Effect of Ag additive on the photoconductive properties of (Se₈₀Te₂₀)_100−xAg_x (1 ≤ x ≤ 4) thin films

Semiconductors Laboratory, Department of Physics, Guru Nanak Dev University, Amritsar 143005, Punjab, India

^a e-mail: digvijay_apd@yahoo.com
^b e-mail: rthangaraj@rediffmail.com

Received: 27 March 2011
Revised: 25 April 2011
Accepted: 3 May 2011
Published online: 18 August 2011

Abstract

Thin films of a (Se₈₀Te₂₀)_100−x Ag_x (1 ≤ x ≤ 4) were prepared by vacuum evaporation technique in a base pressure of 10⁻⁵ mbar onto well-cleaned glass substrates. The photoconductive measurements have been carried out on (Se₈₀Te₂₀)_100−xAg_x (1 ≤ x ≤ 4) thin films at different intensities 0–1200 lx in the temperature range 263–333 K. Dark conductivity (σ_d) and photoconductivity (σ_ph) increase but the activation energy decreases as Ag concentration increases in the present glass composition. The measurements of intensity dependence of photoconductivity show that the photoconductivity increases with intensity as a power law where the power is found to be between 0.5 and 1.0. The photosensitivity (σ_ph/σ_d) decreases with increase in Ag concentration. The results are explained on the basis of increase in the density of the localized states.