Photocurrent suppression and interface state recombination in MIS-Schottky barriers

The purpose of this work is to understand an important degradation mechanism in Schottky barrier photodetectors and solar cells. The I-V characteristics of Au-nSi devices under illumination show a pronounced photocurrent suppression at low voltages in the presence of an interfacial oxide layer of thickness ≥ 20 A (intentionally introduced) but no suppression in the case of a carefully prepared near-intimate contact. The analysis of these devices takes into account the exchange of charge carriers between interface states and the metal (by tunneling) and between these states and the conduction and valence bands in the semiconductor. As suggested by the experiments, this shows that recombination in the interface states can be important only in the presence of a significant interfacial layer.