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Author Madar, Naor ♦ Givon, Tom ♦ Mogilyansky, Dmitry ♦ Gelbstein, Yaniv
Source United States Department of Energy Office of Scientific and Technical Information
Content type Text
Language English
Subject Keyword CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY ♦ CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS ♦ BISMUTH TELLURIDES ♦ CONCENTRATION RATIO ♦ DOPED MATERIALS ♦ FERMI LEVEL ♦ GERMANIUM ALLOYS ♦ GERMANIUM TELLURIDES ♦ HOLES ♦ OPTIMIZATION ♦ SOLUBILITY ♦ TELLURIUM ALLOYS ♦ TEMPERATURE RANGE ♦ THERMOELECTRIC PROPERTIES
Abstract In an attempt to reduce our reliance on fossil fuels, associated with severe environmental effects, the current research is focused on the identification of the thermoelectric potential of p-type (GeTe){sub 1−x}(Bi{sub 2}Te{sub 3}){sub x} alloys, with x values of up to 20%. Higher solubility limit of Bi{sub 2}Te{sub 3} in GeTe, than previously reported, was identified around ∼9%, extending the doping potential of GeTe by the Bi{sub 2}Te{sub 3} donor dopant, for an effective compensation of the high inherent hole concentration of GeTe toward thermoelectrically optimal values. Around the solubility limit of 9%, an electronic optimization resulted in an impressive maximal thermoelectric figure of merit, ZT, of ∼1.55 at ∼410 °C, which is one of the highest ever reported for any p-type GeTe-rich alloys. Beyond the solubility limit, a Fermi Level Pinning effect of stabilizing the Seebeck coefficient was observed in the x = 12%–17% range, leading to stabilization of the maximal ZTs over an extended temperature range; an effect that was associated with the potential of the governed highly symmetric Ge{sub 8}Bi{sub 2}Te{sub 11} and Ge{sub 4}Bi{sub 2}Te{sub 7} phases to create high valence band degeneracy with several bands and multiple hole pockets on the Fermi surface. At this compositional range, co-doping with additional dopants, creating shallow impurity levels (in contrast to the deep lying level created by Bi{sub 2}Te{sub 3}), was suggested for further electronic optimization of the thermoelectric properties.
ISSN 00218979
Educational Use Research
Learning Resource Type Article
Publisher Date 2016-07-21
Publisher Place United States
Journal Journal of Applied Physics
Volume Number 120
Issue Number 3


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