Investigations of High-Performance GaAs Solar Cells Grown on Ge–Si$_1-xhbox Ge_ x$–Si Substrates
- 23 May 2005
- journal article
- Published by Institute of Electrical and Electronics Engineers (IEEE) in IEEE Transactions on Electron Devices
- Vol. 52 (6), 1055-1060
- https://doi.org/10.1109/ted.2005.848117
Abstract
High-performance p/sup +//n GaAs solar cells were grown and processed on compositionally graded Ge-Si/sub 1-x/Ge/sub x/-Si (SiGe) substrates. Total area efficiencies of 18.1% under the AM1.5-G spectrum were measured for 0.0444 cm/sup 2/ solar cells. This high efficiency is attributed to the very high open-circuit voltages (980 mV (AM0) and 973 mV (AM1.5-G)) that were achieved by the reduction in threading dislocation density enabled by the SiGe buffers, and thus reduced carrier recombination losses. This is the highest independently confirmed efficiency and open-circuit voltage for a GaAs solar cell grown on a Si-based substrate to date. Larger area solar cells were also studied in order to examine the impact of device area on GaAs-on-SiGe solar cell performance; we found that an increase in device area from 0.36 to 4.0 cm/sup 2/ did not degrade the measured performance characteristics for cells processed on identical substrates. Moreover, the device performance uniformity for large area heteroepitaxial cells is consistent with that of homoepitaxial cells; thus, device growth and processing on SiGe substrates did not introduce added performance variations. These results demonstrate that using SiGe interlayers to produce "virtual" Ge substrates may provide a robust method for scaleable integration of high performance III-V photovoltaics devices with large area Si wafers.Keywords
This publication has 13 references indexed in Scilit:
- Impact of dislocations on minority carrier electron and hole lifetimes in GaAs grown on metamorphic SiGe substratesApplied Physics Letters, 2004
- Impact of threading dislocations on both n/p and p/n single junction GaAs cells grown on Ge/SiGe/Si substratesPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2003
- Experimental study of solar cell performance versus dislocation densityPublished by Institute of Electrical and Electronics Engineers (IEEE) ,2002
- Single‐junction InGaP/GaAs solar cells grown on Si substrates with SiGe buffer layersProgress in Photovoltaics: Research and Applications, 2002
- Impact of GaAs buffer thickness on electronic quality of GaAs grown on graded Ge/GeSi/Si substratesApplied Physics Letters, 2000
- Controlling threading dislocation densities in Ge on Si using graded SiGe layers and chemical-mechanical polishingApplied Physics Letters, 1998
- High efficiency indium gallium arsenide photovoltaic devices for thermophotovoltaic power systemsApplied Physics Letters, 1994
- Numerical analysis for high-efficiency GaAs solar cells fabricated on Si substratesJournal of Applied Physics, 1989
- Growth and characterization of Si1−xGex and Ge epilayers on (100) SiJournal of Applied Physics, 1988
- Efficiency calculations of thin-film GaAs solar cells on Si substratesJournal of Applied Physics, 1985