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Singapore-MIT Alliance Programme for

Advanced Materials in Micro- and Nano-SystemsFlagship Research Program

Annual Report

Nanotechnology on a Silicon Platform

Co-Chairs: Choi Wee Kiong (NUS) and Carl V. Thompson (MIT)

Faculty Associates: Dimitri Antoniadis (MIT), Yet-Ming Chiang (MIT), W.K. Chim (NUS), S.J. Chua (NUS/IMRE), Eugene Fitzgerald (MIT), K.P. Loh

(NUS), Nicola Marzari (MIT), K.L. Pey (NTU), Caroline Ross (MIT), Henry I. Smith (MIT), Francesco Stellacci (MIT), John Thong (NUS), C.C. Wong

(NTU), S.F. Yoon (NTU), Q. Zhang (NTU)

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Objective: Develop and demonstrate concepts and processes for assembling nanoscale materials in complex, deterministic patterns, in which they can be incorporated into complex patterns of devices.

• Our program was originally organized into thrusts on:NanolithographyTemplated Self-AssemblyChemically-Driven AssemblyField-Driven Assembly

with exploratory research on nanowire photonic devices and nanodot memory devices.

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• As our program has matured, advances in templated, chemically-driven and field-driven assembly, have been applied to organization of specific devices and device structures. We therefore now organize our program along the following themes:

Nanolithography and Templated Self Assembly Nanodots: Synthesis, Assembly, and Devices Nanowires: Synthesis, Assembly, and Devices Nanotubes: Synthesis, Assembly, and Devices

• The original research on assembly approaches continues within this revised structure, and the original milestones and deliverables have been retained.

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Templated-self-assembly:Long-range-ordered scaffolds for functional nanowire arrays

Self-assembled two-component colloidal

crystal, for photonic and phononic devices

Deep sub-lithographic assembly of lamella arrays for nanoscale patterning of in-plane wire arrays

Self-assembled Ge nanodots for memory devices

Chemically-directed dielectrophoretic

assembly of nanodots between electrodes

Some Assembly Examples from This Year

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Electrical Characterization of a Self-Assembled Si NW FET: Demonstration of Concept

•Templated assembly of catalyst and colloidal particles (Thompson, Choi, Chiang, Wong)• Vapor-liquid-sold wire growth (Pey, Fitzgerald, Choi, Antoniadis, Thompson) • Characterization and modeling (Antoniadis, Pey)• Cross-over research: catalyst assembly techniques

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1. Nanolithography and Templated Self Assembly

Methods for producing large areas of periodic structures with different length scales and different symmetries

Accomplished, further research ongoing

nanotlithography, templated assembly of periodic structures with and without controlled defects

In progress

Tools and procedures for use of SOBL (Scanning Optical Beam Lithography) and ZPAL for high-throughput, quick turn around techniques for production of complex patterns

This deliverable has been changed. A new approach based on modulation lithography in conjunction with ZPAL is being pursued instead

2. Chemically-Directed Assembly Methods for solubilizing nanotubes, metal nanoparticles, and semiconductor nanowires

Accomplished, further research ongoing

Methods for theoretical predictions of chemistries for versatile assembly and anchoring

Accomplished for carbon nanotubes. Further research ongoing

Development of lithographic methods to produce patterned self-assembled monolayers with resolution comparable or smaller than the nanomaterials

Accomplished.

Procedures for building and use of nanobreadboards In progress: recent breakthrough in pore clearing for conductive underlayers

Definition and demonstration of protocols for chemically directed assembly of specific devices and systems

Accomplished, but continued research in progress. nanodot single-electron devices

3. Engineered Nano-Dot Catalysts for Nano-Systems

Demonstrations of nanobreadboards for assembly and characterization of nanodevices

On track

Methods for creation of large-areas of ordered arrays of uniform nanotubes, wires, and dots.

Accomplished, but continued research ongoing: Ni nanowire arrays

Methodologies for high-resolution characterization of systems of nanostructures

On track

Fabrication of biosensor arrays On track (with CNT based sensors)

Growth and properties of semiconductor nanowire arrays, e.g. BN and MoS2.

On track, but so far with a focus on group IV and III-V semiconductor nanowires

Deliverable Updates:

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4. Ordered Nanoparticle Structures through Field-Assisted Colloidal Self-Assembly

Method for surface-moderated multi-component colloidal crystallization of complex nanostructures

On track: successful templating of single-component structure, successful untemplated growth of multi-component crystals

Method for field-driven self-assembly of colloidal systems on various substrates

Accomplished, but continued research underway: field-driven assembly of CNTs and Au nanoparticles

Design guidelines for the use of field and surface assistance in trapping, assembly, and controlled placement of colloidal nanoparticles

On track

5. Nanomaterials and Technology for Integrated Optical Devices

Semiconductor heterostructure nanoscience and nanoprocessing

On track: ZnO nanowires and devices on GaN

Exploratory structures and devices which may contain novel functionality

On track

6. Integrated Nanomaterials and Technology for Information Storage

A template for the synthesis of nanodot and nanowire In progress

Develop method for the growth of heterogeneous nanowires In progress

Memory devices based on nanodots with high-k dielectric layer

Still feasible, but under evaluation

Deliverable Updates:

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Outreach

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Outreach

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♦ Flagship research activities have been highly collaborative and have involved exchanges of visits of students and staff among all three universities.

♦ These research interactions have already led to many publications (36 journal articles, of which 22 are joint publications), and these interactions are expected to lead to an increasing number of joint publications in future years.

♦ Flagship research teams are expanded by students and postdocs with other support, research is often complimentary to research supported through other programs, both within the US and Singapore, and is therefore leveraged through this support other support.