Photoconductivity of Se90-xTe10Znx thin films

Photoconductive properties such as dark conductivity, steady state and transient photoconductivity of a-Se90-xTe10Znx thin films, prepared by thermal vacuum evaporation technique have been studied in temperature range 312-380 K. Analysis of data shows that activation energy of dark current is greater as compared to activation energy of photo current. Activation energy decreases with increase in Zn concentration which may be due to increase in defect density of states. Analysis of intensity dependent photoconductivity shows that bimolecular recombination is predominant. Photosensitivity is found to be maximum for Se88Te10Zn2 composition after that it decreases with increase in Zn concentration. Carrier lifetime decreases with increase in Zn concentration which also confirms that density of defect states increases. Transient photoconductivity shows that the carrier lifetime decreases with increase in Zn concentration. This decrease is due to transition trapping process.