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

¹ Department of Physics, Harcourt Butler Technological Institute, Kanpur – 208 002, India
² Department of Physics, Christ Church College, Kanpur – 208 001, India

Corresponding author: dr_ashok_kumar@yahoo.com

Received: 16 February 2006
Revised: 5 April 2006
Accepted: 4 May 2006
Published online: 2 September 2006

Abstract

The present paper reports the measurements on space charge limited conduction in amorphous thin films of Ge₂₀SeAg_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 ~ 10⁴ V/cm), the current becomes superohmic. At high fields (10⁴ 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 Ge₂₀Se₈₀ alloy, density of localized states first increases till 10 at% of Ag and then decreases.