Enhancement in figure-of-merit with superlattices structures for thin-film thermoelectric devices
Thin-film superlattice (SL) structures in thermoelectric materials are shown to be a promising approach to obtaining an enhanced figure-of-merit, ZT, compared to conventional, state-of-the-art bulk alloyed materials. In this paper the authors describe experimental results on Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures, relevant to thermoelectric cooling and power conversion, respectively. The short-period Bi{sub 2}Te{sub 3} and Si/Ge SL structures appear to indicate reduced thermal conductivities compared to alloys of these materials. From the observed behavior of thermal conductivity values in the Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} SL structures, a distinction is made where certain types of periodic structures may correspond to an ordered alloy rather than an SL, and therefore, do not offer a significant reduction in thermal conductivity values. The study also indicates that SL structures, with little or weak quantum-confinement, also offer an improvement in thermoelectric power factor over conventional alloys. They present power factor and electrical transport data in the plane of the SL interfaces to provide preliminary support for the arguments on reduced alloy scattering and impurity scattering in Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures. These results, though tentative due to the possible role of the substrate and the developmental nature of the 3-{omega} method used to determine thermal conductivity values, suggest that the short-period SL structures potentially offer factorial improvements in the three-dimensional figure-of-merit (ZT3D) compared to current state-of-the-art bulk alloys. An approach to a thin-film thermoelectric device called a Bipolarity-Assembled, Series-Inter-Connected Thin-Film Thermoelectric Device (BASIC-TFTD) is introduced to take advantage of these thin-film SL structures.
- Research Organization:
- Research Triangle Inst., Research Triangle Park, NC (US)
- Sponsoring Organization:
- US Department of the Navy, Office of Naval Research (ONR)
- OSTI ID:
- 20014242
- Resource Relation:
- Conference: 1997 Materials Research Society Spring Meeting, San Francisco, CA (US), 03/31/1997--04/03/1997; Other Information: Single article reprints are available through University Microfilms Inc., 300 North Zeeb Road, Ann Arbor, Michigan 48106; PBD: 1997; Related Information: In: Thermoelectric materials -- New directions and approaches. Materials Research Society symposium proceedings, Volume 478, by Tritt, T.M.; Kanatzidis, M.G.; Lyon, H.B. Jr.; Mahan, G.D. [eds.], 359 pages.
- Country of Publication:
- United States
- Language:
- English
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