1Croissance monolithique de composés III-V-N à azote Croissance monolithique de composés III-V-N à azote dilué sur substrats de Si et projet ANR MENHIRS dilué sur substrats de Si et projet ANR MENHIRS

O. Durand, S. Almosni, C. Robert, T. Nguyen Thanh, C. Cornet, A. Létoublon, C. Levallois, L. Pedesseau, J. Even, J.M. Jancu, N. Bertru, and A. Le CorreUniversité Européenne de Bretagne, INSA, FOTON-OHM, UMR 6082, F-35708 RENNES, FranceFabien Mandorlo, Mustapha LemitiINL, INSA de Lyon, Bâtiment Blaise Pascal, 7 avenue Jean Capelle, 69621 VILLEURBANNE CEDEX, FrancePierre Rale, Laurent Lombez, Jean-Francois GuillemolesInstitut de Recherche et Développement sur l'Energie Photovoltaïque (IRDEP), UMR 7174 - CNRS-EDF-ENSCP, EDF R&D, 6 quai Watier, 78401 Chatou Cedex, FranceEric Tea, Sana LaribiInstitut de Recherche et Développement sur l'Energie Photovoltaïque (IRDEP), UMR 7174 - CNRS-EDF-ENSCP, EDF R&D, 6 quai Watier, 78401 Chatou Cedex, FranceAnne PonchetCEMES-CNRS, Université de Toulouse, 29 rue J. Marvig BP 94347, 31055 Toulouse Cedex 4, FrancePaul Bellavoine, Philippe LaferriereHeliotrop SAS, Paris Innovation, 24 rue de l'Est, 75020 Paris, FranceFilip TuomistoAalto University School of Science and Technology, AALTO,Finland

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© Heliotrop

Cellules multijonctions à concentrationContexte énergétique: remplacer les cellules Si monojonctions(faible rendement: asymptote des couts: 1€/Wc pour les modules)

<1€/Wc 0,2 €/Wc

MENHIRS: the issues

Projet labellisée par le pôle « Advancity » (Ville & Mobilité Durable)

Also: GaPN/GaP/Si(001) pseudo-substrates (project JCJC ANR-Sinphonic)

Route to increase the efficiency

λc

λ< λc =>energy losses, heatingλ > λc => non-absorbed photons

issue 1: issue 2: thermalisation

Eg V

Abso

rptio

n

Photon

Electron

HoleThermalisation

Ehν

Thermalisation

Ehc/λEFn

EFp

AvailableEnergy

Simple junction:

Decreasing of Eg (GaSb, Ge):More thermalisation

Increasing of Eg (GaP): less absorption

Multijunction:

Eg1 V

Abs

orpt

ion

Electron

Hole

Ehν1

np

Ehc/λ1

Ehc/λ2

Ehc/λ3

Eg2

VAbs

orpt

ion

Electron

Hole

Ehν2

np

Eg3 V

Abs

orpt

ion

Electron

Hole

Ehν3

np

Ehc/λ3

Ehc/λ2

Ehc/λ3

bluegreen

red

Stacking of several junctions, each specialised in one solar spectrum part

blue green red

∑= OCTotalOC VVI

VOC 1

VOC 2

VOC 3

Multijunctions: usually, direct gap III-V materials

optimum:= « current matching »

Route to increase the efficiency

High-Efficiency multijunction III-V Solar cells

GaAs and Ge substrates Current/proven technology, lattice match

Tandem cells: GaInP/GaAs Triple junctions: GaInP/Ga(In)As/GeSous concentration

Two conditions:1) Current matching (optimum gaps and thicknesses)2) Lattice matching (same lattice parameter)

Very difficult to get both!!!

Current technology

Epitaxial growth (MBE, MOCVD)

Lattice-matchedBut: current mismatched (Ge: 0.67 eV ?: 1eV)

New efficiency record: 44% at 947 suns (AM0), 16th october 2012

Solar International:

1 eV cell !!!

GaInAsNSb (diluted nitride)

Current matchingand Lattice matching

Triple junctions: GaInP/GaAs/GaInAsNSb/GaAs

High-Efficiency multijunction III-V Solar cells

tandem cells III-V/Si lattice-matched

"Material considerations for terawatt level deployment of photovoltaics" ; A. Feltrin, A. Freundlich, Renewable Energy 33, 180 (2008).

Ge Concentration: 1.5 mg/kg

Issue: substrate costs

High-Efficiency multijunction III-V Solar cells

Optimal solution?Optimal solution?III–N–V semiconductors for solar photovoltaic applications, J F Geisz and D J Friedman, Semicond. Sci. Technol. 17 (2002) 769–777

GaAsPN: In-free, diluted-N, « direct » band-gap

To be developed (medium afficiency, low cost):

New technology:Si cheap, Large substrateGaP and Si: LM 0.4 %GaAsPN and Si: LM and 1.7 eVNo misfit dislocations

tande

m cells

High-Efficiency multijunction III-V Solar cells

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Coherent growth of III-V onto Si (MBE): Monocristalline thin layerstwo main stumbling blocks

Silicium

GaAsPN

Silicium (001) 4° 6°-off

GaP

Preliminary targeted

structure:(MBE growth)

Epitaxial growth of III-V onto silicon

GaP 2) efficient absorber: efficient absorber: second stumbling blocksecond stumbling block

1) GaP 20 nm/Si: first stumbling blockGaP 20 nm/Si: first stumbling block

GaAsPN: Diluted nitride (2-4%) GaAsPN: Diluted nitride (2-4%) lattice matched direct band lattice matched direct band

gap material gap material

10Defects at the GaP/Si interface

T

Typical Micro twin in a ZB

structure

Coherent growth

Defects at the interface: Micro twin (MT), stacking fault (SF), anti-phase domain (APD), misfit dislocation (MD), etc.

Growth of GaP/Si without Si bufferGrowth of GaP/Si without Si bufferT Nguyen Thanh et al, J. Appl. Phys. 112, 053521 (2012)

11GaP/Si interface: MicroTwins

TMicroTwins

Reciprocal space lattice

Signature of the MTs

Rotation axis

Rotation axis

Small domains of rotated cristal

Signature of the MTs

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TMicroTwins

Reciprocal space lattice

Signature of the MTs

Experimental XRD RSM around the (002) Bragg reflection (GaP 20 nm/Si(001) 4°-off)

Synchrotron, (ESRF)

GaP/Si interface: MicroTwins

N. BoudetCRG-D2AM, ESRF &Inst. Néel, CNRS-UJF, 25 Av

des Martyrs, 38042 Grenoble, France

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TMicroTwins

Reciprocal space lattice

Signature of the MTs

Synchrotron, (ESRF)

TEM Cross-section of GaP/Si – Tgrowth = 400°C (CEMES)

Quantification of the MTs with respect to the MBE growth conditions

Experimental XRD RSM around the (002) Bragg reflections

GaP/Si interface: MicroTwins

14

TC = 400°C

Micro-Twins

Optimisation de l’interface GaP20 nm/Si: réduction des Micro-Twins (MT)

GaP (004)

TC = 580°CGaP (004)

T Nguyen Thanh et al, J. Appl. Phys. 112, 053521 (2012)

A. Létoublon et al, J. of Cryst. Growth 323 (2011) 409–4123

W. Guo et al, Appl. Surf. Science 258 (2012) 2808– 2815

T Nguyen Thanh et al, Thin Solid Films (in press)

Defect density (MTs): decreases with the growth temperatureDefect density (MTs): decreases with the growth temperature

GaP/Si interface: MicroTwins

1515

a0/2

APDB APDAAPDB

Si (4°-off)Si (4°-off)

GaPGaP

ξAPD

III-V/Si issue: AntiPhase boundaries (Ga-Ga and P-P bonds)

GaP/Si interface: AntiPhase Domains (APDs)

Growth onto 4°-off or 6°-off Si(001) substrates:help to anhihilate the AntiPhase Domains (APDs) recombination centers (see poster P. Rale and E Tea)

Williamson-Hall plot (scans transverses)

O. Durand et al, Proc. SPIE 7940 79400L (2011).

X-Ray Diffraction

Defect density (APDs and MTs): decreases with the growth temperatureDefect density (APDs and MTs): decreases with the growth temperature

1616

٥ 2nd stumbling block: GaAsPN absorber

MENHIRS: first results

Light absorber around 1.7eV (GaP10 nm/ GaAsPN 100 nm/GaP(001))

Undoped structure PL: 1.74 eVat RT

Photoluminescence @RT(but very high Plaser ), λ=820 nm

Experimental results on GaAsPN/GaPN QWs onto Si(001)

AFM:RMS = 11.6nm

T. Nguyen Thanh et al, in press, J. of Cryst. Growth

I(V)Results:see poster P. Rale and E Tea

doped structure

1717

٥ Preliminary result (GaAsPN /GaPN) MQWs diode grown on GaP(001)

-0,4 -0,2 0,0 0,2 0,4 0,6 0,8 1,0 1,2 1,4 1,6-0,004

-0,003

-0,002

-0,001

0,000

0,001

0,002

0,003

0,004

Cur

rent

den

sity

(A/c

m²)

Voltage (V)

η = 1.6% without any concentration.Voc: goodISC: weak due to the small absorption volume.

absorption due to the MQWs

Contacts front and back surfaces: Ni/Au/AuZn and Ni/Au/Ge alloys.Front contact: annular (∅ = 300 µm, width = 20 µm)

see poster S. Almosni

Posters:P. Rale and E Tea (IRDEP): “Toward a III-V/Si tandem solar cell: characterization and modeling”S. Almosni (FOTON-INSA): “Evaluation of GaAsPN and InGaPN for photovoltaic (PV) applications”

MENHIRS: first results

AM1,5G

1818

٥ Conclusion

MENHIRS: Conclusion

Aim of MENHIRS: elaboration of a GaAsPN/Si tandem cell (1.7eV/1.1 eV)

First main issues:GaP/Si interface GaAsPN absorber

Preliminary (encouraging..) result: 1.6% efficiency on a (GaAsPN /GaPN) MQWs diode

Solid source MBE Riber Compact 21

UHV - LPCVD (Riber)+

Following issues:tunnel junctionSi junctionetc…

To be continued…

19

11/02/13

Tg = 350°C Tg = 450°C

= 11±1 nm ≡ APD

= 9.5±1 nm ≡ other defects = 23.7±0.2 nm

≡ all kind of defects

GaP/Si interface: AntiPhase Domains (APDs)

WHL-plots: slope WHL-plots: slope lateral « crystallite size » lateral « crystallite size »

Preliminary results:Preliminary results:higher growth temperature higher growth temperature larger crystallite sizes larger crystallite sizes

= lowering of the defects density= lowering of the defects densityBut:But:

Increasing of the surface roughness vs growth T°Increasing of the surface roughness vs growth T°