Improved thermoelectric performances of nanocrystalline Sb2Te3/Cr bilayers by reducing thermal conductivity in the grain boundaries and heterostructure interface.
- Resource Type
- Article
- Authors
- Mori, Ryotaro; Kurokawa, Takuya; Yamauchi, Kazuki; Tanaka, Saburo; Takashiri, Masayuki
- Source
- Vacuum. Mar2019, Vol. 161, p92-97. 6p.
- Subject
- *ANTIMONY telluride
*THERMAL conductivity
*CRYSTAL grain boundaries
*HETEROSTRUCTURES
*THERMOELECTRICITY
- Language
- ISSN
- 0042-207X
Abstract Nanocrystalline Sb 2 Te 3 /Cr bilayers with varying Cr layer thicknesses were prepared with the aim of improving thermoelectric performances. Prior to the deposition of Sb 2 Te 3 films, Cr layers with thicknesses ranging from 0 to 116 nm were deposited on glass substrates. The cross-sectional morphologies of the Sb 2 Te 3 /Cr bilayers showed that the Cr layer was tightly connected to both the Sb 2 Te 3 film and the substrate. The highest power factor of 9.1 μW/(cm·K2) was obtained for the single Sb 2 Te 3 film, while the lowest thermal conductivity (measured using the 3ω method) of 0.75 W/(m·K) was recorded for the Sb 2 Te 3 /Cr bilayer with a Cr layer thickness of 73 nm. This was attributed to combined phonon scattering on the grain boundaries of the nanocrystalline Sb 2 Te 3 films and the heterostructure interface between the Sb 2 Te 3 film and the Cr layer. The highest figure-of-merit (ZT = 0.28) was achieved for the Sb 2 Te 3 /Cr bilayer (Cr = 73 nm), while the single Sb 2 Te 3 film gave a ZT of 0.11. We conclude that the thermoelectric performance of the nanocrystalline Sb 2 Te 3 /Cr bilayers could be improved by introducing a Cr layer of an appropriate thickness. Highlights • Sb 2 Te 3 /Cr bilayers were deposited on a glass substrate by RF magnetron sputtering. • Effects of Cr layer thickness on the properties of the bilayers were investigated. • Crystal orientation and crystallite size were affected with the Cr layer thickness. • The lowest thermal conductivity of bilayer was 0.75 W/(m·K) at a Cr layer of 73 nm. • The highest ZT of 0.28 was led by phonon scattering in heterostructure interface. [ABSTRACT FROM AUTHOR]