Anomalous Photoconductive Transport Properties of As2Se3 Films

Abstract

Se 3 films have been prepared by the thermal evaporation technique. The variation of the photocurrent with the temperature at different illumination intensities showed that the behavior is thermally activated with photocurrent activation energy that increased from 0.18 to 0.3 eV as a function of light intensity. The thermal activation energy of the dark current was found to be 0.86 eV (about half of the band gap of As 2 Se 3). An anomalous behavior has been observed in the photocurrent light intensity as a function of temperature. The photocurrent I ph changes as the light intensity I α. For low light intensity, 0.58 < α < 0.71 while at high light intensity the exponent α was found to be greater than unity. On the other hand, the thermal stimulated depolarization current (TSDC) spectrum, under dark and pre-illumination conditions, is measured and the results were correlated with the change of the energy configuration of the defect states in the material under investigation.