The Gaas/Gainp2 Heterojunction For Studying Photoinduced Charge Transfer Processes

We report on a novel semiconductor photoelectrode structure that exhibits a dependence of the photocurrent-voltage characteristics an the concentration of a nonadsorbed, outer-sphere redox acceptor. The structure consists of a thin (30-50 Angstrom) epilayer of GaInP2 grown on a thick (5000 Angstrom)p-GaAs epilayer. The thin GaInP2 layer produces very good passivation of the GaAs surface resulting in surface recombination velocities less than 200 cm/s, while al the same time permitting efficient electron transfer, presumably via field-assisted tunneling and/or thermionic emission.