Alternating-current conductivity and dielectric properties of Ge₂₅Sb_15-xBi_xS₆₀bulk and thin-film glasses

Abstract

The effect of the replacement of antimony atoms by bismuth atoms on the electrical properties of compounds of the melt-quenched and thermally evaporated Ge25Sb15-xBixS60 (x = 0, 5, 10 and 15) chalcogenide system are reported for the first time. The results for the alternating-current (ac) conductivity σac and the dielectric constant ϵ1 of some bulk and thin-film samples of the four different compositions are presented over the temperature range 134-373 K and the frequency range 0.1-100 kHz. The ac conductivity increases with increase in the Bi content and deposition rate and decreases with increase in the film thickness. Its frequency exponent s exhibits strong temperature dependence. Analysis of the results in the light of the correlated barrier-hopping model for ac conduction reveals that electronic conduction takes place by single-polaron and bipolaron hopping processes at high and low temperatures respectively. The effects of composition, temperature, deposition rate and film thickness on the dielectric constant and the loss factor are studied. The dielectric constant and the loss factor are found to increase with increase of the Bi content and the deposition rate, especially at high temperatures and low frequencies. It is also found that increase in the film thickness leads to increase of the dielectric constant. The values of the electrical conductivity of the thin-film samples are higher by over one order of magnitude than those of the corresponding bulk samples, a fact that can be attributed to the higher density of defect states in the former.

Study of the optical properties and frequency-dependent electrical modulus spectrum to the analysis of electric relaxation and conductivity effect in zinc oxide nanoparticles

“…Relaxation mechanisms are for the most part two sorts to be specific (i) quantum-mechanical tunneling (QMT) through the barrier and (ii) classical hopping over the barrier [74,75]. The QMT conduction of charge carriers through barriers separating localized mechanism is not applicable in this ZnO NPs sample because s is depending on temperature in this experiment [76]. Velayutham et al also observed the CBH in the ZnO NPs sample and they explain the differences between CBH and QMT in semiconducting ZnO nanosystems [77].…”

Electrical conductivity and optical absorption of (Ge2S3)1(Sb2Te3)1 amorphous thin films

“…The electrical conductivity of Ge-M-S (M = Bi or Sb) was the subject of many investigations [2][3][4][5][6][7]. Various mechanisms of conductivity in bulk and thin films of Ge x Sb 40−x Se 60 chalcogenides system have been suggested [3].…”

Dielectric Relaxation in CdxInSe9-x Chalcogenide Thin Films

“…Chalcogenide glasses have attracted researchers' interest because of their potential use in opto electronic and technological applications such as photo resists, image storage, and memory switching. AC conductivity and dielectric measurements have been reported for a wide variety of amorphous Chalcogenide semiconductors [1][2][3][4][5][6][7] in order to understand the mechanisms of conduction processes in these materials and the types of polarization. Chalcogenide glasses with low phonon energies and high refractive indices were found to be efficient host materials for fiber-optics amplifiers and infrared lasers when doped with rare earth ion [8].…”