Effect of Ag additive on the density of localized states in Se-Ge glassy alloy

Abstract

The present paper reports the measurements on space charge limited conduction in amorphous thin films of Ge 20 Se $_{80-x}$ Ag x ( x = 0, 10, 15, 20). I−V characteristics have been measured at various fixed temperatures. These characteristics show that, at low electric fields, an ohmic behaviour is observed. However, at high electric fields ( E ~ 10 4 V/cm), the current becomes superohmic. At high fields (10 4 V/cm), current could be fitted to the theory of space charge limited conduction (SCLC) in case of uniform distribution of localized states in the mobility gap of these materials. Using the theory of SCLC for the uniform distribution of the traps, the density of localized states near Fermi level is calculated. It is observed that, on addition of Ag in Ge 20 Se 80 alloy, density of localized states first increases till 10 at% of Ag and then decreases.