Off-stoichiometric silver antimony telluride: An experimental study of transport properties with intrinsic and extrinsic doping

Journal Article · 20 March 2015 · AIP Advances

DOI: https://doi.org/10.1063/1.4916217 · OSTI ID:1174085

Nielsen, Michele D. ^[1]; Jaworski, Christopher M. ^[1]; Heremans, Joseph P.  ^[1]

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1. The Ohio State Univ., Columbus, OH (United States)

AgSbTe₂ is a thermoelectric semiconductor with an intrinsically low thermal conductivity and a valence band structure that is favorable to obtaining a high thermoelectric figure of merit zT. It also has a very small energy gap Eg ~ 7.6 ± 3 meV. As this gap is less than the thermal excitation energy at room temperature, near-intrinsic AgSbTe₂ is a two carrier system having both holes (concentration p) and electrons (n). Good thermoelectric performance requires heavy p-type doping (p > > n). This can be achieved with native defects or with extrinsic doping, e.g. with transition metal element. The use of defect doping is complicated by the fact that many of the ternary Ag-Sb-Te and pseudo-binary Sb₂Te₃-Ag₂Te phase diagrams are contradictory. This paper determines the compositional region most favorable to creating a single phase material. Through a combination of intrinsic and extrinsic doping, values of zT > 1 are achieved, though not on single-phased material. In addition, we show that thermal conductivity is not affected by defects, further demonstrating that the low lattice thermal conductivity of I-V-VI₂ materials is due to an intrinsic mechanism, insensitive to changes in defect structure.

• Research Organization: Energy Frontier Research Centers (EFRC), Washington, D.C. (United States). Revolutionary Materials for Solid State Energy Conversion (RMSSEC)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES)
• Grant/Contract Number: SC0001054
• OSTI ID: 1174085
• Alternate ID(s): OSTI ID: 1370336; OSTI ID: 1420647
• Journal Information: AIP Advances, Vol. 5, Issue 5; Related Information: RMSSEC partners with Michigan State University (lead); University of California, Los Angeles; University of Michigan; Northwestern University; Oak Ridge National Laboratory; Ohio State University; Wayne State University; ISSN 2158-3226
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English