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Electrically-DrivenOptical Antennas
René Kullock, Johannes Kern, Jord Prangsma and Bert Hecht
V+
hν
J.C. Prangsma et al., Electrically connected resonant optical antennas, Nano Lett. (2012)
50 nm
Motivation
2
On-chip data communication
Ultra-high density displays
Spectroscopic applicationsV+
hν
50 nm
How to Generate Light?
3
Processes:
- thermal
- electronic transitions
How to Generate Light?
4
Processes:
- thermal
- electronic transitions
- Inelastic electron tunneling
-> “Just” a tunnel gap is needed
Fabrication of the Tunnel Gap
5
cu
rren
t (a
.u.)
0
1
distance (nm)
0 2 4 6 8 10
Requirements:
- 1-3 nm gap width
- Atomic-scale stability
Fabrication of the Tunnel Gap
66
Requirements:
- 1-3 nm gap width
- Atomic-scale stability
Ga-Ion Focused Ion Beam Milling:
- Single-crystalline gold flakes
- Resolution limit around 15 nm
- Leakage currents
Solution:
- Stable 1-nm gaps for CTAB decorated nanoparticles
Fabrication of the Tunnel Gap
7J. Huang et al., Atomically flat single-crystalline gold nanostruct. for plasmonic nanocircuitry, Nature Com. (2010)
J.C. Prangsma et al., Electrically connected resonant optical antennas, Nano Lett. (2012) 7
Requirements:
- 1-3 nm gap width
- Atomic-scale stability
Ga-Ion Focused Ion Beam Milling:
- Single-crystalline gold flakes
- Resolution limit around 15 nm
- Leakage currents
Solution:
- Stable 1-nm gaps for CTAB decorated nanoparticles 1 nm20 nm
a b
J. Kern et al., Atomic-scale confinement of resonant optical field, Nano Lett. (2012)
Fabrication of the Tunnel Gap
8
New Approach:
- Pushing CTAB decorated nanoparticle into the antenna gap
CTABCetrimonium bromide
Results
9
- Nanometer-scale gap formed
- Tunneling characteristics
- Particle positioned asymmetrically
-> only one significant contact
linear tunneling regime
field emission regime
VT
~1 GV/m
~100 Ω
500 nm
- Light detected: 500…1000 nm
- Typical spot sizes: 300…400 nm
-> Electrically-driven point source!
Electroluminescence (EL)
10
350 nm
1000
500
0
-500
-1000
Influence of the Antenna
- EL is shaped by the antenna resonance
WL scattering
Exp Model
0
2
4
6
8
0
5
10
15
20
Wavelength (nm)
500 600 700 800 900 1000
Energy (eV)2.4 2.2 2 1.8 1.6 1.4
EL in
ten
sity
(10
3P
ho
ton
/s)
Scat
teri
ng
amp
litu
de
(%
)
1.7V1.8V1.9V2.0V
Influence of the Antenna
- EL is shaped by the antenna resonance
- QE up to 100x enhanced
- Polarized emission
- Dipolar emission pattern
12
Modelling?
- How to understand the light-emission process?
- And the spectral shift?
Modelling: Quantum shot noise
electrons in
electrons in
electrons reflected
electrons trans
+ -
electrons in
electrons reflected
electrons trans
+-
Modelling: Quantum shot noise
electrons in
electrons in
electrons reflected
electrons trans
Hone, Muhlschlegel, and Scalapino, Appl. Phys. Lett. 33, 203 (1978).P. Johansson, Physical Review B 58, 10823 (1998).Schneider, Schull, and Berndt, Phys. Rev. Lett. 105, 026601 (2010).
current power spectrum:
𝐼 𝜔 = 𝐴 𝜔 𝐶(𝜔)
Modelling: Quantum shot noise
current power spectrum:
Wavelength (nm)
1000
3.0V
2.0V1.9V
1.8V
1.7V
Cu
rre
nt
Po
we
rx
Lore
ntz
ian
(a.u
. )
0
1
2
3
4
5
No
rma
lize
dsc
a tte
rin
ga
mp
litu
de
0
1
Wavelength (nm)
500 600 700 800 900 1000
Energy (eV)
2.4 2.2 2 1.8 1.6 1.4
WL spectrumLorentzian fit
2.0V
1.9V
1.8V
1.7V
3.0 V
x 0.39
Cu
rre
nt
Po
we
rS
pe
c tru
m
0
0.2
0.4
0.6
0.8
1
500 600 700 800 900
Energy (eV)2.4 2.2 2 1.8 1.6 1.4
Hone, Muhlschlegel, and Scalapino, Appl. Phys. Lett. 33, 203 (1978).P. Johansson, Physical Review B 58, 10823 (1998).Schneider, Schull, and Berndt, Phys. Rev. Lett. 105, 026601 (2010).
𝐼 𝜔 = 𝐴 𝜔 𝐶(𝜔)
Modelling: Quantum shot noise
current power spectrum:
Wavelength (nm)
1000
3.0V
2.0V1.9V
1.8V
1.7V
Cu
rre
nt
Po
we
rx
Lore
ntz
ian
(a.u
. )
0
1
2
3
4
5
No
rma
lize
dsc
a tte
rin
ga
mp
litu
de
0
1
Wavelength (nm)
500 600 700 800 900 1000
Energy (eV)
2.4 2.2 2 1.8 1.6 1.4
WL spectrumLorentzian fit
2.0V
1.9V
1.8V
1.7V
3.0 V
x 0.39
Cu
rre
nt
Po
we
rS
pe
c tru
m
0
0.2
0.4
0.6
0.8
1
500 600 700 800 900
Energy (eV)2.4 2.2 2 1.8 1.6 1.4
Hone, Muhlschlegel, and Scalapino, Appl. Phys. Lett. 33, 203 (1978).P. Johansson, Physical Review B 58, 10823 (1998).Schneider, Schull, and Berndt, Phys. Rev. Lett. 105, 026601 (2010).
Conclusion- Built an electrically-driven subwavelength light source
- Connected nanoantenna + functionalized particle
- Light emission governed by the antenna
- QE enhanced by up to 100x
- Quantum shot noise
Outlook- Directed emission via Yagi-Uda antennas
- Improve stability, QE, …
- Launch propagating plasmons
- Usable for field-induced non-linearity
100 nm
Ack
no
wle
dge
me
nts Electrode Structures Monika Emmerling
Flake Transfer Heiko Groß
Flake Growth Xiaofei Wu
Enno Krauss
FIB Provider Martin Kamp
Connected Antennas Jord Prangsma
Pushing Johannes Kern
Optics Swen Großmann
Bert Hecht
Johannes Kern
Jord Prangsma
1 µm
10 µm
100 µm
1 mm
10 nm1 nm
http://arxiv.org/abs/1502.04935
