Toward High Performance N/P GaAs Solar Cells Grown on Low Dislocation Density p-Type SiGe Substrates

S. A. Ringel, C. L. Andre, M. K. Hudait, D. M. Wilt, E. B. Clark, A. J. Pitera, M. L. Lee, E. A. Fitzgerald, M. Carroll, M. Erdtmann, J. A. Carlin, B. M. Keyes

Research output: Contribution to conferencePaperpeer-review

6 Scopus Citations


GaAs solar cells grown on SiGe/Si virtual substrates in the n/p configuration are of interest to develop III-V/Si cell technologies with high radiation-tolerance and to demonstrate the general applicability of SiGe/Si substrates for transfer of standard multi-junction configurations. This paper reports the first study of minority carrier electron lifetimes in p-type GaAs base materials grown on low dislocation density (1×10 6 cm -2) SiGe/Si substrates and the first study of n/p III-V cells grown on SiGe as a function of threading dislocation density. Minority carrier diffusion lengths of ∼4 μn, well in excess of a typical n/p cell base thickness, are demonstrated and correlations between diffusion length and dislocation density are made. Preliminary cell results match theoretical predictions, and n/p GaAs cell efficiencies on Si in excess of 15% have been achieved. In parallel developments for p/n cells, GaAs cell areas on SiGe have been increased from 0.36 cm 2 to 4 cm 2 with no decrease in cell performance. This indicates that thermal stress induced microcracks are not limiting cell performance on SiGe/Si substrates at this stage of development. The cumulative impact of these results indicate the growing promise of SiGe virtual substrates for achieving high performance III-V solar cells grown on Si substrates utilizing SiGe buffer layers.


Conference3rd World Conference on Photovoltaic Energy Conversion (WCPEC-3): Joint Conference of 13th PV Science and Engineering Conference, 30th IEEE PV Specialists Conference, and 18th European PV Solar Energy Conference
CityOsaka, Japan

NREL Publication Number

  • NREL/CP-520-36513


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