Nanowire solar cells

Novel optoelectronic

devices - GaAs

Research Highlights 2001-2010 – N. Pelekanos

Nitrides:Towards improved

optoelectronic devices

Piezoelectric quantum dots:

InAs (GaN)

Funding: EC, ΓΓΕΤ, ΥΠΕΠΘ,..., 2,9 million Euros

FORTH Microelectronics Research Group Univ. of Crete

PhD 1991: Brown Univ. (USA)

Post-docs: CEA/Grenoble, CNET Lannion, Max-Planck Stuttgart

1994-2001: CEA/Grenoble

2001-2010: FORTH & Univ. of Crete

Eliminate internal fieldsfor better blue lasers

Superior p-type contacts Integrated

HEMT on LED

Nitrides: Highlights

IST QN-Laser,IST QN-Laser IIG. Dialynas et al. JAP 2008

-4 -2 0 2 4-0.025

-0.020

-0.015

-0.010

-0.005

0.000

0.005

0.010

0.015

0.020

0.025

Ni/Au

RTA @500oC in air

10 m 18 m 26 m 34 m 42 m 50 m 58 m

curr

en

t (A

)

votage (V)

p-GaN/A/Bas-deposited

Cr/Au vs Ni/Au

F. Kalaitzakis, APL 2007

LED fabrication

NMP GaNano

Polarization engineering on InAlGaN/GaN quantum wells can give zero-field nitride optoelectronic devices.

But, the optoelectronic quality of InAlGaN has to be further improved.

360 380 400 420 440

#347

#346

4nm

In0.14

Al0.25

Ga0.61

N/GaN QWs

8nm

GaN-related

Pho

tolu

min

esce

nce

(a.u

.)

Wavelength (nm)325nm, 17K

Polariton LEDs and LasersPiezoelectric laser diodes

Tunable laser diodes

Novel optoelectronic devices: Highlights

Jth(111) < Jth(100)

G. Deligeorgis, APL 2007 901 902 903 904 905 906 907 908

laser10nm TQW

Inte

nsity

(ar

b.un

its)

Wavelength (nm)

p-side

CB B1 B2

VB

IST Tune-laser APL 2002, APL 200320nm tuning at low T, 5nm tuning at 300K

190

200

210

220

230

240

250

260

1.3601.3551.3501.3451.3401.3351.330

-S. Tsintzos, Nature 2008

-RT operation, S. Tsintzos, APL 2009.

T=235K

VV

Piezoelectric quantum dots: Highlights

+ + + + +

- - - - - - - - - - - - -

+

+

+

+++

e

h

InAs (211)B QDs

G. Dialynas, JAP 2010

G. Dialynas, to be submitted

Reference QW InAs QDs

1.2812 1.2813 1.2814 1.2815 1.2816Energy (eV)

T=8KV H

XInte

nsity

(a.u

.)

1.2844 1.2845 1.2846 1.2847 1.2848 1.2849

Energy (eV)

T=8K

XX

VH

Very small FSS. Promising for sources of entangled photons

Single photon emission; possibility for high-T operationAnti-binding biexciton energy

1.272 1.273 1.274 1.275 1.276 1.277

T=8K

XX

X

Inte

nsity (a.u

)

Energy (eV)

Single dot spectroscopy

Piezoelectric quantum dots: Highlights

S. Germanis, APL 2011

Project: III-V Nanowires for high efficiency Solar cells

Solar Innovation 2010 Awardby

Commissariat a l’ Energie Atomique

Why Nanowires for Solar Cells?

Potential for lower cost and high efficiency:

- enhanced light absorption, less material utilization- no need for lattice matching, easier choice of substrate & more freedom in heterostructure design- direct path for charge transport

“nanowire solar cells”

3 year project