The effect of the Sb content on the physical properties of amorphous Se0.75Ge0.25-y thin films

The effect of the addition of varying amounts of antimony in concentrations from 0.01 to 0.20 at% to Se0.75Ge0.25-y glass on its de conductivity is an alysed. The electrical conductivity of amorphous thin films of vacuum evapo rated Se0.75Ge0.25-ySby were determined during and after light exposure and at different temperatures. The time dependence of the electrical conductiv ity measured in darkness or when exposed to light at about room temperature has been studied for amorphous Se0.75Ge0.25-ySby (y = 0.01, 0.05, 0.10, 0. 15, 0.18 and 0.20) thin films of different compositions and different thick nesses. The conduction activation energy Delta E and the pre-exponential fa ctor sigma(o) (0, T) which appear in the de conductivities are found to dec rease with increasing Sb content. The mean value of the threshold voltage, was measured either in darkness, (V) over bar(th), and after exposure of li ght (V) over bar(th), for different compositions and temperatures. The pron ounced glass-forming tendencies of alloys of Se and Ge with Sb were discuss ed topologically in terms of the chemical bonds expected to be present in t hese materials. These chemical bonds have been used to estimate the cohesiv e energies (CE) of the glasses. (C) 1999 Elsevier Science Ltd. All rights r eserved.