A study on electrical (dc/ac) conductivity and dielectric characteristics of quaternary Ge50In4Ga13Se33 chalcogenide thin films

Abstract

Thermally evaporated Ge50In4Ga13Se33 thin films of different thicknesses (126–745 nm) within the frequency range (100 Hz–1 MHz) and in the temperature range (293–413 K) had been studied to investigate the dc electrical conductivity σdc, temperature and frequency dependence of ac conductivity σac(ω) and dielectric parameters. It turned out that dc electrical conductivity σdc is thermally activated over the entire temperature range and the value of ΔEσ was independent of the film thickness and nearly equal the half value of optical energy gap Eopt g . The ac conductivity σac(ω) was found to be temperature and frequency dependent. Values of the ac activation energy ΔEσ(ω) were calculated and decreased with the applied frequency. The ωs law was found to be applicable with the results and the frequency exponent s has a positive value ≤1. The obtained values of s were decreased with temperature and interpreted in terms of the correlated barrier hopping (CBH) model. Values of the maximum height of the barrier WM and the density of localized states at the Fermi level N(EF) were calculated. The real ε′ (ω) and imaginary ε′′(ω) parts of dielectric constant were studied as a function of frequency and temperature.