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Title: Energetics and diffusion of gold in bismuth telluride-based thermoelectric compounds

We investigate experimentally and theoretically the long-term chemical and morphological stability of Au contacts on Bi{sub 2}Te{sub 3}-based materials. Electron microscopy and energy dispersive spectroscopy experiments show that thermal annealing severely degrades the integrity of micron-thick Au films on n-type Bi{sub 2}Te{sub 3}, eventually leading to their complete dissolution. To explain this result, we have used density functional theory to calculate defect formation energies and diffusion barriers of Au within Bi{sub 2}Te{sub 3}. We identify an interstitial binding site consistent with previous reports of (rapid) anisotropic diffusion of Au in Bi{sub 2}Te{sub 3}. We find, however, that substitutional Au has lower formation energies. We suggest that these substitutional defects may be active in our experiments and account for the relatively long time scale of the contact degradation.
Authors:
; ; ;  [1]
  1. Sandia National Laboratories, Livermore, California 94550 (United States)
Publication Date:
OSTI Identifier:
22278065
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 6; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANISOTROPY; ANNEALING; BISMUTH; BISMUTH TELLURIDES; DENSITY FUNCTIONAL METHOD; DIFFUSION BARRIERS; ELECTRON MICROSCOPY; FORMATION HEAT; GOLD; PHASE STABILITY; THIN FILMS; X-RAY SPECTROSCOPY