PHOTOCONDUCTIVITY IN AMORPHOUS THIN-FILMS OF GE22SE78-XBIX

Temperature and intensity dependence of photoconductivity is studied in amorphous thin films of Ge//2//2Se//7//8// minus //xBi//x with x equals 0, 2 and 10. Transient photoconductivity measurements have also been made on the same samples. Our results show that photosensitivity decreases as Bi concentration is increased from x equals 0 to x equals 2. However, at high concentration of Bi(x equals 10), photosensitivity again increases. Transient photoconductivity also shows a different behavior at low and high concentration of Bi. Results have been explained in terms of defect states produced due to Bi incorporation in Ge-Se system.