Electrical Transport Properties Driven by Unique Bonding Configuration in γ-GeSe.

Jang, Jeongsu; Kim, Joonho; Sung, Dongchul; Kim, Jong Hyuk; Jung, Joong-Eon; Lee, Sol; Park, Jinsub; Lee, Chaewoon et al. · Nano Lett · 2023

basic_science · Level V

Where this comes from

Abstract

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 γ-GeSe, a recently identified polymorph of GeSe. γ-GeSe exhibits high electrical conductivity (∼10<sup>6</sup> S/m) and a relatively low Seebeck coefficient (9.4 μV/K at room temperature) owing to its high p-doping level (5 × 10<sup>21</sup> cm<sup>-3</sup>), 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 γ-GeSe is a unique polymorph in which the modified local bonding configuration leads to substantially different physical properties.