TRAPPING OF MINORITY CHARGE-CARRIERS AT IRRADIATED SEMICONDUCTOR/ELECTROLYTE HETEROJUNCTIONS

Photocatalytic reactions at irradiated semiconductor/electrolyte heterojunctions are usually assumed to involve the injection of minority charge carriers from the band edge of the semiconductor into dopant or defect states of the electrolyte. If corrosion is avoided by some coating, it is suggested as a hypothesis that charge injection into energy states above that corresponding to the band edge would be possible due to confinement and trapping of minority charge carriers in the depletion region. The proposed model takes quantization effects, surface states and tunnelling processes into account and predicts qualitatively the ''illumination-current'' characteristic curve. Photocatalytic reactions at coated n-GaAs/electrolyte junctions are discussed within the framework of the model.