AUTHOR=Ojha Swarupa , Chamuah Anil , Roy Madhab , Bhattacharya Sanjib 

TITLE=Comprehensive studies on the electrical transport of some chalcogenide semiconductors: frequency- and temperature-dependent AC conductivity

JOURNAL=Frontiers in Physics

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1151841

DOI=10.3389/fphy.2023.1151841

ISSN=2296-424X

ABSTRACT=<p>The AC conductivity of chalcogenide semiconductors doped with Ag<sub>2</sub>S was extensively studied, not only for applications in devices but also for academic interests. X-ray diffraction studies reveal the presence of GeS, Ag<sub>2</sub>S, Se<sub>5.1</sub>S<sub>1.9</sub>, Se<sub>2.57</sub>S<sub>5.43</sub>, Ag<sub>2</sub>Se, S<sub>3</sub>Se<sub>5</sub>, Se<sub>4.7</sub>S<sub>3.3</sub>, and Ag<sub>8</sub>S nanocrystallites. The characteristic vibration that appeared in the range 500–600 cm<sup>−1</sup> is due to the Ag–S bond, and the vibrations at 3,700 and 1600 cm<sup>−1</sup> can be assigned as the bending and stretching vibrations of the O–H bond, which may be formed due to the adsorption of H<sub>2</sub>O molecules on the Ag<sub>2</sub>S surface. DC electrical conductivity can be increased by optical phonon frequency, which may be involved in the enhancement of structural vibrations. At low temperatures, the “density of states” increases from 3.337 × 10<sup>19</sup> to 2.396 × 10<sup>21</sup> eV<sup>−1</sup> cm<sup>−3</sup>, and at high temperatures, it enhances from 3.417 × 10<sup>28</sup> to 1.1356 × 10<sup>31</sup> eV<sup>– 1</sup> cm<sup>−3</sup>. The correlated barrier hopping model explores the maximum barrier height for composition, x = 0.1 as 0.0292 eV. The modified non-overlapping small polaron tunnelling model reveals the polaron transfer activation energy for x = 0.2 as 0.09110 eV. The independence of the electrical relaxation process of the system on temperature and its dependence on composition were exhibited by the scaling of the conductivity spectra.</p>