Thermoelectric performance of Si{sub 0.8}Ge{sub 0.2}/Si heterostructures synthesized by MBE and sputtering
- Hi-Z Technology (??)
- Lawrence Livermore National Laboratory (United States)
- Naval Research Laboratory (United States)
- University of California, Los Angeles (United States)
The electronic properties of bulk materials are altered when they are incorporated into quantum wells. These wells may or may not impart beneficial electronic properties to an ensemble of such interfaces. Two-dimensional quantum wells (2D QWS) have been synthesized by alternating layers of Si and Si{sub 0.8}Ge{sub 0.2}. Such nanostructures are being investigated as a candidate thermoelectric material for high figures of merit ({ital Z}). The predicted enhancement is attributed to the confined motion of charge carriers in the 2D QW and can be translated into a large increase in conversion efficiency. This combination of materials is of interest since Si{sub 0.8}Ge{sub 0.2} is the preferred thermoelectric material for high temperature applications. Other heterostructures are also being investigated. Two techniques have been used to prepare these multilayer Si/Si{sub 0.8}Ge{sub 0.2} films, high-rate dual-magnetron sputtering and molecular beam epitaxy (MBE). Films have been deposited on single-crystal silicon and sapphire substrates. Substrate heating was used as a means of controlling film structure and electronic properties. Both types of films have been characterized with transmission electron microscopy (TEM) and selected area transmission electron diffraction. The thermoelectric properties of these films have also been determined over a broad range of temperature, extending from the boiling point of liquid helium to 1200 K. The performance of the MBE and sputtered films have been systematically compared. Efforts have been made to correct the electronic measurements of all thin films for the effects of their respective substrates. Preliminary thermoelectric measurements of these multilayer structures, especially those produced with MBE, lead us to believe that significant gains in the thermoelectric figure of merit ({ital Z}) may be possible with this approach. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 87097
- Report Number(s):
- CONF-940830-; ISSN 0094-243X; TRN: 95:017391
- Journal Information:
- AIP Conference Proceedings, Vol. 316, Issue 1; Conference: 13. international conference on thermoelectrics, Kansas City, MO (United States), 30 Aug - 1 Sep 1994; Other Information: PBD: 10 Aug 1994
- Country of Publication:
- United States
- Language:
- English
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