ELECTRICAL AND PHOTOELECTRICAL PROPERTIES OF A-Ge20Te80-xBix (x = 0, 1.5, 2.5, 5.0) THIN FILMS

Abstract

Bulk samples of Te-rich Ge20Te80-xBix (x = 0, 1.5, 2.5, 5.0) glassy alloys are prepared by melt quenching technique. The thin films of the bulk samples are deposited by using vacuum evaporation technique for their electrical and photoelectrical measurements. Keithley 6487 picoammeter has been used to study the electrical and photoelectrical characteristics of Ge20Te80-XBix thin films kept in vacuum. Temperature dependent dark and photoconductivity is studied in the temperature range 300-360 K and voltage V = 80V. Photoconductivity with intensity at room temperature follows a power law where power γ lies near to 0.5, suggesting that the recombination is bimolecular in nature. The density of defect states and photosensitivity are found to follow an opposite trend with each other. The differential life time is determined from the rise and decay of photocurrent w.r.t. time. The dispersion parameter and localized state distribution parameter are estimated from decay curves and reported for the studied composition.