skip to main content

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

AgSbTe{sub 2} 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 AgSbTe{sub 2} 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 Sb{sub 2}Te{sub 3}-Ag{sub 2}Te 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. Additionally, we show that thermal conductivity is not affected by defects, further demonstrating that the low lattice thermal conductivity of I-V-VI{sub 2} materials is due to an intrinsic mechanism, insensitive to changes in defect structure.
Authors:
;  [1] ;  [1] ;  [2] ;  [2]
  1. Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
22488563
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Advances; Journal Volume: 5; Journal Issue: 5; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ANTIMONY TELLURIDES; DEFECTS; ELECTRONS; ENERGY GAP; EXCITATION; PHASE DIAGRAMS; SEMICONDUCTOR MATERIALS; SILVER; SILVER TELLURIDES; TEMPERATURE RANGE 0273-0400 K; THERMAL CONDUCTIVITY