High thermoelectric potential of Bi{sub 2}Te{sub 3} alloyed GeTe-rich phases

Journal Article · Thu Jul 21 04:00:00 EDT 2016 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4958973· OSTI ID:22597826

Madar, Naor; Givon, Tom; Mogilyansky, Dmitry; Gelbstein, Yaniv ^[1]

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1. Department of Materials Engineering, Ben-Gurion University of the Negev, Beer-Sheva (Israel)

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.

• OSTI ID: 22597826
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 3 Vol. 120; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BISMUTH TELLURIDES
CONCENTRATION RATIO
DOPED MATERIALS
FERMI LEVEL
GERMANIUM ALLOYS
GERMANIUM TELLURIDES
HOLES
OPTIMIZATION
SOLUBILITY
TELLURIUM ALLOYS
TEMPERATURE RANGE
THERMOELECTRIC PROPERTIES