Gallium arsenide phosphide grown by close-spaced vapor transport from mixed powder sources for low-cost III-V photovoltaic and photoelectrochemical devices

We report the heteroepitaxial growth of variable composition n-GaAs 1− x P x directly on GaAs substrates via close-spaced vapor transport using mixed GaAs-GaP powder sources. GaAs 1− x P x films showed an average 10% reduction in atomic concentration of phosphorous from the source material, and ten GaAs 0.7 P 0.3 films were grown with reproducible composition from a single source pellet. Non-aqueous photoelectrochemical measurements were used to assess electronic quality, with the best short-circuit photocurrent of 6.7 mA cm −2 and open-circuit photovoltage of 0.915 V for n-GaAs 0.7 P 0.3 with a carrier concentration of 2 × 10 17 cm −3 . The best Hall electron mobility for this composition was 1570 cm 2 V −1 s −1 . Cross-sectional transmission electron microscopy of GaAs 0.7 P 0.3 shows single-crystal structure with few defects. We conclude that CSVT is a promising route to the growth of ternary III-V materials like GaAs 1− x P x for low-cost high-efficiency tandem photoelectrochemical or photovoltaic devices. Close-spaced vapor transport provides GaAs 1− x P x with controlled composition and competitive electronic properties.