noise in microbial genetic networksJoachim O. RädlerFakultät für Physik, Ludwig-Maximilians-Universität München, Geschwister-Scholl-Platz 1, 80539 München, Germany

Molecular fl uctuations can cause signifi cant cell-to-cell variations in the phenotype of ge-netically identical bacterial populations. Gene regulatory networks, which determine the

cellular response to environmental signals, are subdued to noise at the molecular concentra-tion levels leading to broadened distribution in expression timing or in other cases bimodal expression profi les. We use green fl uorescent protein to record the protein expression at the single-cell level for the arabinose utilization system of E.coli and the quorum sensing system of Putida. The experimental outcomes are compared to stochastic models of the underlying gene-regulatory networks.

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Talk

sNanoscale structures and molecular devices made from DNAF. SimmelBiomolecular Systems and Bionanotechnology, Physics Department and ZNN/WSI, Technische Universität München, Am Coulombwall 4a, D-85748 Garching, Germany

The sequence-dependent molecular recognition properties of nucleic acid molecules such as DNA and RNA can be utilized for the programmable assembly of molecular nanostruc-

tures and nanodevices.

For instance, the recently developed “DNA origami technique” enables molecular assembly of two- and even three-dimensional nano-objects with almost arbitrary shape. Such structures can be used as a scaffold for the positioning of other nanoscale objects such as small mol-ecules, nanoparticles or proteins into specifi c arrangements. In addition to several examples for such assemblies, we will show how recently developed super-resolution microscopy tech-niques such as Blink Microscopy or STORM allow for an optical characterization of these sub-wavelength structures.

In addition to the realization of static nanostructures, one of the visions in the fi eld of molecular nanotechnology is the realization of nanoscale “machines” inspired by the dynamic molecular assemblies found in biological systems. In fact, DNA can be utilized to construct also dynamic nanostructures that are controllably driven through a series of distinct conformational states. One of the major goals in this area is the operation of artifi cial molecular devices in biological systems, where they may act as sensors or actuators in vivo.

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POSTER PRESENTATIONS

Quantum Nanosystems

Hybrid Nanosystems

High frequency tuning of photonic crystal nanocavity modes using surface acoustic waves .......................................................33D. A. Fuhrmann

Electrostatic control of the charge state of nitrogen-vacancy centers in diamond ..............34M. V. Hauf

Growth kinetics in position-controlled and catalyst-free InAs nanowire arrays on Si (111) grown by selective area molecular beam epitaxy .........................................35S. Hertenberger

Raman spectroscopy and electrical transport investigations of InAs nanowires grown on Si (111) by molecular beam epitaxy .................36N. Hörmann

Non-resonant feeding of photonic crystal nanocavity modes by quantum dot multi-exciton states .........................................37A. Laucht

Ultrafast photocurrent response of freely suspended graphene ...................................38L. Prechtel

Autocatalytic growth of GaAs nanowires on Si (111) by molecular beam epitaxy using different SiO2 templates ..............................39D. Rudolph

Spin-Orbit coupling effects in the quantum oscillatory magnetization of asymmetric InGaAs/InP quantum wells .....................................40B. Rupprecht

Dynamic carrier injection into individual self-assembled quantum dots controlled by surface acoustic waves ....................................41F. J. R. Schülein

Single material band gap engineering in GaAs nanowires .................................................42D. Spirkoska

Spatially resolved fl ow of ballistic electrons measured by quantized photocurrent spectroscopy ..........................................................43M. Stallhofer

Towards nuclear spin free qubits based on Si/SiGe heterostructures ..................................44A. Wild

Spatially resolved polarization dependent Raman spectroscopy and pressure induced resonant Raman on GaAs nanowires ...................45I. Zardo

Organic Functionalization of Group IV-Semiconductors .....................................46M. Auernhammer

Organized growth of bifunctional oligoarenes and organometallic complex linkers on semiconductor nanoscale devices .......................47A. Cattani-Scholz

Optoelectronic properties of two-dimensional gold nanoparticle arrays ........................................48B. Dirks

Spin waves in individual and periodic permalloy nanostructures ........................................................49G. Duerr

Graphene solution-gated fi eld effect transistor arrays for sensing applications .............................50L. Hess

AlGaN/GaN semiconductor biosensors for applications in radiation biophysics ...............51M. Hofstetter

Spin wave resonances in ferromagnetic thin fi lms prepared via atomic layer deposition ..........52R. Huber

A Bose-Einstein condensate coupled to a micromechanical oscillators ..........................53D. Hunger

Optomechanical coupling of ultracold atoms and a membrane ..........................................54M. Korppi

Photoconductance of a submicron oxidized line in surface conductive single crystalline diamond ................................................55M. Seifert

Polymer Brushes on Graphene .............................56M. Steenackers

Spatially resolved optoelectronic measurements of organic thin fi lm transistors ..............................57C. Westermeier


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Regulation of Cellular Signaling Pathways by Spatial Organization of Molecular Extracellular Matrix Cues .......................................61H. Böhm

Expanding the Scope of Single Molecule FRET with DNA Origami .........................................62C. Castro

Sensing applications of GaN-based devices........63J. D. Howgate

Organic Thin-Film Transistors for Applications in Radiation Biophysics .........................................64A.-L. Idzko

DNA Origami as a Molecular Platform for Bionanotechnology ..........................................65R. Jungmann

Towards studying equilibrium unbinding/binding transitions of single protein complexes under force – enabled by DNA Origami ................66F. Kilchherr

Fabrication and Electrical Characterization of a Pore-Cavity-Pore Device .................................67M. Langecker

DNA origami supports for the analysis of complex samples by singe-particle electron microscopy ...............................................68T. G. Martin

A Thermal Trap for DNA Replication .....................69C. B. Mast

Biochemistry on a leash ........................................70M. Schickinger

Synthetic Assembly of Non-Peptidic Ligands for Constructing αvβ3- and α5β1-Integrin based Fo-cal Adhesions .........................................................71A. Schwede

Single Molecules as Energy, Force, Friction and Structure Sensors .............................72F. Stetter

Single-Molecule Cut and Paste for Functional Assembly ..............................................73M. Strackharn

Analysis of proteins on a chip with the switchSENSE platform .....................................74R. Strasser

Protein Binding Assays in Biological Liquids using Microscale Thermophoresis ........................75C. J. Wienken

Formation of Nanoparticle Structures with a Combination of Protein and DNA Linkers .........76V. B. Zon

Nano and Energy

Bio-Nanoscience

Compact and Nanotubular TiO2 in Energy Research ................................................58C. Rüdiger

Investigation of the thermal conductivity of GaAs nanowires by Raman spectroscopy combined with laser heating..................................59M. Soini

Investigation of different interface morphologies in organic solar cells .....................60W. Wiedemann


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High frequency tuning of photonic crystal nanocavity modes using surface acoustic wavesD. A. Fuhrmann1,2, S. M. Thon3, H. Kim2, D. Bouwmeester3,4, P. M. Petroff2, A. Wixforth1 and H. J. Krenner1

1 Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany2 Materials Department, University of California, Santa Barbara, CA 93106, USA3 Physics Department, University of California, Santa Barbara, CA 93106, USA4 Huygens Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands

We propose and demonstrate high frequency dynamic modulation of localized optical modes of photonic crystal membrane (PCM) defect nanocavities employing surface acoustic

waves (SAWs). The mechanical deformation induced by SAW distorts the PCM periodicity and gives rise to pronounced modulation of the nanocavity mode. We probe the cavity line as a function of the local phase of the SAW and resolve a dynamic and periodic modulation with tuning speeds >1.5 GHz. We resolve amplitudes ∆λC > 2 nm corresponding to > 15 cavity lin-ewidths for the cavities (Q > 7000) studied without signifi cant degradation of the quality factor. These observations are found in excellent agreement with FDTD simulations for the same ca-vity design and realistic amplitudes < 2 nm. Our calculations show no resolvable redistribution of the fi eld distribution of the cavity mode making our technique attractive for both solid state cQED and cavity optomechanical systems.


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Electrostatic control of the charge state of nitrogen-vacancy centers in diamondM.V. Hauf1, M. Dankerl1, M. Stutzmann1, J.A. Garrido1, B. Grotz2, F. Reinhard2, B. Naydenov2, J. Wrachtrup2 and F. Jelezko2

1 Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany2 3. Physikalisches Institut, Universität Stuttgart, Pfaffenwaldring 57, D-70550 Stuttgart, Germany

Nitrogen vacancy defects (NV) in the diamond lattice have been extensively studied in the past for several reasons. NV centers can act as non-bleachable single photon emitters in

the visible range [1]. Furthermore, they exhibit extraordinary spin coherence times of T2 = 1.8 ms at room temperature, which makes them promising candidates for realizing quantum com-putation and communication. In this context it is of great interest to achieve electrostatic control over the charge state of the NV in diamond.

We have shown that by changing the surface termination from oxygen to hydrogen, the fl uo-rescence of the negatively charged NV (NV-) can be suppressed. This effect is attributed to the band bending that occurs at hydrogen-terminated diamond surfaces according to the transfer-doping model [2]. A two-dimensional hole gas is formed at the surface which leads to a deple-tion from electrons and therefore the NV centers are expected to be discharged to the neutral state NV0 or a positively charged state NV+. This is confi rmed by observing the quenching of the fl uorescence of NV centers located under the hydrogenated diamond surface. Furthermore, the charge in the subsurface region of hydrogen-terminated diamond can be controlled by us-ing an electrolyte gate electrode. We use this effect to achieve for the fi rst time an electronic control of the charge state of the NV centers in diamond, allowing us to switch the fl uorescence of NV centers on and off.

Self-consistent numerical simulations, where the single-band effective mass Schrödinger equa-tion is solved and coupled to the Poisson equation via the charge density, can reproduce the surface band bending and the concurrent control of the NV-fl uorescence.[1] T. Gaebel et al, Appl. Phys. B 82, 2 (2005)[2] F. Maier, M. Riedel, B. Mantel, J. Ristein, and L. Ley, Phys. Rev. Lett. 85, 16 (2000)


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Growth kinetics in position-controlled and catalyst-free InAs nanowire arrays on Si (111) grown by selective area molecular beam epitaxyS. Hertenberger*, D. Rudolph, M. Bichler, J. J. Finley, G. Abstreiter and G. KoblmüllerWalter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, GermanyCorresponding author e-mail: [email protected]

We report self-induced selective area epi-taxy (SAE) of well-oriented, free-stan-

ding InAs (111) nanowires (NWs) on Si (111) substrates by solid-source MBE. Utilizing lithographically defi ned SiO2 nanomasks on Si (111) with periodic hole patterns of specifi c diameters and pitches (Fig. 1a), SAE of InAs NWs was performed under As-rich growth conditions in a completely catalystfree fash-ion. Adjustment of the proper substrate tem-perature was necessary to achieve highly selective growth, where InAs NWs nucleated only in the predefi ned holes with very high yields of around 90 % (ratio of vertically grown nanowires versus total number of holes) (Fig. 1b).

Based on this scheme, we showed that the yield of vertically ordered NWs was indepen-dent of the interwire distance (pitch) and the initial growth stages as opposed to previous observations by chemical vapor phase growth methods.

Furthermore, we investigated three distinct growth series, i.e., by variation of (i) growth tem-perature at fi xed III/V-ratio, (ii) growth time for different pitches (interwire distance) and (iii) III/V-ratio at fi xed growth time, to derive the underlying growth kinetics in MBE–grown SAE InAs NWs. Figs. 1c,d show representative electron micrographs of InAs NWs grown from growth series (iii) with two different pitches (i.e., 500 nm - Fig. 1c and 250 nm pitch - Fig. 1d) and an As-fl ux twice as high as compared to NWs grown in Fig. 1b.

Most interesting, signifi cant size variation of the NWs was found depending critically on the pitch and growth time. Two growth regimes were identifi ed – (i) a competitive growth regime with shorter and thinner nanowires for narrow interwire distances, and (ii) a diffusion-limited growth regime for wider distances providing good estimates for the surface diffusion lengths. Surprisingly, despite these size-dependent effects the nanowire geometries remained unal-tered with uniform, al-most non-tapered morphologies even over large variation in nanowire density (~mid–106-109 cm-2 range).

In terms of material properties, X–ray diffraction further revealed that the NW arrays were pre-dominantly single-crystalline zincblende and further confi rmed the vertical (111) directionality with low crystal tilt by rocking curve widths ( scans) as low as ~0.6 °. These crystal properties are further corroborated by TEM and PL measurements and will also be presented. Our fi nd-ings demonstrate the capability to precisely tailor the position and size of well-oriented III–V semicon-ductor NWs through non-catalytic MBE selective area growth and provide an impor-tant step toward fully integrated, uniform vertical III–V nanowire array-on-Si devices.

Fig. 1 (a) AFM image of a patterned SiO2/Si(111) substrate. The diameter of the holes is 80 nm and the hole-to-hole distance (pitch) 2 μm. (b) SEM image of selectively grown InAs NWs on the template de-scribed in (a) with an As-BEP of 2.6*10-6 mbar. (c,d) InAs NWs grown with a higher As-BEP of 5.2*10-6

mbar and a pitch of 500 nm and 250 nm, respec-tively.


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III–V semiconductor nanowires (NWs) directly grown on Si substrate have gained a lot of interest in recent years, due to the potential for low-defect density high-performance nano-

structure devices on Si platform. Also, as a result of their low dimensionality they exhibit pe-culiar physical properties, very different from bulk materials. The epitaxial growth of InAs NWs on Si (111) by ultra-high purity molecular beam epitaxy (MBE) was recently demonstrated in our group [1,2] using different substrate preparation and templates. Morphological parameters such as NW length and diameter were infl uenced strongly not only by growth conditions, but also substrate preparation resulting in either self-assembled or site-selectively grown NWs.

We present here investigations of the lattice dynamics of such InAs NWs by Raman spectros-copy, which has proved to be a powerful tool to investigate the structural properties in a non-destructive way. Furthermore, we analyzed the electrical transport properties in specifi c sets of single NWs.

Raman investigations performed on ensembles of as-grown NWs showed an unexpected downshift of the transverse opti-cal (TO) phonon peak compared to the InAs bulk reference sample [3], as opposed to a slightly upward shifted longitudi-nal (LO) phonon peak (Fig. 1). Size effects were found to be negligible for the investigated range of NW diameters (~50 – 220 nm). All measurements were done excluding heating artifacts and phonon-plasmon coupling at the e-rich InAs sur-face.

Also, we have identifi ed the crystalline quality in dependence of growth conditions and substrate preparation method, based on the full width at half maximum values for the TO and LO phonon peak widths.

Polarization dependent Raman spectroscopy experiments were also carried out on single InAs NWs. We were able to resolve at least two different TO-like Raman peaks, i.e., a downshifted peak and another one near the bulk TO position. The observed split was induced by breaking of cubic symmetry, with several possible underlying effects being discussed in detail.

For electrical transport measurements, the InAs NWs were contacted using Ni/Au metallizat¬ion. Room temperature I-V characterization showed a linear Ohmic behavior with total resistances in the range of ~1.5 – 50 kΩ. Back-gate dependent measurements identifi ed an n-type behavior as expected due to intrinsic bulk electron conductivity and surface electrons arising from strong Fermi level pinning at the surface. Subsequently the NWs were cooled down to 4.2 K and 1.4 K. The I-V characteristics remained linear, but the measurements showed a slight increase of the resistance. Furthermore, a magnetic fi eld perpendicular to the NW growth axis was applied and magneto-resistance measurements were performed, which will be discussed in detail. [1] G. Koblmüller, S. Hertenberger, K. Vizbaras, M. Bichler, F. Bao, J.-P. Zhang, and G. Abstreiter, Nanotechnology 21, 365602 (2010).[2] S. Hertenberger, D. Rudolph, M. Bichler, J. J. Finley, G. Abstreiter, and G. Koblmüller, submitted to JAP (2010).[3] R. Carles, N. Saint-Cricq, J. B. Renucci, M.A. Renucci, and A. Zwick, Phys. Rev. B, 22, page 4804 (1980).

Raman spectroscopy and electrical transport investigations of InAs nanowires grown on Si (111) by molecular beam epitaxyN. Hörmann, E. Forster, S. Hertenberger, I. Zardo, D. Spirkoska, G. Koblmüller and G. AbstreiterWalter Schottky Institut, Physik Department, Technische Universität München, Am Coulombwall 3, D-85748 Garching, GermanyCorresponding author e-mail: [email protected]

Figure 1 Raman spectra of bulk InAs and an InAs nanowire with downshifted TO.


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Non-resonant feeding of photonic crystal nanocavity modes by quantum dot multi-exciton statesA. Laucht1, A. Mohtashami1, M. Bichler1, M. Kaniber1 and J. J. Finley1

1 Walter Schottky Institut, TU München, Am Coulombwall 3, D-85748 Garching, Germany E-mail: [email protected]

Photoluminescence studies of photonic crystal defect nanocavi-ties containing single quantum dots typically reveal intense,

highly correlated emission from the cavity mode, even when the discrete quantum dot transitions and mode are spectrally detuned (|∆E|>20 meV) [1,2,3]. Here, we show experimentally that such off-resonance emission from the cavity mode arises from multi exciton-continuum transitions during the cascaded emission from the dot. Experimentally, we track the temporal evolution of the emission spectrum and fi nd that the mode emission is temporally correlated with quantum dot multi-exciton emission but becomes much weak-er after the population in the dot reduces towards the single exciton level [4]. Our results lend further support to recent pump power de-pendent cross-correlation measurements [5] identifying such multi exciton-continuum transitions as being responsible for the emission from the cavity mode.

Photon cross-correlation measurements between the quantum dot and the far detuned cavity mode unambiguously prove that the cav-ity mode is fed by the same quantum dot. For small dot-cavity detun-ings (|∆E|<3 meV), acoustic phonon mediated dot - cavity coupling gives rise to cavity emission [6, 7]. However, for larger detunings acoustic phonon mediated coupling becomes ineffective and the cavity mode emission stems from optical transitions between higher excited multiexciton states and an energetically lower quasi continuum of multi exciton states [4]. This naturally results in several photons per excitation cycle at the cavity mode frequency, manifest-ing itself as Poissonian statistics of the cavity mode. At the same time, strong cross correlations exist in the conditional emission statistics of the quantum dot and cavity. These apparently contradictory observations are fully explained by our measurements. Time resolved luminescence spectra with sub nanosecond resolution show that the cavity mode is temporally correlated with the p-shell emis-sion from the quantum dot (see fi gure). In contrast, the s-shell emission is delayed due to the cas-caded emission process and only weak cavity mode emission is observed for low excitation levels. Power dependent time-resolved measurements lend further support to our interpretation and allow us to extract quantitative information about the strength of the off-resonant coupling. An understand-ing of this non-resonant dot-cavity coupling is of the utmost importance for low threshold quantum dot nano lasers, where it is expected to be the dominant source of optical gain.

We gratefully acknowledge fi nancial support of the DFG via SFB 631 B3, and the Nanosystems Initiative Munich.[1] Hennessy K, Badolato A, Winger M, Gerace D, Atatür M, Gulde S, Fält S, Hu E L, and Imamoglu A, Nature 445, 896 (2007) [2] Press D, Götzinger S, Reitzenstein S, Hofmann C, Löffl er A, Kamp M, Forchel A, and Yamamoto Y, Phys. Rev. Lett. 98, 117402 (2007)[3] Kaniber M, Laucht A, Neumann A, Villas-Bôas J M, Bichler M, Amann M-C, and Finley J J, Phys. Rev. B 77, 161303(R) (2007) [4] Laucht A, Kaniber M, Mohtashami A, Hauke N, Bichler M, and Finley J J, in course of preparation (2009)[5] Winger M, Volz T, Tarel G, Porolan S, Badolato A, Hennessy K J, Hu E L, Beverator A, Finley J, Savona V, and Imamoglu A, Phys. Rev.

Lett 103, 207403 (2009)[6] Hohenester U, Laucht A, Kaniber M, Hauke N, Neumann, A, Mohtashami A, Seliger M, Bichler M, Finley J J, Phys. Rev. B 80, 201311(R) (2009)[7] Suffczynski J, Dousse A, Gauthron K, Lemaître A, Sagnes I, Lanco L, Block J, Voisin P, and Senellart P, Phys. Rev. Lett. 103, 027401 (2009)

Figure – Typical time resolved emission spectra recorded from a single dot nanocavity with |∆E|~16meV. Strong emis-sion is observed from the cavity mode in the fi rst 1-2ns, becom-ing much weaker as the excita-tion level in the system reduces toward the single exciton level.


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Ultrafast photocurrent response of freely suspended grapheneL. Prechtel1, L. Song2, D. Schuh3, W. Wegscheider3 and A.W. Holleitner1

1 Walter Schottky Institut and Physik-Department, Technische Universität München, 85748 Garching, Germany.2 Center for NanoScience (CeNS), Ludwig-Maximilians-University, Geschwister-Scholl-Platz 1, 80539 Munich, Germany.3 Institut für Angewandte und Experimentelle Physik II, University Regensburg, Universitätsstrasse 31, 93040 Regensburg, Germany

Recently, photocurrent generation at the interface between a mono- and a bi-layer of gra-phene has been attributed to the photo-thermoelectric effect [1]. Even though there are

indications that this effect is also accountable for the photocurrent generation at a graphene-metal interface, there is still debate whether intrinsic fi elds (similar to those in Schottky-contacts [2]) are separating the optically excited charge carriers.

We address these questions by a novel ultrafast photocurrent spectroscopy [3], which is based on a common pump-probe technique [4]. The experimental setup with a picosecond time-reso-lution will be introduced, and fi rst results of the time-resolved photocurrent of freely suspended graphene will be shown. We will discuss both the photo-thermoelectric effect and intrinsic fi elds at graphene-metal interfaces, as well as charge carrier relaxation effects by THz-generation within the graphene.

We acknowledge fi nancial support by the DFG excellence initiative “Nanosystems Initiative Munich” (NIM), the DFG project HO 3324/2 and Ho 3324/4, and the Center for NanoScience (CeNS) in Munich.1. X. Xu, N. M. Gabor, J. S. Alden, A. M. van der Zande, and P. L. McEuen, Nano Lett. 10, 562-566 (2010). 2. S. Thunich, L. Prechtel, D. Spirkoska, G. Abstreiter, A. Fontcuberta i Morral, and A. W. Holleitner, Appl. Phys. Lett. 95, 083111 (2009). 3. L. Prechtel, S. Manus, D. Schuh, W. Wegscheider and A. W. Holleitner, Appl. Phys. Lett. 96, 261110 (2010).4. D.H. Auston, IEEE J-QE 19, 639 (1983).


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Autocatalytic growth of GaAs nanowires on Si (111) by molecular beam epitaxy using different SiO2 templates Daniel Rudolph1, Simon Hertenberger1, Xiaodong Wang1,2, Watcharapong Paosangthong1, Max Bichler1, Gerhard Abstreiter1, Jonathan J. Finley1 and Gregor Koblmüller1

1 Walter Schottky Institut, Technische Universität München, Garching, Germany; and2 Pohl Institute of Solid State Physics, Tongji University, Shanghai, P. R. China

Corresponding author e-mail: [email protected]

Due to their peculiar geometry semiconductor nanowires (NWs) are highly promising for the realization of future optoelectronic and quantum devices. The enhanced lateral strain

relaxation allows the heteroepitaxial integration of highly lattice–mismatched systems, such as III-V semicon-ductor NWs, into established silicon (Si) technologies. However, the growth of high quality GaAs NWs with low defect densities, low impurity incorporation and superior electronic properties re-mains a major challenge since GaAs NWs are mostly grown by vapor-liquid-solid (VLS) processes using foreign catalysts, such as gold (Au). Au forms unwanted deep level traps in semiconductors and, thus, a self-catalyzed Ga-assisted VLS growth method was developed at our institute to grow gold-free GaAs NWs on GaAs substrates [1,2].

In this study, we investigated the autocatalytic growth of GaAs NWs on Si (111) grown by ultra–high purity solid source MBE. Three different kinds of substrate templates were used, namely Si (111) coated with (a) an ultrathin layer of amorphous SiOx, (b) an ultrathin layer (~2nm) of thermal SiO2, and (c) a layer of thermal SiO2 with periodic hole patterns defi ned by electron beam lithogra-phy and reactive ion etching (RIE). Scanning electron microscopy (SEM) con-fi rmed that growth on the former two substrates resulted in random self-assembled formation of vertical GaAs NWs along the <111> direction with an average area density of ~108cm-2, while the latter resulted in site-selective growth of NWs [cf. Fig. 1(a)] with a predetermined area-den-sity (107–108cm ). For the site–selectively grown NWs we have further investigated the effect of growth temperature and V/III ratio on the vertical NW growth yield and growth selectivity. The results indicate a narrow growth window for optimum NW growth.

SEM images revealed a clear droplet at the apex of the NWs indicating that growth is mediated by the VLS mechanism. This was confi rmed by in-situ studies of the nucleation dynamics us-ing refl ection high energy electron diffraction (RHEED). The time evolution of the RHEED Bragg spot intensity [Fig. 1(b)] revealed a pro-nounced intensity decrease and delay of NW growth with respect to the exposure to the Ga fl ux. This delay was found to depend on the V/III ratio and was attributed to the initial for-mation of Ga droplets on the substrate.

The structural quality of the grown GaAs NWs was investigated by high resolution x-ray dif-fraction (HRXRD). The epitaxial relationship between NWs and Si substrate was confi rmed and the dominant refl ections were found for zinc blende (ZB) (111) GaAs (2θ=27.3°) and Si (111) (2θ=28.4°). Optical characterization of single NWs via photoluminescence spectroscopy revealed further information about the crystal structure: For high V/III ratio (~5) a pure ZB struc-ture was found, while for lower V/III ratio (<2) a mixed crystal structure consisting of ZB and wurtzite phases was observed. This is in good agreement with earlier fi ndings for GaAs NWs grown on GaAs substrate [3].[1] A. Fontcuberta i Morral et al., Appl. Phys. Lett. 92, 063112 (2008)[2] C. Colombo et al., Phys. Rev. B 77, 155326 (2008)[3] D. Spirkoska et al., Phys. Rev. B 80, 245325 (2009)

Figure 1 (a) SEM image of a GaAs NW grown site-selectively on Si(111) using a patterned SiO2 mask, (b) Time evolution of RHEED intensity shows a de-lay between exposure to Ga and NW growth.


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Spin-Orbit coupling effects in the quantum oscillatory magnetization of asymmetric InGaAs/InP quantum wellsB. Rupprecht1,*, Ch. Heyn2, H. Hardtdegen3, Th. Schäpers3, M.A. Wilde1 and D. Grundler1

1 Lehrstuhl für Physik funktionaler Schichtsysteme, Physik Department, Technische Universität München, James-Franck-Straße 1, D-85747 Garching bei München, Germany

2 Institute of Applied Physics, Jungiusstraße 11, D-20355 Hamburg, Germany3 Institute for Bio- and Nanosystems (IBN-1) and JARA Jülich-Aachen Research Alliance, Research Centre Jülich GmbH,

D-52425 Jülich, Germany* B. Rupprecht, e-mail: [email protected], Tel: +49-89-289-12409, Fax: +49-89-289-12414

In 1984, Bychkov and Rashba proposed in a semi-nal paper [1] to measure the magnetic suscepti-

bility and the de Haas-van Alphen (dHvA) effect to observe and quantify the spin splitting induced by spin-orbit interaction (SOI) in a structure inver-sion asymmetric two-dimensional electron system (2DES). At low temperature, the magnetization M = -∂U/∂B refl ects in particular the evolution of the ground state energy U with the magnetic fi eld B. For over two decades, the predicted beating pattern in the quantum oscillatory behavior of M has not been observed experimentally due to the experimental challenge posed by the detection of the small mag-netic moment associated with the low number of charge carriers. Instead, beating patterns in the magnetoresistance R(B) of a 2DES were eval-uated to explore Rashba type SOI [2]. Recently, cantilever magnetometers using the torque τ = M × B have been proven to be very powerful to study 2DES magnetization [3,4]. The bea-ting pattern in M(B) was detected for a high-mobility 2DES in an AlGaAs/GaAs heterostructure. High tilt angles δ between the sample normal and the external fi eld were used to enhance the torque [5]. Here, we report the experimental observation of SOI induced beating patterns in M in a nearly perpendicular magnetic fi eld B using cantilevers. We address M of a 2DES in asymmetric InGaAs/InP quantum wells [6]. We observe a pronounced beating pattern below 1 T. The magnetization data allow for a quantitative modeling based on the theory outlined in Ref. [7]. By this means we extract the Rashba coeffi cient αR as well as the band structure pa-rameters such as the effective mass m*, Lande factor g* and the Landau level broadening Γ. In particular the full fi eld dependence of the total spin splitting γ(B) is obtained. This goes beyond the evaluation of γ from beat nodes in R(B) where only special fi eld positions are addressed. We will compare our results with simulations where we consider SOI in, both, perpendicular and tilted fi elds.

We thank D. Heitmann for continuous support and K. Groth for technical help. We gratefully ac-knowledge fi nancial support by the DFG via the German Excellence Cluster “Nanosystems Ini-tiative Munich (NIM)” as well as the SPP 1285 Halbleiter-Spintronik via Grant No. GR1640/3.[1] Y. A. Bychkov and E. I. Rashba, J. Phys. C 17, 6039 (1984)[2] J. Nitta, T. Akazaki, H. Takayanagi, and T. Enoki, Phys. Rev. Lett. 78, 1335 (1997)[3] M.A. Wilde, J.I. Sprinborn, O. Rösler, N. Ruhe, M.P. Schwarz, D. Heitmann, and D. Grundler, Phys. Stat. Sol. (b) 245, 344 (2008)[4] A.C. Bleszynski-Jayich, W.E. Shanks, B. Peaudecerf, E. Ginossar, F. von Oppen, L. Glazman, J.G.E. Harris, Science 326, 272 (2009)[5] M. A. Wilde, D. Reuter, Ch. Heyn, A. D. Wieck, and D. Grundler, Phys. Rev. B 79, 125330 (2009)[6] V.A. Guzenko, Th. Schäpers, and H. Hardtdegen, Phys. Rev. B 76, 165301 (2007)[7] W. Zawadzki, P. Pfeffer, Physica E 13, 533-537 (2002)

Fig. 1: Magnetization measured at 0.03 K (symbols), compared to theoretical modeling (line).


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Dynamic carrier injection into individual self-assembled quantum dots controlled by surface acoustic wavesFlorian J.R. Schülein1, Dirk Reuter2, Andreas D. Wieck2, Achim Wixforth1 and Hubert J. Krenner1

1 Lehrstuhl für Experimentalphysik I, Universität Augsburg, Universitätsstraße 1, 86159 Augsburg, Germany2 Lehrstuhl für Angewandte Festkörperphysik, Ruhr-Universität Bochum, Universitätsstraße 150, 44780 Bochum, Germany

We investigate the emission of single In(Ga)As/GaAs quantum dots (QDs) under the infl u-ence of surface acoustic waves (SAWs). Carriers are generated by a pulsed diode laser

(t < 100 ps) actively phase locked to the SAW. The SAW (f = 490 MHz) induces a switching of the QD emission from one single peak without SAW to three characteristic emission lines in the time-integrated spectrum with a SAW applied (cf. Fig 1(a)) [1]. By tuning the relative phase be-tween laser excitation pulse and SAW, we observe a pronounced intensity modulation of these three peaks with the fundamental period of the SAW (cf. Fig 1(b)) explained by acoustically driven carrier injection and conveyance which is less effi cient for holes. In addition, we observe a weaker modulation with the double period explained by electron tunneling out of the QD (two maxima per cycle) triggered by strong piezoelectric fi elds induced by the SAW.[1] S. Völk et al., Nano Letters 10 3399-3407 (2010), doi:10.1021/nl1013053


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Single material band gap engineering in GaAs nanowiresD. Spirkoska1,*, A. Efros2, S. Conesa-Boj3, J. Arbiol3, J. R. Morante3, A. Fontcuberta i Morral1,4 and G. Abstreiter1

1 Walter Schottky Institut, Technische Universität München, 85748, Garching, Germany2 Naval Research Laboratory, Washington, DC 20375, USA3 TEM-MAT, Servies Cientifi cotècnics, Universitat de Barcelona, Barcelona, CAT, Spain4 Laboratoire des Matériaux Semiconducteurs, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland* D. Spirkoska, e-mail: [email protected], Tel: +49-89-289-13873, Fax: +49-89-289-12704

Semiconducting nanowires are rapidly developing research fi eld with many possibilities for implementation in the next generation opto-electronic devices. Additionally, they represent

important platform for studying fundamental physical phenomena, generally not accessible in bulk materials. One striking example is the existence of the wurtzite (wz) crystal structure in III-V compounds, which have only zinc-blende (zb) structure in the bulk form. Their nanowire counterparts can grow with pure zb structure as well, but also with pure wz or a mixture of both. Due to the different band gaps of the wz and the zb structure, as theoretically predicted [1], nanowires with mixed wz/zb structure offer unique possibility for band gap engineering with only one material. In this work we investigated the optical properties of GaAs nanowires with a mixed wz/zb structure, with special accent on the polarization properties of the emitted light.

GaAs nanowires were grown using the Ga assisted Molecular Beam Epitaxy growth technique [2]. By varying the As pressure during the growth the crystal structure of the nanowires can be changed from pure zb to a mixture of zb and wz, evidenced by high resolution transmission electron micros-copy (HRTEM) (see Figure 1 a)) [3]. This enables the formation of quantum wells (QW) along the growth direction of the nanowires, with electrons confi ned in the zb region and holes confi ned in the wz region. A typical photoluminescence (PL) spectrum from one nanowire exhibiting a variety of QWs is presented on Figure 1 b). The polarization properties of the emitted PL are depending from the splitting between the heavy holes (hh) and light holes (lh) levels in the wz GaAs. The PL emis-sion at 4.2 K is polarized perpendicular to the nanowire growth direction in most of the investigated nanowires, indicating that the heavy hole level is the ground state. With increasing the temperature we still observe perpendicular polarization of the emitted light (though with decreased polariza-tion ratio), pointing out a relatively large splitting between hh and lh levels (Figure 1 c)). To explain these experimental fi ndings we developed a theoretical model that enabled us to extract some fundamental parameters of the wz GaAs from our measurements such as the splitting between the heavy hole and light hole states.[1] M. Murayama and T. Nakayama, Phys. Rev. B 49, 4710 (1994).[2] D. Spirkoska, C. Colombo, M. Heiss, G. Abstreiter and A. Fontcuberta I Morral, J. Phys.: Condens. Matter. 20, 454225 (2008).[3] D. Spirkoska, J. Arbiol, A Gustafsson et al. Phys. Rev. B, 80, 245325 (2009).

Figure 1. a) HRTEM image from GaAs nanowire exhibiting both zb and wz crystal structure. b) PL spectrum from a GaAs nanowire exhibiting a mixed wz/zb structure. c) Polarization dependence of the emission at E=1.483 eV.


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Spatially resolved fl ow of ballistic electrons measured by quantized photocurrent spectroscopyK.-D. Hof1, F. J. Kaiser2, M. Stallhofer3, D. Schuh4, W. Wegscheider4,5, P. Hänggi2, S. Kohler2,6, J. P. Kotthaus1 and A. W. Holleitner3,*1 Fakultät für Physik and Center for NanoScience (CeNS), Ludwig-Maximilians-Universität München, Germany2 Institut für Physik, Universität Augsburg, Germany3 Walter Schottky Institut and Physik Department, Technische Universität München, Garching, Germany4 Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany 5 Laboratorium für Festkörperphysik, HPF E 7, Eidgenössische Technische Hochschule Zürich, Switzerland6 Instituto de Ciencia de Materiales de Madrid (CSIC), Madrid, Spain* A. W. Holleitner, email: [email protected], Tel: +49-89-289-12775, Fax: +49-89-289-12704

Quantum point contacts (QPCs) have re-cently been exploited in very sensitive

detection schemes to quantify charge and spin states in nanoscale circuits and to image the coherent charge fl ow in two-dimensional electron gases (2DEGs) [1]. Here, we demon-strate the use of GaAs-based QPCs to spatial-ly resolve the ballistic fl ow of photo-generated electrons in a 2DEG [2]. To this end, electron-hole pairs are optically generated in a 2DEG by focused interband laser excitation at typi-cally 1.552eV with 76 MHz repetition rate. The resulting optical beam induced current (OBIC) through an adjacent QPC is measured with radio frequency lock-in detection as a function of the laser spot position (see scheme in Figure 1). We observe that photo-generated electrons can ballistically propagate across several microm-eters, before they tunnel through the QPC (Figure 2). As will be discussed in the presentation, the transmission of photo-generated electrons through the QPC is governed by the quantized energy and momentum values of the electron modes in the QPC. Hereby, the measured pho-tocurrent across the QPC exhibits characteristic quanti-zation steps.[1] M. A. Topinka, B. J. LeRoy, S. E. J. Shaw, E. J. Heller, R. M. Westervelt, K. D. Maranowski, and A.C. Gossard, Science 289, 2323-2326 (2000).[2] K.-D. Hof, F. J. Kaiser, M. Stallhofer, D. Schuh, W. Wegscheider, P. Hänggi, S. Kohler, J. P. Kotthaus, and A. W. Holleitner, Nano Lett., article

ASAP, publication date (Web): September 20, 2010


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Towards nuclear spin free qubits based on Si/SiGe heterostructuresA. Wild1 , J. Sailer1, K.M. Itoh4, E. E. Haller5, G. Abstreiter1, S. Ludwig3 and D. Bougeard1,2

1 Walter Schottky Institut, Technische Universität München, Germany2 Institut für Experimentelle und Angewandte Physik, Universität Regensburg, Germany3 Fakultät für Physik, Ludwig-Maximilians-Universität, Germany4 Department of Applied Physics and Physico-Informatics, Keio University, Japan5 Lawrence Berkeley National Laboratory, Materials Sciences Division, USA

Coupled quantum dots (QD) are presently intensely investigated as possible spin

qubits for quantum information processing (QIP). The electron spin coherence time in the curently most advanced GaAs based sys-tems is limited by the hyperne interaction of a conned electron with the many nuclear spins of the surrounding host crystal. Using Silicon (Si) as the host material oers a promising alterna-tive route towards solid state based QIP. For Si in its natural isotopic composition, substan-tially longer decoherence times are expected compared to GaAs as a result of reduced hyperne interaction and weak spin-orbit cou-pling. The possibility of isotopic purication of the Si crystal which contains no nuclear spins promises even superior coherence properties for electron spins.

We chose strained Si in SiGe as host material for conning electrons. This approach enables high electron mobilities and allows for isotopic engineering of the host crystal. By using single crystals enriched in certain isotopes as source materials in our molecular beam epitaxy (MBE) system we are able to create virtually nuclear spin free hosts [1] or to decorate the host crystal lattice with a variable concentration of nuclear spins to investigate the in uence on qubit deco-herence for prospective quantum dot circuits.

We have established the Si/SiGe heterostructure development and processing of two-dimen-sional electron gases (2DEG) and devices suitable for the denition of coupled QDs. The 2DEG densities can be tuned via front and backgates from 1 to 5·1011 cm-2. Thereby we achieve 2DEG mobilities in the range of 30,000 – 100,000 cm2(Vs)-1 for Si/SiGe in its natural isotopic composition and 10,000 – 40,000 cm2(Vs)-1 for 28Si/SiGe 2DEGs. Based on these 2DEGs we have already dened rst double QDs. Here we present rst characterization measurements of electrostatically dened double QD devices in natural Si. Full tunability of our double QDs is shown, including transport and charge spectroscopy. Preliminary pulsed-gate measurements demonstrate the suitability of our devices for coherent spin experiments and as spin qubits. Our rst double QD devices dened in 28Si 2DEGs are currently under investigation. These samples will allow coherent experiments on spin qubits in a nuclear spin free environment.[1] J. Sailer et al., Phys. status solidi RRL 3, 61 (2009)

Figure 1: Charge stability diagram, gate design of double quantum dot device and Si/SiGe heterostruc-ture layout.


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Spatially resolved polarization dependent Raman spectroscopy and pressure induced resonant Raman on GaAs nanowiresI. Zardo1,*, S. Conesa-Boj2, E. Uccelli1,3, F. Peiro2, Y. Xiang1, J. R. Morante2, J. Arbiol4, G. Abstreiter1 and A. Fontcuberta i Morral1,3

1 Walter Schottky Institut, Physik Department, Technische Universitaet Muenchen, Am Coulombwall 3, D-85748 Garching, Germany2 Departament d’Electrònica, Universitat de Barcelona, E-08028 Barcelona, CAT, Spain3 Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne,

Switzerland4 ICREA Research Professor at Institut de Ciència de Materials de Barcelona, CSIC, 08193 Bellaterra, CAT, Spain* Corresponding author: email: [email protected]

Semiconductor nanowires will play an important role in several areas of nanotechnology, such as electronics, sensing and energy conversion. The functional properties of nanowires

are infl uenced by different factors, the structure being one of the most determining. Spatially resolved Raman spectroscopy is a non-destructive technique used for the structural character-ization of materials, which enables to determine the crystalline phase and presence of strain.

In this work, the structural properties of gallium arsenide nanowires have been studied. The structural homogeneity of the nanowires is studied by spatially resolved Raman spectroscopy, and the obtained results are compared with Transmission Electron Microscopy measurements. The GaAs nanowires present a mixture of zinc-blende and wurtzite structure [1,2]. The Ra-man selection rules are determined (see Figure 1) and strain related effects underlined [3]. The E1-A1 splitting due to anisotropy of the crystal in wurtzite GaAs nanowires was found. The activation of the LO and SO modes was attributed to the presence of faceting on the nanowire sidewall.

We present also light scattering experiments on zinc-blende GaAs nanowires under hydrostatic pressure up to 20 GPa with a Diamond Anvil Cell. The applied hydrostatic pressure drives the tuning of the direct E0 nanowire band gap with respect to the excitation energy, leading to reso-nant Raman scattering. The dispersion of the Raman cross section of the TO, of the forbidden LO and second or higher order scattering processes has been measured at various pressures. The obtained results indicate a different response of the nanowires with respect to the bulk. The resonance profi le of the 2LO mode suggests a stronger Fröhlich coupling. The Grüneisen parameters were also found to be different from those obtained from bulk GaAs. Finally, there is evidence for a structural transition for P > 16 GPa.

This work shows that Raman spectroscopy of individual nanowire is a powerful technique for revealing the structural properties of nanostructures such as nanowires.[1] C. Colombo et al., Phys. Rev. B 77, 155326 (2008)[2] D. Spirkoska et al., Phys. Rev. B 80, 245325(2009)[3] I. Zardo et al., Phys. Rev. B 80, 245324 (2009)


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Organic Functionalization of Group IV-SemiconductorsM. Auernhammer, M. Hoeb, M. S. Brandt, J.A. Garrido, M. Stutzmann and I.D. SharpWalter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany

The covalent bonding of organic molecules to semiconductor materials allows the design of hybrid systems suitable for biosensor and (bio)molecular electronic applications. Silicon

carbide and diamond are promising substrate materials for such devices since they offer a unique combination of a number of desirable bulk and interfacial properties, including optical transparency, biocompatibility, and chemical stability.

In this work, we demonstrate a technique for thermally activated formation of alkene-derived self-assembled monolayers on oxygen-terminated surfaces by reaction with 1-octadecene (C18H36). In 1993 Linford et al. introduced a wet-chemical process, commonly known as hydros-ilylation, which yields organic thin fi lms on silicon surfaces [1]. During this chemical reaction, the alkenes spontaneously self-assemble on H-terminated silicon surfaces and form covalent silicon-carbon bonds. The alkyl-monolayers show exceptional oxidation resistance in ambient air and electrically passivate the surface via the reduction of surface states. Here, a similar process is studied on SiC and diamond surfaces, which are primarily oxygen- or hydroxyl-ter-minated following HF or plasma treatment, respectively [2,3]. The reaction of alkenes with OH-terminated surfaces yields dense and chemically stable organic monolayers. The layers were characterized using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), Thermal desorption spectroscopy (TDS) and water contact angle measurements. This investigation reveals that alkenes selectively attach to the oxygen-terminated sites via a covalent oxygen bridges. This work thus increases the range of available functionalization protocols and provides a new means of straightforwardly form-ing self-assembled organic monolayers on semiconductors in order to engineer their surface properties.[1] M.R. Linford, P. Fenter, P.M. Eisenberger, C.E.D. Chidsey, Journal of the American Chemical Society 117 (1995) 3145.[2] U. Starke, Ch. Bram, P.R. Steiner, W. Hartner, L. Hammer, K. Heinz, K. Müller, Applied Surface Science 89 (1995) 175.[3] H. Notsu, I. Yagi, T. Tatsuma, D.A. Tryk, A. Fujishima, J. Electroanal. Chem. 492 (2000) 31.

Fig. 1: Schematic representation of the alkyl self-assembly via functionalization of diamond-and silicon carbide surfaces.


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Organized growth of bifunctional oligoarenes and organometallic complex linkers on semiconductor nanoscale devicesCattani-Scholz1, K-C. Liao2, A. Bora3, A. Pathak3, I.D. Sharp1, C. Hundschell4, B. Nickel4, J. Schwartz2, M. Tornow3, G. Abstreiter1

1 Walter Schottky Institut, Physik Department, Technische Universität München, Germany 2 Department of Chemistry, Princeton University, NJ, USA3 Institut für Halbleitertechnik, TU Braunschweig, Germany4 Department of Physics, Ludwig Maximillian Universität München

We report on the successful deposition of self-assembled monolayers (SAMs) of sexithio-phene- and anthracene bisphosphonates onto silicon dioxide/silicon substrates. These

SAMs further served as a basis for the preparation of novel three-dimensional, organized bilay-ers of sexithiophene- and anthracene bisphophonates, using techniques of coordination che-mistry under controlled conditions by deposition of organometallic linkers onto the monolayers. We have characterized the mono- and bilayer systems on planar surfaces by XPS, AFM and XRR measurements. Our preliminary results indicate a high structural quality regarding layer composition, thickness and density.

Further, we discuss fi rst electrical characterization data of our aromatic organophosphonate systems, both in vertical transport using a metal top electrode, and laterally in-between nano-gap electrodes.


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Optoelectronic properties of two-dimensional gold nanoparticle arraysB. Dirks, C. Weiß, M.A. Mangold, A.W. HolleitnerWalter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

The fi eld of plasmonics deals with the interaction of light with metal clusters. It has drawn a lot of interest in recent years due to possible applications for surface enhanced Raman

spectroscopy and biosensing. The absorption of light by nanoparticles induces surface plasma oscillations of the conduction electrons. At fi rst, this leads to a strongly enhanced electrical fi eld at the surface of the particles and, secondary, the plasmons decay and heat up the particles. We use self-assembled two dimensional arrays of alkane coated gold nanoparticles to investi-gate the impact of these two effects on the transport properties of such arrays.

By probing the photoconductance of a contacted gold nanoparticle array we fi nd a clear en-hancement of the photoconductance at the surface plasmon resonance. This can be explained by bolometrically enhanced tunnel rates between adjacent nanoparticles [1]. Furthermore, fi -nite difference time domain simulations have shown a strong fi eld enhancement between the nanoparticles in the array under optical excitation of the surface plasmons. This fi eld enhance-ment leads to a strongly increased optoelectronic response of the nanoparticle array [2].

We acknowledge a fruitful collaboration with M. Calame and C. Schönenberger. This work has been supported by the “Deutsche Forschungsgemeinschaft” through project HO 3324/2, the excellence program “Nano Initiative Munich” (NIM), and the Center for NanoScience (CeNS) in Munich.[1] Mangold, M.A.; Weiss, C.; Calame M.; Holleitner A.W.: Appl. Physics Letters 94, 161104 (2009).[2] Mangold, M.A.; Weiss, C.; Dirks, B.; Holleitner A.W.: arXiv: 1004.5353 (2010).


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Spin waves in individual and periodic permalloy nanostructuresG. Duerr, K. Thurner, F. Brandl, S. Neusser, R. Huber, T. Schwarze and D. GrundlerLehrstuhl für Physik funktionaler Schichtsysteme, Technische Universität München, Physik-Department, James-Franck-Strasse, 85748 Garching b. Muenchen, Germany

The research fi eld of magnonics addresses the generation, manipulation and detection of spin waves (SWs) on the nanoscale [1]. For SW wave guiding individual as well as inter-

connected ferromagnetic nanowires have been found to be promising [2]. Characteristic lat-eral feature sizes of such devices range from a few 10 nm up to several 100 nm. Periodically patterned ferromagnets are also of particular interest as they can form artifi cial crystals and provide ultimate control of the fl ow of spin waves [3]. We present three recent advances in our study of structured and unstructured ferromagnetic thin fi lms.

Magnonic devices are prepared from 25 nm thick permalloy (Ni80Fe20) fi lms. To explore in detail the spin wave propagation properties and damping characteristics prior to nanopatterning we use all-electrical spin wave spectroscopy (AESWS) [4] and vary the temperature from 4 K up to 400 K. Applying out-of-plane fi elds of up to 2.5 T we study the intrinsic damping parameter of the permalloy thin fi lms used for the magnonic nanodevices.

To form SW wave guides we prepare 300 nm wide nanowires using electron beam lithography and lift-off processing of polycrystalline permalloy. Using an in-plane magnetic fi eld H applied in different spatial directions we vary the domain confi guration and local magnetization in the nanowires. This gives rise to different spin wave modes. We focus on the magnetic zig-zag confi guration which has been reported earlier to provoke deep-submicron SW channels [5]. Using AESWS we determine the resonance frequencies of these modes and study the propa-gation behavior.

Antidot lattices, i.e., periodic arrays of holes in a ferromagnetic thin fi lm such as permalloy, rep-resent interconnected networks of nanochannels and might provoke artifi cial crystal behavior [1,2]. We have studied holes with a diameter of 120 nm arranged on squared periodic lattices with different lattice constants. The arrays have been etched using focused ion beam lithogra-phy. By means of AESWS propagation of spin waves has been studied depending on the in-plane fi eld H [4]. Propagation velocities and intensities are found to vary signifi cantly depending on the strength and orientation of H [4,6]. Such characteristics are interesting for tunable wave guiding and applications in the framework of the emerging research fi eld of magnonics.

We thank A. Holleitner, T. Rapp, J. Topp, and P. Weiser for experimental support. The research leading to these results has received funding from the European Community’s Seventh Frame-work Programme (FP7/2007-2013) under Grant Agreement n° 228673 MAGNONICS and the German excellence cluster “Nanosystems Initiative Munich (NIM)”.[1] V.V. Kruglyak, S.O. Demokritov, and D. Grundler, J. Phys. D: Applied Physics 43, 264001 (2010).[2] S. Neusser and Dirk Grundler, Advanced Materials 21, 2927 (2009).[3] J. Topp, D. Heitmann, M. Kostylev, and D. Grundler, Phys. Rev. Lett. 104, 207205 (2010).[4] S. Neusser, G. Duerr, H.G. Bauer, S. Tacchi, M. Madami, G. Woltersdorf, G. Gubbiotti, C.H. Back,

and D. Grundler, Phys. Rev. Lett. 105, 067208 (2010).[5] J. Topp, J. Podbielski, D. Heitmann, and D. Grundler, Phys. Rev. B 78, 024431 (2008).[6] S. Neusser, G. Duerr, S. Tacchi, M. Madami, G. Gubbiotti, and D. Grundler, in preparation.


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Graphene solution-gated fi eld effect transistor arrays for sensing applicationsL. Hess1, M. Dankerl1, M. Hauf1, A. Lippert1, S. Birner1, I.D. Sharp1, M. Stutzmann1, J.A. Garrido1

1 Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

Biosensing and bioelectronic applications have enormously profi ted from employing fi eld effect transistors as transducing devices, mainly due to their intrinsic amplifi cation capa-

bility and the high integration offered by semiconductor technology. Due to the maturity of Si technology, most of the work with the so-called solution-gated fi eld effect transistors (SGFETs) has been done based on Si-MOSFETs. However, several disadvantages of the Si technology, such as high electronic noise and poor stability, have motivated the search for more suitable materials. The sensitivity of SGFETs devices largely depends on the distance between the con-ductive channel and the surface. Therefore, the use of FETs structures with surface channels offer clear advantages. In this respect, the surface conduction of graphene appears as an ideal candidate for the development of highly sensitive SGFETs.

A few recent studies have shown that the conductivity of graphene fi lms can be modulated using an electrolyte gate1,2. Here, we demonstrate a facile route for the scalable fabrication of transistor arrays that operate in aqueous environments using epitaxial graphene on SiC3 and CVD-grown graphene on SiO2. Furthermore, we utilize an on-chip structure for Hall ef-fect measurements which allows direct determination of carrier concentrations and mobilities under electrolyte gate control. The study of the graphene/electrolyte interface reveals a high interfacial capacitance (few μF/cm2), resulting in a high transconductance and correspond-ingly high sensitivity of the SGFETs. Through direct measurement, together with application of a model which considers the microscopic structure of water at the interface, we analyze the effect of gate potential on both hole and electron transport. Finally, the low-frequency noise of graphene SGFETs operating in electrolyte is investigated, revealing an effective gate noise of tens of μV, which compares very well with low-noise Si devices currently used in bioelectronic applications. Our study3 demonstrates that graphene SGFETs, with their facile technology, high transconductance, and low noise promise to far outperform state-of-the-art Si-based devices for biosensor and bioelectronic applications.[1] P.K. Ang, W. Chen, A.T.S. Wee, and K.P. Loh, J. Am. Chem. Soc. 130, 14392 (2008)[2] Y. Ohno, K. Maehashi, Y. Yamashiro, and K. Matsumoto, Nano Lett. 9, 3318 (2009)[3] M. Dankerl, V.M. Hauf, A. Lippert, L. Hess, S. Birner, I.D. Sharp, A. Mahmood, P. Mallet, J.Y. Veuillen, M. Stutzmann, and J.A. Garrido, Adv.

Funct. Mater., accepted (2010)


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AlGaN/GaN semiconductor biosensors for applications in radiation biophysicsM. Hofstetter1, J. Howgate2, I. D. Sharp2, M. Stutzmann2 and S. Thalhammer1

1 Helmholtz Zentrum München, Institute for Radiation Protection, Ingolstädter Landstraße 1, D-85764 Neuherberg, Germany2 Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

In recent decades, signifi cant efforts have been devoted to the development of biosensors that are capable of measuring changes and responses at a cellular level. Semiconductor sensors

based on gallium nitride and its alloys are particularly promising and devices capable of bio-sensing on a cellular and tissue level have been already demonstrated [1]. Here, we present a new concept in radiation biophysics for in situ monitoring of alterations in the microenvironment of cellular systems. We record the sensor response to X-ray irradiation in real-time with charge and pH sensitive solution gate AlGaN/GaN high electron mobility transistors (HEMTs). At the interface of the two materials, the difference in polarizations leads to a fi xed space charge and a two-dimensional electron gas (2DEG) is produced. The electrical properties, and there-fore the conductivity, of the system strongly depend on the surface potential of the chip. We demonstrate that the devices are stable and show reproducible behaviour under constant and pulsed X-ray radiation [2]. The HEMT devices are biocompatible and can be simultaneously operated in aggressive fl uids and under hard radiation. We have performed tests regarding cell proliferation and growth dynamics on GaN sensor surfaces to ensure biocompatibility as well as biofunctionality. Titration measurements in solution reveal that the linear pH response and sensitivity are retained under X-ray irradiation and devices can be simultaneously operated as radiation dosimeters. [1] G. Steinhoff et al., Appl. Phys. Lett. 86 (2005) 033901[2] M. Hofstetter et al., Appl. Phys. Lett. 96 (2010) 092110


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Spin wave resonances in ferromagnetic thin fi lms prepared via atomic layer depositionR. Huber1, P. Berberich1, T. Rapp1, J. Bachmann2, K. Nielsch2, and D. Grundler1

1 Lehrstuhl für Physik funktionaler Schichtsysteme, Physik Department E10, Technische Universität München, James-Franck-Str., D-85748 Garching b. München, Germany

2 Institut für Angewandte Physik und Mikrostrukturzentrum, Universität Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany

On the way to artifi cially designed three-dimensional magnetic structures atomic layer de-position (ALD) is a promising thin-fi lm deposition technique. We have produced different

ferromagnetic thin fi lms by an ALD from the company PicoSun. The fabrication is based on the oxidation of FeCp2 (NiCp2). [1,2] Afterwards iron oxide (nickel oxide) is reduced inside the ALD reactor by H2 at 400°C. The multi-source ALD reactor allows us to provide a cap layer of Al2O3 which prevents the magnetic thin fi lm from oxidation. We have studied the quasistatic and dy-namic properties via the magneto-optical Kerr effect and broadband spin-wave spectroscopy, respectively. In the latter case we mount the thin fi lm on top of a coplanar waveguide with an inner conductor exhibiting a width of 20 μm. Using a vector network analyzer we measure spin wave resonances. They depend characteristically on an applied in-plane fi eld and follow the well-known Kittel formula. We will discuss the magnetic properties of different ferromagnetic thin fi lms such as Fe and Ni fabricated by ALD.

We thank Sebastian Neusser for experimental help in the initial stage of the experiment. We acknowledge fi nancial support through the European Community’s Seventh Framework Pro-gramme (FP7/2007-2013) under Grant Agreement no. 228673 MAGNONICS.[1] J. Bachmann et al., J. Appl. Phys., 2009, 105, 07B521[2] M. Daub et al., J. Appl. Phys., 2007, 101, 09J111


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A Bose-Einstein condensate coupled to a micromechanical oscillatorsD. Hunger1,2, S. Camerer1,2, T. W. Hänsch1,2, D. König1, J. P. Kotthaus1, J. Reichel3 and P. Treutlein1,2,4

1 Ludwig-Maximilians Universität, Munich, Germany2 Max-Planck Institute of Quantum Optics, Garching, Germany3 Laboratoire Kastler Brossel, E.N.S, Paris, France4 University of Basel, Basel, Switzerland

Ultracold atoms can be trapped and coherently manipulated close to a surface using chip-based magnetic microtraps on so-called atom chips. This opens the possibility of studying

interactions between atoms and on-chip solid-state systems such as micro- and nanostruc-tured mechanical oscillators. Such oscillators have attracted attention due to the extreme force sensitivity and the novel manipulation techniques of cavity optomechanics. The question is raised whether the toolbox for quantum manipulation of ultracold atoms could be employed to read out, cool, and coherently manipulate the oscillators’ state. Several theoretical proposals show that suffi ciently strong and coherent coupling between atoms and oscillators would en-able studies of entanglement, quantum state transfer, and quantum control of mechanical force sensors.

In our experiment we demonstrate a fi rst step in this direction and couple the vibrations of a micromechanical cantilever to the collective motion of Bose-condensed atoms in a trap. The interaction relies on surface forces experienced by the atoms at about 1μm distance from the cantilever. We observe resonant coupling to several well-resolved mechanical modes of the condensate, including in particular the center of mass mode and the breathing mode. We use trap loss as the simplest way to detect the atomic motion induced by the coupling. With this method we are able to sense cantilever oscillations with a minimum resolvable amplitude of 13 nm, limited by the atomic trap lifetime and trap anharmonicity.

Coupling via surface forces does not require magnets, electrodes, or mirrors on the oscillator and could thus be employed to couple atoms to molecular-scale oscillators such as carbon nanotubes.

D. Hunger et al., Phys. Rev. Lett. 104, 143002 (2010)


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Optomechanical coupling of ultracold atoms and a membraneMaria Korppi1,2,3, A. Jöckel1,2,3, D. Hunger1,2, S. Camerer1,2, M. Mader1,2, T.W. Hänsch1,2 and P. Treutlein1,2,3

1 Ludwig-Maximilians-Universität, München, Germany2 Max-Planck-Institut für Quantenoptik, Garching, Germany3 Universität Basel, Switzerland

We report the recent results of our experiment, where we couple a single mode of a high-Q membrane-oscillator to the motion of laser-cooled atoms in an optical lattice. The opti-

cal lattice is formed by retrorefl ection of a laserbeam from the oscillator surface. Quantum fl uctuations of the lattice laser light mediate coupling between the motion of the atoms and the membrane1. When the trap frequency of the atoms is matched to the eigenfrequency of the membrane, the coupling leads to resonant energy transfer between the two systems. We have observed such resonant energy transfer both from the membrane to the atoms and, more sig-nifi cantly, the back-action of the atoms on to the membrane.

In the long term, such coupling mechanism could be exploited in developing hybrid quantum systems between atoms and solid-state devices. As another intriguing perspective, a new gen-eration of optical lattice experiment is in sight, where the mirrors creating the laser standing waves are micromechanical oscillators which interact with the atoms, and, which ultimately must be described quantum mechanically. 1 Optical Lattices with Micromechanical Mirrors, K. Hammerer, K. Stannigel, C. Genes, P. Zoller, P. Treutlein, S. Camerer, D. Hunger, T.W.

Haensch, arXiv:1002.4646

Figure: Optical lattice mediates the coupling be-tween ultracold atoms and a membrane placed in separate vacuum chambers.


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Photoconductance of a submicron oxidized line in surface conductive single crystalline diamondM. Seifert, M. Stallhofer, M. V. Hauf, G. Abstreiter, M. Stutzmann, J. A. Garrido and A.W. Holleitner Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching

Undoped single crystalline hydrogen-terminated diamond exhibits a p-type surface conduc-tivity. This surface conductivity originates from a two-dimensional hole gas formed due

to a band bending beneath the surface [1]. An oxygen-terminated diamond surface, however, shows no surface conductivity and, therefore, thin oxidized lines can act as effi cient energy bar-riers within the two-dimensional hole gas [2]. We investigate the sub-bandgap optoelectronic phenomena induced by such a barrier in hydrogenated diamond at room temperature. The sub-micron oxidized lines are defi ned in single-crystalline diamond by electron beam lithography in combination with an oxygen plasma treatment. We observe a photoconductive gain of the hole conductivity across the barrier for sub-bandgap illumination [3]. The fi ndings are consistent with the infl uence of photogenerated electrons being trapped in defect levels within the oxidized lines. We discuss the spatial and energetic characteristics as well as typical timescales of the optoelectronic phenomena. Our fi ndings suggest that surface conductive diamond circuits can be tailored by submicron oxidized lines in order to build photodetectors in the ultraviolet range at room temperature.

We acknowledge fi nancial seed-funding by the German excellence initiative via the “Nanosys-tems Initiative Munich (NIM).”[1] F. Maier, M. Riedel, B. Mantel, J. Ristein, and L. Ley, Phys. Rev. Lett. 85, 3472 (2000).[2] J. A. Garrido, C. E. Nebel, R. Todt, G. Rösel, M.-C. Amann, and M. Stutzmann, Appl. Phys. Lett. 82, 988 (2003).[3] M. Stallhofer, M. Seifert, M. V. Hauf, G. Abstreiter, M. Stutzmann, J. A. Garrido, and A.W. Holleitner, Appl. Phys. Lett. 97, 111107 (2010).


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Polymer Brushes on GrapheneMarin SteenackersWACKER-Lehrstuhl für Makromolekulare Chemie, Technische Universität München, Lichtenbergstraße 4, 85747 Garching, Germany

Graphene has been attracting great interest because of its distinctive band structure and physical properties. Here, we report on the preparation of large-area and free-standing

fi lms of the order of centimeters consisting of a single graphene layer covalently modifi ed with a soft and fl exible functional polymer brush layer. These self-supporting nanomembranes, also referred to as “polymer carpets”, were prepared by a two-step procedure: fi rst, a high quality and uniform single graphene layer, prepared by chemical vapor deposition on copper foils, was functionalized with polymer brushes by direct photografting of styrene. In a second step, the copper foil was etched away in an aqueous (NH4)2S2O8 solution resulting in a fl oating graphene/polymer brush membrane which could easily be transferred to other substrates. The introduc-tion of complex chemical functionalities within the polymer carpet can be prepared directly by polymer analogue reactions of the polystyrene brushes. Polymer carpets, based on crosslinked monolayers, were found recently to exhibit remarkable and unprecedented properties combin-ing extreme thinness, mechanical and chemical stability, robustness, fl exibility and (chemical) sensitivity. Our results provide a new set of tools for covalent chemical functionalization and manipulation of single graphene layers for the development of new integrated micro-/nanotech-nological devices.


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Spatially resolved optoelectronic measurements of organic thin fi lm transistorsChristian Westermeier, Matthias Fiebig, and Bert NickelDepartment für Physik and CeNS, Ludwig-Maximilians-Universität, Geschwister-Scholl-Platz 1, 80539 München, Germany

Pentacene is a promising candidate for organic electronics and optoelectronic applications due to its high charge carrier mobility and strong absorption properties. Its optical proper-

ties are highly anisotropic. Therefore, the thin-fi lm-phase texture of pentacene grains should be visible in polarized light due to anisotropic absorption. Being the initialising step to generate excitons, absorption is crucial for the photoresponse of transistors. Consequently, the poly-crystalline thin-fi lm-phase texture might be directly related to the photoresponse of pentacene based OFETs.

Here, we use local illumination of the transistor channel in a confocal laser scanning setup with submicron resolution which allows us to excite single pentacene grains. Due to the random orientation of the single crystals on the substrate, the refl ection from different grains varies de-pending on the polarization direction of the incident light, as expected. The sharp luminescence image mirrors the thin-fi lm texture and thus absorption and luminescence measurements match up perfectly. However, the spatially resolved photoresponse of the pentacene OFET shows an extrinsic structure which is diffuse and almost independent of the polarization. To disentangle the different contributions of the underlying transport phenomena, we perform time resolved photoresponse measurements. Apart from a heat-induced homogeneous mechanism, these measurements also reveal two spatially inhomogeneous processes with different timescales. A structured and slow component is observed within the transistor channel, whereas a faster mechanism occurs close to the positive electrode. The obtained results for the photoresponse of pentacene based OFETs are explained by a model of triplet exciton assisted hole detrap-ping.


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Compact and Nanotubular TiO2 in Energy ResearchCeline Rüdiger1, Silvia Leonardi1,2, Florian Wiesinger1, Odysseas Paschos1, Fabio Di Fonzo2, Andrea Li Bassi2, Ulrich Stimming1 and Julia Kunze1

1 Institute for Advanced Study (IAS) and Department of Physics E19, Technische Universität, München, Germany2 Politecnico di Milano NEMAS - Center for Nano-Engineered Materials and Surfaces, Milano, Italy

Self-organized nanostructured oxides grown by optimized metal anodization have attracted remarkable interest in the past decades. Starting with the growth of nanoporous alumina

[1], this type of anodic oxide fi lms can nowadays be grown on various valve metals and their alloys using dilute fl uoride based electrolytes. Upon all valve metal oxides, nanotubular TiO2 on Ti [2,3] is among the most promising structures since it offers several interesting functional properties.

The growth of self-organized TiO2 nanotube arrays on electropolished and not electropolished Ti sheets was investigated for three different electrolytes, being fl uoride ion containing sulphate and phosphate buffer solutions as well as glycerol-based electrolytes. A systematic structural and morphological characterization was performed revealing an interdependence of the crys-tallographic orientation of the grains in polycrystalline Ti and the growth rates and properties of nanotubular TiO2 layers.

While the semiconductive nature of TiO2 is crucial for many applications for example in photo-catalysis, the limited conductivity prevents an effi cient use in applications that require a fast electron transport, functional electrodes or electrocatalyst supports. For the latter application TiO2 has to be made conductive and inert towards reoxidation in the electrolyte. This can be achieved by a carbo-thermal reduction treatment converting the TiO2 into an oxy-carbide com-pound (TiOxCy) that shows stable semimetallic conductivity [4].

A parameter study has been performed for compact TiO2 fi lms on Ti sheets to optimize the carbo-thermal reduction. The composition, morphology and structure of the fi lms before and after the conversion have been studied with XPS, SEM, AFM and XRD. The conductivity of the fi lms was electrochemically investigated with the well understood redox system Fe(CN)6

3-/4-.

With the aim to investigate the nanotubular and compact TiOxCy layers as support materials for electro catalytically active metals like Pt and Pd, a study of Pt-deposition on compact TiOxCy fi lms was performed. Further effort will be devoted to the investigation of the infl uence of the metal coverage, the particle thickness and shape, and the metal oxidation state on the catalytic activity for ORR and alcohol oxidation. The infl uence of the TiOxCy support will be studied by looking at different oxygen to carbon ratios.[1] H. Masuda, K. Fukuda, Science, 268 (1995) 1644.[2] V. Zwilling, M. Aucouturier, E. Darque-Ceretti, Electrochim. Acta 45 (1999) 921.[3] J.M. Macak, H. Tsuchiya, A. Ghicov, K. Yasuda, R. Hahn, S. Bauer, P. Schmuki, COSSMS (2007).[4] R. Hahn, F. Schmidt-Stein, J. Salonen, S. Thiemann, Y.Y. Song, J. Kunze, V.-L. Lehto, P. Schmuki,

Angewandte Chemie Int. Ed. (VIP Paper) 48 (2009) 7236.


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Investigation of the thermal conductivity of GaAs nanowires by Raman spectroscopy combined with laser heatingMartin Soini1, Ilaria Zardo1, Emanuele Uccelli1,2, Stefan Funk1, Gregor Koblmüller1, Anna Fontcuberta i Morral1,2, and Gerhard Abstreiter1

1 Walter Schottky Institut, Technische Universität München, Garching, Germany2 Laboratoire des Matériaux Semiconducteurs, Institut des Matériaux, Ecole Polytechnique Fédérale de Lausanne,

CH-1015 Lausanne, Switzerland

In order to make thermoelectrics a competitive technology, materials with high electric and low thermal conductivity are required. Recently, this has increased the interest in nanoscale

systems for thermoelectric application. Nanowires are promising candidates for the reduction of the thermal conductivity due to increased boundary scattering, while keeping the electrical conductivity high [1,2].

We investigated the thermal conductivity κ of GaAs NWs. Our method is based on the laser heating of freely suspended NWs and the determination of the local temperature by μ-Raman spectroscopy.

The thermal profi le measured for homogeneous nanowires shows parabolic behavior, which is in agreement with the simple model proposed by Hsu et al. [3]. The fi t to the temperature profi le is used to extract κ. The absolute value of the laser power absorbed inside the nanowire, which is needed for the determination of κ, is determined by fi nite differences simulations. The con-ductivity is found to be in the range of 10 to 35 Wm-1K-1 and therefore to be signifi cantly lower than in bulk GaAs. Furthermore, our results confi rm recent theoretical calculations by Martin et al. [4].

The exposition to laser light with high power induces the oxidation of the GaAs, affecting the properties of the nanowires in an irreversible manner. We determined a systematic increase of the thermal resistance with increasing laser power.

The reliability of the determination of the local temperature on a micrometer scale by Raman spectroscopy is demonstrated by applying this method to nanowires with morphological inho-mogeneities. Furthermore, the measurement on tapered nanowires proofs the decrease of the thermal conductivity for smaller diameters.

Upper left: Typical sample confi guration: The nanowire is freely suspended between two gold pads. Scale bar: 1 μm. Lower left: Spacially resolved Raman measurement on a single nano-wire. The shift of the TO peaks is used to calculate the local temperature. Right: Parabolic temperature profi le measured on a homogeneous nanowire. The solid lines are the fi t curves to the experimental points. [1] A. I. Hochbaum, R. Chen, R. D. Delgado, W. Liang, E. C. Garnett et al., Nature 451, 163 (2008)[2] G. J. Snyder, and E. S. Toberer, Nature Materials 7, 105 (2008)[3] I-K. Hsu, R. Kumar, A. Bushmaker, S. B. Cronin, M. T. Pettes et al., Appl. Phys. Lett. 92, 063119 (2008)[4] P. N. Martin, Z. Aksamija, E. Pop, and U. Ravaioli, Nano Lett. 10, 1120 (2010)


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Investigation of different interface morphologies in organic solar cellsWolfgang Wiedemann1, Alaa Abdellah2, Holger Hesse1, Jonas Weickert1, Robert Meier3, Kevin P. Musselman4, Judith L. MacManus-Driscoll4, Peter Müller-Buschbaum3, Giuseppe Scarpa2, Paolo Lugli2, and Lukas Schmidt-Mende1

1 Dept. of Physics & Center for NanoScience (CeNS), Ludwig-Maximilians University, Munich, Bavaria, Germany.2 Institute for Nanoelectronics, Technical University Munich, Munich, Bavaria, Germany.3 Physik-Department LS E13, Technical University Munich, Munich, Bavaria, Germany.4 Dept. of Materials Science and Metallurgy, University of Cambridge, Cambridge, United Kingdom.

The morphology in organic photovoltaics plays a key role in determining the device effi cien-cy. We present polymer solar cells with different interfacial geometry and their fabrication

processes to investigate the exact role of this morphology. We compare different device archi-tectures: bilayer, blend, stratifi ed and nanostructured bilayer solar cells. The bilayer solar cell is fabricated by a transfer technique, where [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) is laminated on top of a poly(3-hexylthiophene) (P3HT) fi lm. The blend device is spincoated from a mixed solution of both materials and shows a homogeneous intermixing of the donor and ac-ceptor material. The stratifi ed solar cell has a continuous transition between each active mate-rial and can be obtained by spincoating a PCBM layer from an orthogonal solvent for P3HT on top of the P3HT fi lm. The nanostructured device is a bilayer architecture with controlled nano-structured interfaces by combining nanoimprinting and lamination techniques: before laminat-ing the second organic layer, the fi rst is imprinted by an anodic aluminum oxide (AAO) stamp. This technique allows us to achieve a network structure of donor-acceptor material with a ~80 nm periodicity and ~40 nm width. These structures have an abrupt interface between the donor and acceptor materials and show an increased effective interfacial area and photovoltaic performance compared to bilayers. In contrast to blend fi lms, they allow an in depth analysis of the infl uence of morphology on interfacial physical processes.

To get an insight into the recombination- and dissociation process and also the carrier transport, we apply transient measurements, such as photovoltage decay (PVD). Photoluminescence (PL), temperature- and light intensity dependent I-V measurements provide additional informa-tion about the device physics. Gracing small and wide angle X-ray scattering data are shown to reveal imformation about the interfacial morphology and the polymerchan orientation. The studies of the different device architectures provide insights to the ideal device morphology.


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Regulation of Cellular Signaling Pathways by Spatial Organization of Molecular Extracellular Matrix CuesYvonne Schön1, Vera C. Hirschfeld-Warneken1, Heike Böhm1, Stefanie Neubauer2, Horst Kessler2, and Joachim P. Spatz1

1 Max-Planck-Institut für Metallforschung, Stuttgart, Germany2 Institute for Advanced Study at the Department Chemie, Technische Universität München, Lichtenbergstr. 4, D-85747 Garching, Germany

Spatial patterning of biochemical cues on the micro- and nanometer scale controls numer-ous cellular processes such as spreading, adhesion, migration, and proliferation. Espe-

cially αvβ3 integrin mediated cell adhesion is crucially infl uenced by ligand design, spacing and global ligand density. With synthetic cell environments we are able to precisely control integrin activation by the presentation of the activating ligand: the gold nanoparticles employed as an-chorpoints can be positioned by a self-assembly technique assigning particle spacing and con-sequentially global particle density. Moreover, further developments of this method also allow the independent adjustment of local spacing and global density by a combination of micro- and nanostructuring approaches or the variation of the particle spacing in a gradient along the pat-terned glass slides.

In combination with ligands specifi cally designed to match the addressed integrins these ad-hesive nanostructured surfaces are a versatile tool to analyze cell attachment, spreading and migration. In combination with single cell force microscopy the adhesion strength of cells in dependence of their integrin activation and focal contact formation can be controlled and ana-lyzed at the subcellular level.


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Expanding the Scope of Single Molecule FRET with DNA OrigamiCarlos Castro, Hendrik DietzDietz Lab, Physik Department, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

Typical dimensions of cellular components are on the order of a few nanometers and their diverse cellular functions often involve conformational changes that require movements

ranging from fractions of a nanometer up to tens of nanometers. The current state of the art tool for studying conformational dynamics is single molecule Fluorescence Resonance Energy Transfer (FRET), whereby energy transfer between two fl uorescent dyes is correlated to their spatial separation; however, quantitative distance predictions require case-specifi c calibrations and are only accurate in the range of ~ 3-7 nm. Furthermore, the working range is limited to below 10 nm.

Here we present a nanoscale device constructed by DNA origami that improves the quantita-tive accuracy of FRET distance predictions and expands its potential working range. The de-vice integrates 3d structures built from self-assembled DNA, attachment sites for molecules of interest, sites for surface immobilization, and fl uorescent markers for the direct visualization of biomolecular dimensions and dynamics by FRET. The device takes advantage of a distance calibration that can be generally applied to any molecule of interest. We have demonstrated that the device can easily achieve 1 nm distance resolution. For the purpose of proof-of-concept studies we specifi cally integrated a piece of double stranded DNA (dsDNA) containing a recognition sequence for Catabolite Activator Protein (CAP), which is know to bend dsDNA upon binding, between the arms of this device. The bending angle will be evaluated with single particle electron microscopy (EM), and FRET microscopy will be employed in solution to re-solve real-time kinetics and deformations of CAP-DNA binding.


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Sensing applications of GaN-based devicesJohn D. Howgate1, Markus Hofstetter2, Sebastian Schoell1, Stefan Thalhammer2, Ian D. Sharp1 and Martin Stutzmann1

1 Walter Schottky Institut, Technische Universität München, Am Coulombwall 3, 85748 Garching, Germany2 Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany

Our research is dedicated to the investigation of interfaces between wide bandgap semicon-ductors and organic systems for biosensing and bioelectronic applications. For this pur-

pose, the fundamental operation of electrolyte-gated high electron mobility transistors (HEMTs) based on AlGaN/GaN heterostructures is studied in terms of ionic interactions at the surface, pH sensitivity, and charge transfer processes. A particular emphasis of this work is the devel-opment of top-down techniques for miniaturization of the HEMT channel in order to enhance sensitivity, with an end goal of reaching nanoscale devices. In addition, we have investigated the catalytic activity of covalently bound enzymes on the transistor gates by immobilization of penicillinase for detection of the catalytic product penicillic acid from penicillin. Possibilities for direct charge transfer between GaN and grafted biomolecules have also been explored. We have found that the energetic alignment at these hybrid interfaces allows photo-catalytic cleav-age of self-assembled monolayers via UV-induced charge transfer from GaN substrates and have demonstrated that GaN and SiC are promising materials to accommodate direct charge transfer from photosynthetic reaction centers. The high sensitivity of electrolyte-gated AlGaN/GaN devices is further exploited for real time measurement of ionizing radiation doses and the responses of locally irradiated cells on the surfaces of devices.


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Organic Thin-Film Transistors for Applications in Radiation BiophysicsA.-L. Idzko1, G. Scarpa2, and S. Thalhammer1

1 Helmholtz Centre Munich, German Research Centre for Environmental Health, Ingolstädter Landstraße 1, D-81377 Neuherberg, Germany

2 Technical University Munich, Institute for Nanoelectronics, Arcisstrasse 21, D-81377 München, Germany

Here we present a biosensor setup based on organic semiconducting material for applica-tions in radiation biophysics. Organic polymers are extremely sensible on physical as well

as (electro-) chemical infl uences so they can be used to detect small pH-value changes and variations in ion concentrations. Both molecular structure and morphology are adjustable to fi ne-tune the chemical and physical properties, thus enhancing sensitivity and selectivity. The layout of the polymeric fi eld effect transistor device consists of a silicon substrate also acting as the gate of the transistor coated with silicon dioxide. On this dielectric an interdigitated pattern of electrodes is sputtered, acting as source and drain. The surface of the transistor is coated with the polymer P3HT with spin coating. P3HT is one of the most commonly used polymers as a conducting agent because it forms highly ordered thin fi lms and has the highest reported fi eld-effect mobility in polymer fi eld effect transistors so far, 3*10-3 cm2V-1s-1.

To overcome biocompatibility problems protein-based coatings and oxygen-plasma treatments were performed to enable growth of adherent living cells on those modifi ed surfaces. This new approach based on the interplay between organic and biological materials is motivated by the possibility of observing new phenomena or obtaining more detailed information from biologi-cally active systems for example cell-cell communication during and after irradiation.[1] G. Scarpa et al., Organic Electronics 10 (4) (2009) 573-580 [2] S. Thalhammer et al., Macremolecular Bioscience 10 (4) (2010) 378-383


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DNA Origami as a Molecular Platform for BionanotechnologyR. Jungmann1,3, C. Steinhauer2,3, M. Scheible1, A. Kuzyk1, P. Tinnefeld2,3, F.C. Simmel1,3

1 Lehrstuhl für Bioelektronik, Physik-Department, Technische Universität München, James-Franck-Straße 1, 85748 Garching, Germany 2 Angewandte Physik - Biophysik, Ludwig-Maximilians-Universität, Amalienstraße 54, 80799 München, Germany3 Center for NanoScience, Ludwig-Maximilians-Universität, Schellingstraße 4, 80799 München, Germany

DNA is now widely used as a programmable material for the construction of two- and three-dimensional nanostructures. Application of hierarchical assembly strategies as well as in-

tramolecular folding as in “DNA origami” has resulted in structures with low assembly error densities [1]. We currently explore the use of DNA origami in the context of biophysics and bionanotechnology. We use rectangular DNA origami labeled with fl uorophores at specifi c po-sitions as a nanoscopic ruler. Super-resolution fl uorescence microscopy based on the subse-quent localization of single molecules enables two fl uorophores at a distance of about 90 nm to be optically resolved. This combination of subdiffraction imaging and DNA nanotechnology opens up new avenues for studying nanostructures and their dynamics [2]. We have also de-veloped an assay for the investigation of kinetic and dynamic processes on DNA-based nano-structures using transient binding of short fl uorescently labeled imaging strands. The assay allows to routinely perform analysis of binding and dissociation kinetics on the single molecule level. The method, that we term DNA-PAINT, is used to investigate positional effects of DNA hybridization kinetics on DNA scaffolds as well as for super-resolution fl uorescence imaging of DNA nanostructure with a resolution < 30 nm.[1] Rothemund, P.W.K., Folding DNA to create nanoscale shapes and patterns. Nature, 2006. 440(7082): p. 297-302.[2] Steinhauer, C., et al., DNA Origami as a Nanoscopic Ruler for Super-Resolution Microscopy.

Angewandte Chemie-International Edition, 2009. 48: p. 8870-8873.


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Towards studying equilibrium unbinding/binding transitions of single protein complexes under force – enabled by DNA OrigamiFabian Kilchherr, Hendrik DietzLaboratory for Biomolecular Nanotechnology, Physik Department, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

Identifying and characterizing ubiquitously found adhesive interactions between biological macromolecules is key for understanding regulatory processes in biology. Single-molecule

force spectroscopy approaches can provide detailed mechanistic insight into the physical de-tails of intramolecular interactions inside protein structures. In this project we seek to enable the single-molecule study of intermolecular protein-protein and protein-nucleic acid interactions with dual-beam optical traps which has so far remained experimentally challenging. The con-ceived DNA Origami handles enable force spectroscopical measurements of receptor-ligand interactions. In addition, the presented handles are stiffer than usually used DNA double heli-ces. This leads to less noise in the force signal and an improved spatial and temporal resolu-tion.


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Fabrication and Electrical Characterization of a Pore-Cavity-Pore DeviceMartin Langecker, Daniel Pedone, Alexandra Mara Münzer, Ruoshan Wei, Robin Daniel Nagel and Ulrich RantWalter Schottky Institut, Technische Universität München, Germany

Single engineered nanopores in solid state membranes have attracted broad attention in recent years as a tool to study single biological molecules like DNA or proteins. Here we

present a novel concept for a nanopore structure in a silicon chip which does not only consist of a single nanopore in a membrane but comprises two stacked nanopores which form the op-posing in- and out-lets to a cavity with a volume of 10 femto liter.

The ‘pore-cavity-pore’ (PCP) device is fabricated by structuring nanopores into a sandwich SiN/Si/SiN wafer using e-beam lithography, wet chemical etching, and feedback controlled electrochemical etching steps. The in- and outlet nanopores are characterized by transmis-sion electron microscopy, evidencing that the pore diameters may be controlled independently down to 10 nm.

The electrical properties of the PCP structure are investigated by impedance spectroscopy under conditions which are typical for single molecule experiments, that is, when applying potentials across the device in electrolyte solution. Furthermore, we present a fi nite-element simulation of the electric fi eld inside the device.

The PCP device can be used to investigate single molecules both optically and electrically. We present a measurement chamber design that is capable of simultaneous electro-optical mea-surements.


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DNA origami supports for the analysis of complex samples by singe-particle electron microscopyThomas G. Martin and Hendrik DietzLaboratory for Biomolecular Nanotechnology, Physik Department, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

We introduce a new approach for imaging molecules with low contrast in an electron micro-scope. DNA origami structures are well defi ned structures with a high contrast in transmis-

sion electron microscopy. By binding an unknown object to DNA origami supports it is possible to determine its position even if the object’s contrast is lower than the gaussian background noise. Placing markers on the support provides additional information about the orientation which can be used to simplify 3D reconstruction.


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A Thermal Trap for DNA ReplicationChristof B. Mast and Dieter BraunSystems Biophysics, Ludwig-Maximilians-Universität München, Fakultät für Physik, Amalienstr. 54, D-80799 München, Germany

Normally, genetic information is protected from free diffusion into the environment by cell walls. The cells provide all conditions for the replication and mutation of genetic material

- the basic prerequisite for Darwinian evolution. We modeled a fundamental principle in the laboratory, which allows for continuous evolution of genetic material without cell membranes. We fi lled a thin capillary with DNA and nucleotides, solved in buffer as an aqueous solution (Figure c). A moving infrared laser spot then generated a thermal gradient realizing thermopho-resis as well as a cyclic convection of the solution. The superposition of both effects caused the double-stranded DNA molecules to migrate to the cold area (Figure a), while simultane-ously cycling the DNA between the cold and warm section of the capillary. In the hot area, the DNA separates into single strands. These are then elongated by a polymerase enzyme in the cold region to two double-stranded copies of the original template DNA (Figure b). Therefore, a simple temperature gradient drives both, an exponential replication as well as the selective ac-cumulation of information. This is relevant as presumably similar thermal conditions prevailed in rock pores near hot undersea springs of prehistoric oceans. Our experiment shows how a simple disequilibrium setting may allow life to evolve.


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Biochemistry on a leashMatthias Schickinger et al.Laboratory for Biomolecular Nanotechnology, Physik Department, Technische Universität München, Am Coulombwall 4, D-85748 Garching, Germany

Inter-macromolecular interactions play a major role in many biological processes. In order to better understand these processes it is essential to identify and quantify these protein-protein

and protein-nucleic acid interactions. The insights gained may be invaluable to many applica-tions in the fi elds of biotechnology or biomedicine, e.g. for targeted drugdesign. Here, we intend to introduce a new approach to single molecule measurements on receptor-ligand systems that, using a comparatively simple experimental setup, makes it possible to gain deeper insight into the kinetics of these systems. At the heart of this technique is a DNA origami structure consisting of two 18-helix blocks and a connecting single- or double-stranded DNA leash. The blocks attach to the respective receptor and ligand, respectively. One of the blocks is fi xed to a surface, the other one is free to move (but kept on the leash) and carries fl uorescent labels. By monitoring the magnitude of the mobile block’s movement in a fl uorescence microscope, we discriminate the bound state from the unbound state and measure directly the binding and un-binding times of our sample system. Once this method has been established, it can serve as a platform for the study of all kinds of inter-biomacromolecular interactions. Owing to its relatively basic instrumental requirements, it should be fairly easily reproducible. Furthermore, it would deliver a means to measure binding kinetics as a function of environmental conditions, under the infl uence of additional ligands and in a high-throughput and highly parallel fashion.


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Synthetic Assembly of Non-Peptidic Ligands for Constructing αvß3- and α5β1-Integrin based Focal AdhesionsA. Schwede1, S. Neubauer2, F. Rechenmacher2, H. Kessler2, J. Polleux1,3, H. B. Schiller3, R. Fässler3 and J. P. Spatz1 1 Department of New Materials and Biosystems, Max-Planck-Institute for Metals Research, Heisenbergstr. 3, 70569 Stuttgart, Germany2 Institute for Advanced Study (IAS), Department Chemie, Technische Universität München, Lichtenbergstr. 4, 85747 Garching, Germany3 Department of Molecular Medicine, Max-Planck-Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany

The ability of eucaryotic cells to react to their proximate environment, the so-called extracel-lular matrix (ECM), is a crucial biological phenomenon. It has been extensively described

in literature how cells effectively react in a coordinated, specifi c, localized manner to stimuli coming from their external environment. Depending on the defi ned chemical and physical char-acteristics of the underlying ECM, cell behaviour such as proliferation, differentiation, motility or even apoptosis can be greatly infl uenced.

New technologies and scientifi c approaches give us the thrilling opportunity of gaining innova-tive, clarifying insights into how cells sense their environment locally and yet react globally dis-playing a myriad of customized mechanical and biochemical responses. Our system is based on the self-organization of nanoparticles with a spatial control at the nanometer scale, which in turn serve as anchor points to signaling molecules of our choice. More specifi cally we work with gold nano-particles (AuNPs) covalently bound to a biologically inert apolar poly-ethylene-glycol (PEG) scaffold in a defi ned pattern with tuneable spacing. Using ligands covalently bound to these AuNPs that address specifi c signalling pathways offers us the unique possibility to better understand the relevance of these pathways in the formation/maturation/disassembly of fo-cal adhesions (FA). Therefore, these nano-structures offer highest spatial resolution regarding the positioning of single transmembrane receptors activation such as integrin activation and therefore FA formation and enable the testing of cellular response to individual specifi c signal molecules and their spatial patterning.

The challenge in this study is to direct FA formation by using different non-peptidic binding ligands at the same substrate on both the micro-scale and the nano-scale. With this technol-ogy we aim to construct synthetically FAs in living cells. Many questions arise: is it possible to form adhesion complexes consisting of two types of transmembrane receptors? How is signal transduction affected and how is the phenomenological reaction of cells to this directed ma-nipulation?


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Single Molecules as Energy, Force, Friction and Structure SensorsF. Stetter, T. Pirzer, B. Balzer, M. Geisler und T. HugelPhysik-Department E22, Technische Universität München, James-Franck-Str. 1, D-85748 Garching, Germany

During the last years we developed molecular sensors consisting of single polypeptides and an AFM tip. They allowed us to determine the interaction between single polymers

and solid substrates in aqueous environments. In particular we were able to understand how hydrophobic and dispersion forces determine polymer adhesion [1, 2].

Using these probes and single molecule force spectroscopy we study various phenomena and interfaces. In particular we will present how surface properties affect the adhesion force of polymers [3], how friction and adhesion are related on the nano level and how lipid bilayers determine the structure of amyloids like Alpha-Synuclein, a key peptide related to Parkinson’s disease.1. Horinek, D., et al., Peptide adsorption on a hydrophobic surface results from an interplay ofsolvation, surface, and intrapeptide forces. Proc Natl Acad Sci U S A, 2008. 105(8): p. 2842-7.2. Geisler, M., B.N. Balzer, and T. Hugel, Polymer adhesion at the solid-liquid interface probed bya single-molecule force sensor. Small, 2009. 5(24): p. 2864-9.3. Pirzer, T., et al., Single molecule force measurements delineate salt, pH and surface effects onbiopolymer adhesion. Phys Biol, 2009. 6(2): p. 025004.


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Single-Molecule Cut and Paste for Functional AssemblyMathias Strackharn1,2, Stefan. W. Stahl, Stefan K. Kufer, Elias M. Puchner, Hermann Gumpp, Stephan Heucke and Hermann E. Gaub1

1 Center for Nanoscience & Physics Department, University Munich, Amalienstr. 54, 80799 Munich, Germany2 [email protected]

Single-molecule cut-and-paste surface assembly (SMCP) [1] was employed for the con-trolled deposition of individual fl uorophores in well-defi ned nanometer sized patterns. We

combined a total internal refl ection fl uorescence microscope (TIRFM) with an atomic force mi-croscope (AFM) and used this ultrastable hybrid TIRF-AFM setup [4] to monitor the deposition process of single fl uorophores in real time and to determine their position with nanometer preci-sion. We were able to demonstrate the precision of the method and to point out the limitations [2]. SMCP allows for the creation of patterns of arbitrary shape and with arbitrary numbers of

single molecules consisting of multiple species. By making use of specifi c molecular interac-tion, like the coupling of streptavidin to biotinylated transfer DNA, we could provide with this technique a scaffold for the controlled self-assembly of nanoparticles [3]. We could further combine the technique with an elaborated superresolution microscopy technique and highlight which role reductants and oxidants play for aquisition speed and resolving power [5]. Recently we could build up from single molecular units a complex with a complete new function that oc-cured only due to the functional assembly. [1] Kufer, S. K., Puchner, E. M., Gumpp, H., Liedl, T. & Gaub, H. E., Single-Molecule Cut-and-Paste Surface Assembly, Science 319,

594-596 (2008) [2] Kufer S.K., Strackharn M, Stahl S.W., Gumpp H., Puchner E.M. & Gaub H.E., Optically monitoring the mechanical assembly of single

molecules, Nature Nanotechnology, Vol. 4, (2009) [3] Puchner, E. M., Kufer, S. K., Strackharn, M., Stahl, S. W. & Gaub, H. E., Nanoparticle Self-Assembly on a DNA-Scaffold written by

Single-Molecule Cut-and-Paste, Nano Letters, Vol. 8, No. 11 (2008) [4] Gumpp H., Stahl S.W., Strackharn M., Puchner E.M. and Gaub H.E., Ultrastable combined atomic force and total internal refl ection

fl uorescence microscope. - Review of Scientifi c Instruments, 80(6) (2009) [5] Cordes T., Strackharn M., Stahl S.W., Summerer W., Steinhauer C., Forthmann C., Puchner E.M., Vogelsang J., Gaub H.E., and

Tinnefeld P., Resolving Single-Molecule Assembled Patterns with Superresolution Blink-Microscopy, Nano Letters, Vol. 10 (2010)

Bio

-Nan

osc

ien

ce


Post

er P

rese

nta

tio

ns

Bio

-Nan

osc

ien

ce

Analysis of proteins on a chip with the switchSENSE platformRalf Strasser, Jens Niemax, Paul Hampel, Kenji Arinaga, and Ulrich RantWalter Schottky Institut, Technische Universität München, Am Coulombwall 3, D-85748 Garching, Germany

While established label-free surface biosensors are restricted to yield mere binding con-stants, the platform technology switchSENSE adds the unique capability of a size/shape

analysis during the same measurement run. By determining a protein’s hydrodynamic diameter with high accuracy, a wealth of previously inaccessible information can be revealed.

Short DNA molecules are chemically tethered to metal microelectrodes at one end. When applying AC voltages (0.1 Hz – 500 kHz) to the electrodes, the DNA molecules are repelled from -or attracted to- the surface. This molecular ‘switching’ is monitored in real time by optical means. Receptors attached to the DNAs’ upper ends serve as capture sites for target mol-ecules. Label-free targets which bind to the interface alter the switching behavior, and ‘classi-cal’ binding parameters (KD, kon, koff) can be obtained. Unprecedented for a biochip detection platform, additional information about the target molecule size and shape is inferred from a molecular dynamics measurement.

Here we present a measurement device and a biochip developed at the Walter Schottky In-stitute for the parallel and label-free detection and analysis of biomolecules. The utility of the switchSENSE platform for the analysis of protein-protein, protein-DNA, DNA-DNA is demon-strated and application examples with relevance to the engineering of therapeutic antibodies are presented.


Poster P

resentatio

ns

Bio

-Nan

osc

ien

ce

Protein Binding Assays in Biological Liquids using Microscale ThermophoresisChristoph J. Wienken1, *, Philipp Baaske2, Stefan Duhr2 and Dieter Braun1

1 Department of Physics and Center for NanoScience (CeNS), Ludwig Maximilians University Munich, Amalienstr. 54, 80799 Munich Germany

2 NanoTemper Technologies GmbH, Amalienstr. 54, 80799 Munich, Germany* Christoph Wienken, email: [email protected], phone: +49 89 2180 1484, fax: +49 89 2180 16558

Protein interactions inside the human body are expected to differ from the situation in vitro. This is crucial when investigating protein functions or developing new drugs. We present

a sample-effi cient, free-solution method termed Microscale Thermophoresis (MST) that is ca-pable of analyzing interactions of proteins or small molecules directly in biological liquids such as blood serum or cell lysate. The technique is based on the thermophoresis of molecules, which provides information about molecule size, charge and hydration shell. We validated the method using immunologically relevant systems like human interferon gamma or low molecu-lar weight binders such as calcium binding to calmodulin. The affi nity of the small molecule inhibitor quercetin for its kinase PKA was determined in buffer and human serum revealing an 400-fold reduced affi nity in serum. This information about infl uences of the biological matrix allows for more reliable conclusions on protein functionality and may aid in more effi cient drug development.


Bio

-Nan

osc

ien

ce

Formation of Nanoparticle Structures with a Combination of Protein and DNA LinkersVera B. Zon, Matthias Sachsenhauser and Ulrich RantWalter Schottky Institut, Technische Universität München, 85748 Garching, Germany

The optical properties of metal nanoparticles (NPs) are governed by localized surface plas-mon resonances (LSPRs), which result from the interaction of the conduction electrons of

the particles with the incident light. The coupling of LSPRs between closely located colloidal metal particles is particularly interesting, because it generates substantial enhancements of the electric fi eld, so called ‘hot spots’, which may be used for surface-enhanced spectroscopy or engineered for energy-transfer constructs. In order to build complex architectures with tailored optical properties (optical circuits) from individual NPs, the protein- and/or DNA-programmed assembly of NPs is especially promising, because particles can be deterministically arranged on the nano-scale.

Here we present a controlled way to form gold NP dimers and to build chains from the dimers. The chain units are protein-linked NP dimers, which are connected by DNA molecules. We utilize the self-organizing properties of DNA, which allow us to pre-design the desired struc-tures and arrange the building blocks in a deterministic manner. We show the infl uence of the number of the DNA strands per linking protein on the architecture of the obtained structures. The system is examined with respect to its optical properties with UV-VIS spectroscopy and dynamic light scattering; additionally we present TEM images of the NP complexes.


PUBLIC TRANSPORT

Subway „U6“, direction „Garching Forschungszentrum“

Departure „Marienplatz“ (Munich city center) 7:40 7:50 8:00

Departure „Garching“ (Hotel König Ludwig) 8:03 8:13 8:23

Arrival „Garching Forschungszentrum“ 8:05 8:15 8:25

Subway station - IAS building: 5 min walk,

Subway station - ZNN building: 10 min walk

ORGANIZERS

Nanosystems Initiative Munich (NIM) & TUM Institute for Advanced Study (IAS): G. Abstreiter, H. Dietz, J.J. Finley, D. Grundler, A. Holleitner, P. Lugli, F. Simmel, M. Stutzmann

CONTACT

Irmgard Neuner (Offi ce Prof. Gerhard Abstreiter)Walter Schottky Institut (TU München)Am Coulombwall 3D-85748 GarchingTel: +49-(0)89-289-12771Fax: +49-(0)[email protected]

ZNNCenter for Nanotechnologyand Nanomaterials, Am Coulombwall 4

IASInstitute for Advanced Study (Lichtenbergstraße/Boltzmannstraße)

Subway station„GarchingForschungszentrum“

USEFUL INFORMATIONHow to get to the venue


LIST OF PARTICIPANTS

First Name Last Name Affi liation e-mail

Yasuhiko Arakawa University of Tokyo [email protected]

Marianne Auernhammer TU München [email protected]

Erik Bakkers TU Delft [email protected]

Andreas Bausch TU München [email protected]

Heike Böhm Max Planck Institute for Metals Research [email protected]

Achyut Bora TU Braunschweig [email protected]

Dieter Braun LMU München [email protected]

Carlos Castro TU München [email protected]

Anna Cattani-Scholz TU München [email protected]

Hendrik Dietz TU München [email protected]

Beate Dirks TU München [email protected]

Georg Dürr TU München [email protected]

Klaus Ensslin ETH Zürich [email protected]

Jochen Feldmann LMU München [email protected]

Claudia Felser Johannes-Gutenberg-Universität Mainz felser-offi [email protected]

Jonathan Finley TU München jonathan.fi [email protected]

Matthias Firnkes TU München matthias.fi [email protected]

Anna Fontcuberta i Morral EPF Lausanne anna.fontcuberta-morral@epfl .ch

Emanuel Forster TU München [email protected]

Daniel Fuhrmann Universität Augsburg [email protected]

Stefan Funk TU München [email protected]

Jose A. Garrido TU München [email protected]

Hermann Gaub LMU München [email protected]

Thomas Gerling TU München [email protected]

Stephen Goodnick Arizona State University [email protected]

Dirk Grundler TU München [email protected]

Moritz Hauf TU München [email protected]

Norman Hauke TU München [email protected]

Simon Hertenberger TU München [email protected]

Lucas Hess TU München [email protected]

Nicolas Hoermann TU München [email protected]

Markus Hofstetter Helmholtz Zentrum München markus.hofstetter@helmholtz-muenchen

Alexander Högele LMU München [email protected]

Alexander W. Holleitner TU München [email protected]

John Howgate TU München [email protected]

Rupert Huber TU München [email protected]

Thorsten Hugel TU München [email protected]

David Hunger LMU München [email protected]

Anna-Lena Idzko Helmholtz Zentrum München [email protected]

Andreas Jöckel MPQ/LMU/Uni Basel [email protected]

Ralf Jungmann TU München [email protected]

Horst Kessler TU München [email protected]

Fabian Kilchherr TU München [email protected]

Florian Klotz TU München fl [email protected]

Gregor Koblmüller TU München [email protected]

Maria Korppi Universität Basel [email protected]

Jörg Kotthaus LMU München [email protected]

Joachim Krenn Karl-Franzens-Universität Graz [email protected]

Hubert Krenner Universität Augsburg [email protected]

Katharina Krischer TU München [email protected]

Julia Kunze TU München [email protected]


First Name Last Name Affi liation e-mail

Anton Kuzyk TU München [email protected]

Martin Langecker TU München [email protected]

Arne Laucht TU München [email protected]

Silvia Leonardi TU München [email protected]

Tim Liedl LMU München [email protected]

Enrique Lin Shiao TU München [email protected]

Bettina Lotsch LMU München [email protected]

Paolo Lugli TU München [email protected]

Thomas Martin TU München [email protected]

Christof Mast LMU München [email protected]

Bert Nickel LMU München [email protected]

Yoshichika Otani University of Tokyo [email protected]

Natan Osterman LMU München [email protected]

Milan Padilla TU München [email protected]

Anshuma Pathak TU Braunschweig [email protected]

Daniel Pedone TU München [email protected]

Leonhard Prechtel TU München [email protected]

Joachim Rädler LMU München [email protected]

Ulrich Rant TU München [email protected]

Celine Rüdiger TU München [email protected]

Daniel Rudolph TU München [email protected]

Benedikt Rupprecht TU München [email protected]

Matthias Sachsenhauser TU München [email protected]

Giuseppe Scarpa TU München [email protected]

Matthias Schickinger TU München [email protected]

Lukas Schmidt-Mende LMU München [email protected]

Christian Schönenberger Universität Basel [email protected]

Yvonne Schön Max Planck Institute for Metals Research [email protected]

Florian Schülein Universität Augsburg fl [email protected]

Alice Schwede Max Planck Institute for Metal Research Stuttgart [email protected]

Petra Schwille TU Dresden [email protected]

Max Seifert TU München [email protected]

Ian Sharp TU München [email protected]

Friedrich Simmel TU München [email protected]

Uri Sivan Technion Tel Aviv [email protected]

Martin Soini TU München [email protected]

Dance Spirkoska TU München [email protected]

Markus Stallhofer TU München [email protected]

Marin Steenackers TU München [email protected]

Frank Stetter TU München [email protected]

Mathias Strackharn LMU München [email protected]

Ralf Strasser TU München [email protected]

Martin Stutzmann TU München [email protected]

Almut Tröller LMU München [email protected]

Klaus von Klitzing MPI für Festkörperforschung, Stuttgart [email protected]

Christian Wachauf TU München [email protected]

Eva Weig LMU München [email protected]

Christian Westermeier LMU München [email protected]

Wolfgang Wiedemann LMU München [email protected]

Christoph Wienken LMU München [email protected]

Andreas Wild TU München [email protected]

Marc Wilde TU München [email protected]

Achim Wixforth Universität Augsburg [email protected]

Jörg Wrachtrup Universität Stuttgart [email protected]

Ilaria Zardo TU München [email protected]

Vera Zon TU München [email protected]

PR

OG

RA

M – M

ON

DA

Y, O

CT

OB

ER

25, 2010

8:30-9:00 O

PE

NIN

G A

ND

WE

LCO

ME

AD

DR

ES

SE

S

SE

SS

ION

1: Q

UA

NT

UM

NA

NO

SY

ST

EM

S

VE

NU

E: IA

S B

UIL

DIN

G

9:00-9:40 K

laus vo

n K

litzing

(MP

I für F

estkörp

erforsch

un

g, S

tuttg

art) E

xperiments on the ultim

ate two-dim

ensional electron system

9:40-10:10 K

laus E

nsslin

(ET

H Z

ürich

)G

raphene quantum circuits

10:10-10:40 C

OF

FE

E B

RE

AK

10:40-11:00 Jo

nath

an F

inley (T

U M

ün

chen

and

NIM

)E

xploring and harnessing cavity-QE

D phenom

ena in single and few

quantum dot photonic crystal nanostructures

11:00-11:30 E

rik Bakkers (T

U D

elft)P

eriodic Nanow

ire Structures

11:30-12:00 A

nn

a Fo

ntcu

berta i M

orral (E

PF

Lau

sann

e and

TU

M-IA

S)

Ga-assisted M

BE

grown G

aAs nanow

ires and related quantum

heterostructures for solar applications

12:00-13:30 LU

NC

H B

RE

AK

SE

SS

ION

2: H

YB

RID

NA

NO

SY

ST

EM

S

VE

NU

E: IA

S B

UIL

DIN

G

13:30-14:00 E

va Weig

(LM

U M

ün

chen

and

NIM

)V

oltage-sustained self-oscillation of a nanomechanical electron shuttle

14:00-14:30 C

hristian

Sch

ön

enb

erger (U

niversität B

asel)C

ooper-pair splitter: towards an effi cient source

of spin-entangled EP

R pairs

14:30-15:00 Y

osh

ichika O

tani (U

niversity o

f To

kyo)

Pure spin current based spintronics in m

etallic nano-structures

15:00-15:30 Jö

rg W

rachtru

p (U

niversität S

tuttg

art)C

arbon nanostructures for quantum spintronics

15:30-16:00 C

OF

FE

E B

RE

AK

16:00-16:30 Jo

achim

Kren

n (U

niversität G

raz)P

lasmonic control of elem

entary emitters

16:30-17:00 A

chim

Wixfo

rth (U

niversität A

ug

sbu

rg an

d N

IM)

The perfect w

ave

17:00-17:30 A

lexand

er Ho

lleitner (T

U M

ün

chen

and

NIM

)O

ptoelectronic dynamics in hybrid nanoscale circuits

17:30-18:00 Y

asuh

iko A

rakawa (U

niversity o

f To

kyo an

d T

UM

-IAS

)A

Quarter C

entury of Quantum

Dots: F

rom S

cience to P

ractical Implem

entation

18:15-19:00 R

EC

EP

TIO

N

19:00-22:00 D

INN

ER

PR

OG

RA

M – T

UE

SD

AY

, OC

TO

BE

R 26, 2010

SE

SS

ION

3: N

AN

O A

ND

EN

ER

GY

V

EN

UE

: IAS

BU

ILD

ING

8:30-9:00 M

artin S

tutzm

ann

(TU

Mü

nch

en an

d N

IM)

„Black S

ilicon“: Nanotextured S

ilicon Surfaces for P

hotovoltaics

9:00-9:30 S

teph

en G

oo

dn

ick (Arizo

na S

tate Un

iversity)R

ole of Nanotechnology in T

hird Generation P

hotovoltaics

9:30-10:00 L

ukas S

chm

idt-M

end

e (LM

U M

ün

chen

and

NIM

)N

anostructured organic and hybrid solar cells

10:00-10:30 C

OF

FE

E B

RE

AK

10:30-11:00 C

laud

ia Felser (U

niversität M

ainz)

Heusler C

ompounds: N

ovel Materials for E

nergy Applications

11:00-11:30 Ju

lia Ku

nze (T

U M

ün

chen

and

IAS

)T

iO2 -N

anotubes in Energy R

esearch

11:30-14:30 P

OS

TE

RS

ES

SIO

N A

ND

BU

FF

ET

-LU

NC

H

VE

NU

E: Z

NN

BU

ILD

ING

SE

SS

ION

4: B

IO-N

AN

OS

CIE

NC

E

VE

NU

E: IA

S B

UIL

DIN

G

14:30-15:00 P

etra Sch

wille (T

U D

resden

)S

ynthetic Biology of C

ell Division

15:00-15:30 H

end

rik Dietz (T

U M

ün

chen

and

IAS

)D

NA

Nanotechnology for P

rotein Science

15:30-16:00 U

ri Sivan

(Tech

nio

n, Israel)

The B

io-Electronic S

ynapse – Fusing E

lectronics with M

olecular Biology

16:00-16:30 C

OF

FE

E B

RE

AK

16:30-17:00 U

lrich R

ant (T

U M

ün

chen

, NIM

and

IAS

)M

olecular Interactions on Dynam

ically Actuated S

urfaces and in A

rti fi cial Nanopores

17:00-17:30 Jo

achim

Räd

ler (LM

U M

ün

chen

and

NIM

)S

tochastic gene expression and the decisive role of noise in m

icrobial genetic networks

17:30-18:00 F

riedrich

Sim

mel (T

U M

ün

chen

and

NIM

)N

anoscale structures and molecular devices m

ade from D

NA

18:00-19:00 C

LOS

ING

AN

D F

AR

EW

ELL (B

IER

AN

D B

RE

ZE

N)

VE

NU

E

TU

M Institute for A

dvanced Study (IA

S) and

Center for N

anotechnology and Nanom

aterials (ZN

N) of W

alter Schottky Institut in G

arching

OR

GA

NIZ

ER

S

Nanosystem

s Initiative Munich and T

UM

Institute for Advanced S

tudyG

erhard Abstreiter, H

endrik Dietz, Jonathan J. F

inley, Dirk G

rundler, A

lexander Holleitner, P

aolo Lugli, Friedrich S

imm

el, Martin S

tutzmann

Documents

International Symposium on Advances in Nanoscience · International Symposium on Advances in Nanoscience October 25-26, 2010 Campus Garching Center for Nanotechnology and Nanomaterials