Photoconductivity studies on bulk As-Te-In glasses

Abstract

Photocurrent measurements have been undertaken on bulk As₄₀Te_60-xIn_x glasses of different compositions. It has been found that the photocurrent increases with illumination, which can probably be understood on the basis of the large dielectric constant of these materials and also due to the presence of a larger number of positive defect states. Further, the composition dependence of the conductivity activation energy and the photosensitivity exhibit a maximum at x=12.5(〈r〉=2.65) and a minimum at x=15(〈r〉=2.70). Earlier investigations on As-Te-In glasses, such as high-pressure resistivity behavior, electrical switching, etc., have identified the compositions x=12.5 and x=15 as the rigidity percolation threshold (RPT) and the chemical threshold (CT) respectively. Based on this, the maximum and the minimum seen in activation energy and photosensitivity of As₄₀Te_60-xIn_x glasses at x=12.5 and x=15 can be attributed to RPT and CT respectively.