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Controlling compositional homogeneity and crystalline orientation in Bi <sub>0.8</sub> Sb <sub>0.2</sub> thermoelectric thin films [Control of composition and crystallinity in Bi<sub>0.8</sub>Sb<sub>0.2</sub> thermoelectric thin films] [electronic resource].

Published
Washington, D.C. : United States. National Nuclear Security Administration, 2015.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy
Physical Description
Article numbers 126,106 : digital, PDF file
Additional Creators
Sandia National Laboratories, United States. National Nuclear Security Administration, and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Controlling alloy composition, crystalline quality, and crystal orientation is necessary to achieve high thermoelectric performance in Bi1-xSbx thin films. These microstructural attributes are demonstrated in this letter via co-sputter deposition of Bi and Sb metals on Si/SiO2 substrates followed by ex-situ post anneals ranging from 200 – 300 °C in forming gas with rapid cooling to achieve orientation along the trigonal axis. We show with cross-sectional transmission electron microscopy and energy-dispersive X-ray spectrometry that 50 – 95% of the Sb segregates at the surface upon exposure to air during transfer. This then forms a nanocrystalline Sb2O3 layer upon annealing, leaving the bulk of the film primarily Bi metal which is a poor thermoelectric material. We demonstrate a SiN capping technique to eliminate Sb segregation and preserve a uniform composition throughout the thickness of the film. Given that the Bi1-xSbx solid solution melting point depends on the Sb content, the SiN cap allows one to carefully approach but not exceed the melting point during annealing. This leads to the strong orientation along the trigonal axis and high crystalline quality desired for thermoelectric applications.
Report Numbers
E 1.99:sand--2015-5236j
sand--2015-5236j
Subject(s)
Note
Published through SciTech Connect.
12/01/2015.
"sand--2015-5236j"
"594458"
APL Materials 3 12 ISSN 2166-532X AM
C. Rochford; D. L. Medlin; K. J. Erickson; M. P. Siegal.
Funding Information
AC04-94AL85000
View MARC record | catkey: 24056449