TRANSIENT PHOTOCONDUCTIVITY IN a-Se70Te30-xZnx THIN FILMS

Rise and decay of photoconductivity is studied in amorphous thin films of a-Se70Te30-xZnx (x = 0, 2, 4, 6 and 8) prepared by vacuum evaporation technique. These measurements at different temperatures and intensities indicate that the decay of photoconductivity is quite slow. A persistence photoconductivity is also observed. This is attributed to light induced effects in these materials. Photoconductivity decay, even after subtraction of persistent photoconductivity, is found to be non - exponential in the present case, indicating the presence of continuous distribution of defect states. Differential life time of execess carriers is calculated which supports the above argument.