Electronic properties of co-doped nonstoichiometric germanium telluride. (April 2021)

• Record Type: Journal Article
• Authors: Ben-Ayoun, Dana; Gelbstein, Yaniv
• Is Part Of: Intermetallics. Volume 131(2021)
• Publication Date: 2021-04
• Subjects: Thermoelectric -- GeTe -- BiTe -- GEM; Intermetallic compounds -- Metallography -- Periodicals; Metallic glasses -- Periodicals; Composés intermétalliques -- Métallographie -- Périodiques; 669.94
• DOI: 10.1016/j.intermet.2021.107118
• Languages: English
• ISSNs: 0966-9795

Abstract

Abstract: GeTe-based alloys have been considered as p -type thermoelectric materials for decades. Yet the fact that they possess intrinsically high concentration of cation germanium vacancies have triggered the thermoelectric community in finding alternatives and strategies to optimize their efficiency. While most of the published studies mainly discuss the stoichiometric alloy, here we demonstrate the introduction of excess germanium/tellurium to the system. The nonstoichiometric alloy is doped with bismuth, acting as a donor simultaneously with an increased number of vacancies, enabling higher solubility of other impurities (iodine/indium). This strategy and the mechanisms involved, has been investigated and correlated to the microstructural characteristics. ZT of ~1.6 was obtained but more importantly, it opens the opportunity for a potential route for further thermoelectric enhancement. Highlights: GeTe -based alloys shows ZT enhancement throughout all temperature range, reaching a 60% improvement compared to pure GeTe. Achieved by electronic optimization using doping nonstoichiometric Gex Te1-x with both BiTe and cationic/anionic impurities. General effective media evaluation enables the assessment of other routes for further transport properties enhancement.