The GaAsGaInP2 heterojunction for studying photoinduced charge transfer processes

We report on a novel semiconductor photoelectrode structure that exhibits a dependence of the photocurrent-voltage characteristics on the concentration of a nonadsorbed, outer-sphere redox acceptor. The structure consists of a thin (30–50 Å) epilayer of GaInP2 grown on a thick (5000 Å) 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 at the same time permitting efficient electron transfer, presumably via field-assisted tunneling and/or thermionic emission.