Comparison of Direct Growth and Wafer Bonding for the Fabrication of GaInP/GaAs Dual-Junction Solar Cells on Silicon

摘要

Two different process technologies were investigated for the fabrication of high-efficiency GaInP/GaAs dual-junction solar cells on silicon: direct epitaxial growth and layer transfer combined with semiconductor wafer bonding. The intention of this research is to combine the advantages of high efficiencies in III–V tandem solar cells with the low cost of silicon. Direct epitaxial growth of a GaInP/GaAs dual-junction solar cell on a GaAs $_{y}$P$_{1-y}$ buffer on silicon yielded a 1-sun efficiency of 16.4% (AM1.5g). Threading dislocations that result from the 4% lattice grading are still the main limitation to the device performance. In contrast, similar devices fabricated by semiconductor wafer bonding on n-type inactive Si reached efficiencies of 26.0% (AM1.5g) for a 4-cm$^{2}$ solar cell device.