Effect of Ag addition on the photoconductivity of amorphous Se–Sb thin films

Amorphous thin films of Se80−xSb20Agx (0≤x≤16) have been prepared by a thermal evaporation technique. The dark conductivity and the photoconductivity of Se80−xSb20Agx (0≤x≤16) thin films have been determined. Dark conductivity increases with the increase in the silver content. The photoconductivity of these films has been studied at different illumination intensities. With illumination the photocurrent increases initially with time and then saturates at a constant value for low intensities of light (<400 lx), however, with higher intensities (>600 lx) the photocurrent increases initially, attains a maximum, and then decreases with time. The results have been explained on the basis of the Dember voltage and the interaction between the photogenerated holes and the trapped electrons on the surface. The variation of photocurrent with illumination intensity indicates that the recombination mechanism is bimolecular. The photosensitivity of these samples lies between 2.06 and 3.50.