Transient photoconductivity in a-(Se80Te20)100 xAgx(0rxr4) thin films

Bulk material of (Se₈₀Te₂₀)_100?xAg_x (0≤x≤4) system was prepared by using a conventional melt quenching technique. Thin films of a-(Se₈₀Te₂₀)_100?xAg_x (0≤x≤4) were deposited by the vacuum evaporation technique at a base pressure of 10^?4 mbar onto well-cleaned glass substrates. Temperature dependence of electrical conductivity in the temperature range of 263–333 K has been studied. There is increase in the value of conductivity with increase in temperature as well as with Ag content. The measurements of intensity dependence of photoconductivity show that the photoconductivity increases with intensity as a power law where the power is found to be between 0.5 and 1.0, representing the continuous distribution of traps. Rise and decay of photocurrent with time at room temperature at different light intensities for (Se₈₀Te₂₀)₉₈Ag₂ thin film samples have also been reported. The results have been explained on the basis of the Dember voltage and interaction between photoexcited holes and the trapped electrons on the surface.