1. Symposium C2.2: Interface Design and Modelling
affiliations
date
Numerical and experimental ongoing on III-V/Si high-efficiency tandem solar cell
M. Da Silva1, S. Wang1, S. Almosni1, C. Cornet1, A. Létoublon1, C. Levallois1, A. Rolland1, J. Even1, L. Pedesseau1, P. Rale2, L. Lombez2, J.-F. Guillemoles2,3, and O. Durand1
UEB, INSA, FOTON, UMR CNRS 6082, Rennes, France
IRDEP, UMR CNRS-EDF-ENSCP, EDF R&D, Chatou, France
NextPV, LIA CNRS-RCAST/U. Tokyo-U. Bordeaux, Komaba, Meguro-ku, Tokyo, Japan
EUROMAT 2015:
Symposium C2.2: Interface Design and Modelling
23 September 2015

2. Outline
Motivation
GaP/Si: crystal growth developments, issues and strategies
GaP/Si: devices
Photovoltaics
Conclusion & Prospects

3. Motivation: III-V on silicon, many promises
III-V/Si
-Electronics Si
-HEMT technology
-Health/environment
-Lab on chip applications
-Integrated Biosensors
Liang et al., Nature photonics 167, 511 (2010).
Intel ©
-Energy
-Low cost and mature technology
-Limited mobility
-Indirect bandgap
-Photovoltaics
-Thermoelectricity
-Photonics
-Single low cost photonics devices (lasers, LEDs, telecom devices)
-Optical interconnects, on/off-chip

4. Motivation: Heterogeneous vs Monolithic
Monolithic integration
Heterogeneous integration
III-V or IV growth on Si
-group IV : Si-Raman lasers , strained Ge
-group III-V devices on Si or SiGe (metamorphic or pseudomorphic)
Bonding methods
-Dies or wafers
-InP and GaAs platforms
-Si/SiO2 passive photonics
Maturity
Substrate costs
alignments
Thermal
management

5. Motivation: The pseudomorphic approach5
Pseudomorphic growth
FOTON-OHM and CEMES (unpublished)
GaP
Metamorphic growth
dislocations engineering Si
28/11/2013
GaP/Si interface by HRTEM
Quasi lattice-matching
S.H.Huang et al., Appl. Phys. Lett. 93, (2008)

6. Motivation: Multijunction solar cells on silicon6
-High efficiency solar cells on low cost/scalable Si substrate
Applications
Current matching
ISS
Space
Weight/power < usual MJSC
1.7 eV
(GaP-based)
1.1 eV (Si)
CPV central
Scalability
J F Geisz and D J Friedman, Semicond. Sci. Technol. 17 (2002) 769–777
€ / Wp
Lattice-matched

7. GaP/Si: crystal growth developments, issues and strategies7
GaP/Si: crystal growth developments, issues and strategies

8. Issues and strategies 3D growth of GaP on Si (surface energies)8
3D growth of GaP on Si (surface energies)
-alternated growth Ga-P-Ga-P-Ga …
Micro-Twins, generated at the GaP/Si interface
-Clean interface
(contaminants-free)
-Influence of the first monolayer of GaP
Antiphase domains
-silicon bisteps
-initial Ga or P coverage

9. 9
GaP/Si: devices

10. GaAs0.1P0.88N0.02 : a lattice-matched alloy
GaP/Si: devices 10
The lattice-matched GaAsPN absorber
S. Almosni et al., J. Appl. Phys. 113, (2013)
S. Ilahi et al., Sol. Ener. Mat. and Sol. Cells. 141, 291 (2015)
GaAs0.1P0.88N0.02 : a lattice-matched alloy
Absorption around 1.8 eV

11. Efficiency far from the 15% expected
GaP/Si: devices 11
PV solar cells on GaP substrate
Device
I-V under AM1.5G
Efficiency far from the 15% expected
 Influence of absorber thickness : issue of carrier collection in dilute nitrides ?
S. Almosni et al., in preparation (2015)

12. Additional Shunt resistances BUT Good control of the GaP/Si interface
GaP/Si: devices 12
PV solar cells on Si substrate
Device
I-V under AM1.5G
GaPp
Absorber
GaPn
GaP buffer
Si substrate
Additional Shunt resistances BUT
Good control of the GaP/Si interface
Prospects
 Better carrier diffusion length in dilute nitrides alloys
 GaP(n++)/Si(p++) : the best tunnel configuration ?

13. GaP/Si: devices: Tunnel Junction, modeling13
A. Rolland et al., Opt. Quant. Electron. (2014)
(a) Schematic of the GaAsPN/Si tandem cell and (b) Simulated current-voltage characteristic of a GaP(n+)/Si(p+) and Si(n+)/Si(p+) tunnel junctions at uniform doping of ~5x1019cm-3

14. GaP/Si: devices: Tunnel Junction, modeling14
A. Rolland et al., Opt. Quant. Electron. (2014)
Simulated Band diagram of a GaP(n+)/Si(p+) and Si(n+)/Si(p+) tunnel junctions at uniform doping of 1020 cm-3 at thermal equilibrium.

15. GaP/Si: devices: Top Cell, modeling15
A. Rolland et al., Opt. Quant. Electron. (2014)
Current voltage characteristic of the GaP/GaAsPN/GaP cell for GaAsPN layer thicknesses ranging from 0.5 µm to 3 µm..

16. Summary 16
Low density of planar defects, and annihilated antiphase boundaries
Single GaAsPN solar cell grown on silicon
Material optimization is still needed to improve carrier mobilities and lifetimes.

17. III-V/Si high-efficiency tandem solar cell
affiliations
date
Thank you for your attention 17