Photovoltage and photocurrent in Pd–oxide–InP structures in a hydrogen medium

Pd–oxide–InP (MOS) structures are fabricated, and their physical and photoelectric properties in a hydrogen atmosphere are investigated. It is established that a decrease in photovoltage of the structure and a large increase in photocurrent in the circuit are observed under the pulsed effect of hydrogen on the structure with a palladium layer illuminated by a light-emitting diode (LED of the wavelength λ = 0.9 μm). The kinetics and mechanism of the variation in the photovoltage and photocurrent are considered. It is assumed that the photovoltage decreases because of the ionization of hydrogen atoms in the Pd layer, and the photocurrent increases due to the thermionic emission of nonequilibrium electrons from the Pd layer into the semiconductor. On the basis of results of the investigations, the sensitive element for an optoelectronic hydrogen sensor is developed.