Impact of Buffer Architecture on the Performance of Heterogeneously Integrated III-V-on-Si Solar Cells

We have demonstrated the impact of buffer architectures on the performance of 1J GaAs solar cells heterogeneously integrated on Si. An all-epitaxial molecular beam epitaxy-grown thin (< 1 mu m) hybrid GaAs/Ge "virtual" buffer approach provided 1J GaAs cell efficiency of similar to 10% on Si, as compared with cell structures with thick 3 mu m GaAs buffers. Solar cell results were further corroborated with materials analysis to provide a clear path for the reduction of performance-limiting dislocations. The thin "Ge-on-Si" virtual buffer approach to III-V-on-Si cell structures in the current work indicates a promising future for monolithically integrated, low-cost and high-efficiency III-V-on-Si photovoltaics.