Electronic and thermal transport in GeTe: A versatile base for thermoelectric materials

Journal Article · Wed Aug 28 00:00:00 EDT 2013 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4819222· OSTI ID:22218099

Levin, E. M. ^[1]; Besser, M. F.; Hanus, R. ^[1]

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1. Division of Materials Sciences and Engineering, Ames Laboratory U.S. DOE, Iowa State University, Ames, Iowa 50011 (United States)

GeTe is a narrow-band gap semiconductor, where Ge vacancies generate free charge carriers, holes, forming a self-dopant degenerate system with p-type conductivity, and serves as a base for high-performance multicomponent thermoelectric materials. There is a significant discrepancy between the electronic and thermal transport data for GeTe-based materials reported in the literature, which obscures the baseline knowledge and prevents a clear understanding of the effect of alloying GeTe with various elements. A comprehensive study including XRD, SEM, EDS, Seebeck coefficient, electrical resistivity, thermal conductivity, and {sup 125}Te NMR of several GeTe samples was conducted. Similar Seebeck coefficient and electrical resistivity are observed for all GeTe samples used showing that the concentration of Ge vacancies generating charge carriers is constant along the ingot. Very short {sup 125}Te NMR spin-relaxation time agrees well with high carrier concentration obtained from the Hall effect measurements. Our data show that at ∼700 K, GeTe has a very large power factor, 42 μWcm{sup −1}K{sup −2}, much larger than that of any high efficiency thermoelectric telluride at these temperatures. Electronic and thermal properties of GeTe are compared to PbTe, another well-known thermoelectric material, where free charge carriers, holes or electrons, are generated by vacancies on Pb or Te sites, respectively. Discrepancy in the data for GeTe reported in literature can be attributed to the variation in the Ge:Te ratio of solidified samples as well as to different conditions of measurements.

• OSTI ID: 22218099
• Journal Information: Journal of Applied Physics, Vol. 114, Issue 8; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
CARRIER DENSITY
CHARGE CARRIERS
CHEMICAL ANALYSIS
ELECTRIC CONDUCTIVITY
GERMANIUM TELLURIDES
HALL EFFECT
LEAD TELLURIDES
NUCLEAR MAGNETIC RESONANCE
POWER FACTOR
RELAXATION TIME
SCANNING ELECTRON MICROSCOPY
SEMICONDUCTOR MATERIALS
TELLURIUM 125
THERMAL CONDUCTIVITY
THERMOELECTRIC MATERIALS
VACANCIES
X-RAY DIFFRACTION