Dark and Photoconductivity in a Se-Te-Pb Thin Films

Temperature dependence of conductivity is studied in a dark as well as in presence of light in amorphous thin films of Se₇₀Te_30-xPb_x (x = 0, 2, 6, 8) prepared by vacuum evaporation technique. Dark and Photoconductivity measurements were carried out on these films were characterized over the temperature range 250–350 K. The activation energy of photoconduction is found to decrease with increasing light intensity, which indicates illumination causes a shift in the Fermi level due to splitting of the Fermi level into quasi Fermi levels.