Steady-state and transient photoconductivity in amorphous thin films ofGexSe100−x

The present paper reports the steady-state and transient photoconductivity (${\sigma }_{\mathrm{ph}}$) in amorphous thin films of ${\mathrm{Ge}}_{\mathrm{x}}$ ${\mathrm{Se}}_{100\mathrm{-}\mathrm{x}}$. It is observed that the photosensitivity (${\sigma }_{\mathrm{ph}/{\sigma }_d}$) shows a maxima at x=22. A study of the decay of photocurrent with time shows that the decay is fastest at the same composition. The results indicate that the defect states are minimum for x=22, which is explained in terms of chemical ordering because of noncrystalline compound (${\mathrm{GeSe}}_4$) formation as suggested by Feltz et al. [J. Non-Cryst. Solids 55, 179 (1983)].