Analysis of electrical conduction phenomena in highly photosensitive amorphous InxSb20 − xAg10Se70 (0 ≤ x ≤ 20) chalcogenide films

In this work the study of optical gap, dc conduction and photoconductivity for thermally evaporated amorphous InxSb20 − xAg10Se70 (0 ≤ x ≤ 20) chalcogenide films have been reported. The conductivity is thermally activated and dc activation energy increases from 0.25 to 0.34 eV with indium content for this quaternary system. Similar trends in the optical gap have also been observed. The value of pre-exponential factor revealed the conduction processes as hoping of charge carriers in localized states. The photosensitivity increases linearly with light intensity while its value is found to increase from 20.53 to 132.9 with x in the present system. Photocurrent versus light intensity follows the power law and reveals the dominant recombination process. The modelling of photocurrent decay to a stretched exponential function for different compositions and intensities of light has been studied. The value of both decay time constant and dispersion parameters are found to increase with indium concentration and light intensity. The observed results about the conduction processes are important for the development of low cost photodetectors and solar absorbers.