Water-vapor-mediated close-spaced vapor transport growth of epitaxial gallium indium phosphide films on gallium arsenide substrates

Ga1–xInxP is a technologically important III–V ternary semiconductor widely utilized in commercial and record-efficiency solar cells. We report the growth of Ga1–xInxP by water-vapor-mediated close-spaced vapor transport. Because growth of III–V semiconductors in this system is controlled by diffusion of metal oxide species, we find that congruent transport from the mixed powder source requires complete annealing to form a single alloy phase. Growth from a fully alloyed source at water vapor concentrations of ∼7000 ppm in H2 at 850 °C affords smooth films with electron mobility of 1070 cm2 V–1 s–1 and peak internal quantum efficiency of ∼90% for carrier collection in a nonaqueous photoelectrochemical test cell.