Middle Cell Development for Wafer-Bonded III-V//Si Tandem Solar Cells

This article focuses on the material properties of two III-V semiconductors, AlGaAs and GaInAsP, their usage as middle cell absorber materials in a wafer-bonded III-V//Si triple-junction solar cell. To this end single-junction cells were grown epitaxially lattice matched GaAs wafers using metalorganic vapor phase epitaxy. By optimizing growth temperature V/III ratio we could increase open-circuit voltage at target band gap 1.50 eV by up to 100 mV. In future these results will be implemented into two-terminal conversion efficiency beyond 35% under AM1.5g spectrum.