Effect of hydrogen on the photoelectric properties of palladium/anodic oxide/gallium arsenide Schottky diodes

The effect of hydrogen on the photovoltage and I-V characteristics of palladium/anodic oxide/gallium arsenide Schottky diodes is studied. The oxide thickness that is optimal in terms of the hydrogen sensitivity of the diodes and the depth of atomic hydrogen penetration into the oxide are determined. The mechanism behind the hydrogen effect consists in the chemical adsorption of atomic hydrogen on the gallium arsenide surface, which decreases the barrier height and increases the recombination component of the current. It is shown that a thin tunnel-transparent anodic oxide film is nonuniform in thickness and that hydrogen exposure raises the probability of tunneling through the oxide. It is found that the method of hydrogen detection from the photovoltage response offers a higher sensitivity and detectivity but has a lower speed than the reverse current method.