Observation of a power factor enhancement in MBE-grown Bi1-xSbx alloy thin films

Sunglae Cho*, Antonio DiVenere, George K. Wong, John B Ketterson, Jerry R. Meyer, Craig A. Hoffman

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review

6 Scopus citations

Abstract

Bulk Bi1-xSbx is a direct (indirect) gap semiconductor for 0.07<x<0.15(0.15<x<0.22) with a maximum bandgap of 14-20 meV at x≈0.12-0.15. Small bandgap Bi1-xSbx alloys have been used as the n-type thermoelement for coolers operating around 80 K. The optimum operating temperature strongly depends on the magnitude of the bandgap of the material. We have grown BiSb alloy thin films on CdTe(111)B over a wide range of Sb concentrations using molecular beam epitaxy and have observed a maximum bandgap of 40 meV at x = 0.09, which is larger than that observed in bulk alloys. Thermoelectric power (TEP) measurements showed that a maximum TEP value occurred in a thin film with x = 0.09. This thin-film TEP value was 16% larger than bulk at room temperature. The power factor (S2σ) results show that the BiSb alloy thin films peak at a significantly higher temperature (250 K) than previously reported for the bulk alloy (80 K), which is possibly due to the enhanced bandgap. This bandgap enhancement may be associated with strain effects. The results show significant promise for use of band-engineered materials in thermoelectric devices.

Original languageEnglish (US)
Pages188-191
Number of pages4
StatePublished - Dec 1 1997
EventProceedings of the 1997 16th International Conference on Thermoelectrics, ICT'97 - Dresden, Ger
Duration: Aug 26 1997Aug 29 1997

Other

OtherProceedings of the 1997 16th International Conference on Thermoelectrics, ICT'97
CityDresden, Ger
Period8/26/978/29/97

ASJC Scopus subject areas

  • Engineering(all)

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