Effect of film thickness and deposition rate on the AC electrical conductivity and dielectric properties of Sb_xS_1−x thin films

Physics Department, Faculty of Education, Ain Shams University, Roxy, Cairo, Egypt

Corresponding author: msaman@hotmail.com

Received: 16 October 2001
Revised: 17 October 2002
Accepted: 7 November 2002
Published online: 11 December 2002

Abstract

Measurements were carried out in the temperature range 293–453 K over the frequency range 100 Hz–100 kHz on the ac electrical properties of vacuum deposited Sb_xS_1−x thin films of different thicknesses prepared with different deposition rates. The obtained experimental data have been analyzed with reference to various theoretical models. The ac conductivity increases with frequency according to the relation σ_ac(ω) α ω^s. The analysis shows that the correlated barrier-hopping (CBH) model is the most appropriate mechanism for the ac conduction in these films. The value of the dielectric constant slightly changed for higher frequencies irrespective of temperature change, whereas its value increases at higher temperature with the decrease in frequency. The dielectric loss has been found to increase with increase in temperature and decrease in frequency. The deposition rate and film thickness have a remarkable effect on ac conductivity and dielectric properties. The maximum barrier height w_m is calculated from dielectric measurements according to Guintini et al. equation based on Elliott (CBH) model; which suggested the hopping of charge carriers over a potential barrier between charged defect states. The density of states was also calculated using Elliott model.