Steady-state photoconductivity measurements were performed on a-Se78Ge22 thin films prepared by vacuum evaporation. The temperature dependence of the photocurrent showed a maximum at a high temperature. A clear transition from monomolecular to bimolecular recombination was also observed at the same temperature. The observed behaviour was explained by assuming two sets of defects of different capture cross-sections, and different time constants. The energy location of these sets of defects was determined from the experimental data. A superlinear dependence of photocurrent on intensity was observed in the films, which was explained in terms of the energy distribution of two discrete localized states with different cross-sections.

Determination of Energy of Defect Centres in a-Se78Ge22 Thin Films. N.Kushwaha, V.S.Kushwaha, R.K.Shukla, A.Kumar: Philosophical Magazine Letters, 2006, 86[11], 691-7