Group-IV monochalcogenides have recently shown great potential for their thermoelectric, ferroelectric, and other intriguing properties. The electrical properties of group-IV monochalcogenides exhibit a strong dependence on the chalcogen type. For example, GeTe exhibits high doping concentration, whereas S/Se-based chalcogenides are semiconductors with sizable bandgaps. Here, we investigate the electrical and thermoelectric properties of gamma-GeSe, a recently identified polymorph of GeSe. gamma-GeSe exhibits high electrical conductivity (~106 S/m) and a relatively low Seebeck coefficient (9.4 uV/K at room temperature) owing to its high p-doping level (5x1021 cm-3), which is in stark contrast to other known GeSe polymorphs. Elemental analysis and first-principles calculations confirm that the abundant formation of Ge vacancies leads to the high p-doping concentration. The magnetoresistance measurements also reveal weak-antilocalization because of spin-orbit coupling in the crystal. Our results demonstrate that gamma-GeSe is a unique polymorph in which the modified local bonding configuration leads to substantially different physical properties.
@article{arxiv.2304.06954,
title = {Electrical transport properties driven by unique bonding configuration in gamma-GeSe},
author = {Jeongsu Jang and Joonho Kim and Dongchul Sung and Jong Hyuk Kim and Joong-Eon Jung and Sol Lee and Jinsub Park and Chaewoon Lee and Heesun Bae and Seongil Im and Kibog Park and Young Jai Choi and Suklyun Hong and Kwanpyo Kim},
journal= {arXiv preprint arXiv:2304.06954},
year = {2023}
}