<link rel="File-List" href="file:///C:%5CDOCUME%7E1%5Ccharu%5CLOCALS%7E1%5CTemp%5Cmsohtml1%5C01%5Cclip_filelist.xml"> Steady state photoconductivity in a-Se₈₀_-xTe₂₀Ge_x thin films

Abstract

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The steady state photoconductivity of vacuum evaporated thin films of amorphous Se₈₀_-xTe₂₀Ge_x (x = 5, 10, 15 and 20) has been investigated. The measurements of temperature dependence of dark conductivity (σ_d) and photoconductivity (σ_ph) show that the conduction is through a thermally activated process in both the cases. The activation energy decreases with the increase in light intensity. This indicates the shift of Fermi level with intensity. 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. The photosensitivity (σ_ph/σ_d) increases with the increase of Ge concentration which indicates that the density of defect states decreases with the increase of Ge in a-Se₈₀_-xTe₂₀Ge_x. This is consistent with the conclusions reported in the literature by dielectric loss measurements.