Effect of Pb impurity on the localized states of Se–Ge glassy alloy

Space charge limited conduction (SCLC) is investigated in vacuum evaporated thin films of (Ge20Se80)1−xPbx (x = 0, 0.02, 0.04, 0.06). I–V characteristics have been measured at various fixed temperatures. At high fields (∼104 V cm−1), current could be fitted to the theory of space charge limited conduction in case of uniform distribution of localized states in the mobility gap of these materials. Using the above theory, the density of localized states near Fermi level is calculated. A reversal in density of localized states is obtained at 4 at.% of Pb.