Wiedemann-franz law and electronic thermal conductivity in tall barrier superlattices

Zhixi Bian, R. Singh, M. Zebarjadi, Y. Ezzahri, A. Shakouri, W. Kim, S. L. Singer, A. Majumdar, J. H. Bahk, G. Zeng, J. E. Bowers, J. M.O. Zide, A. C. Gossard

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Low dimensional and nanostructured materials have shown great potential to achieve higher thermoelectric figure-of-merit ZT than their bulk counterparts. One reason is their reduced thermal conductivities. The total thermal conductivity is composed of lattice thermal conductivity and the contribution from charge carriers. We study the charge transport of tall barrier superlattices in the cross-plane direction and the electronic thermal conductivity. The periodic potential barriers modify the electronic band structure and thus the charge and heat transport in superlattices are quite different from the bulk materials. The band edge profile changes with carrier concentration and temperature due to the charge transfer between wells and barriers. This is taken into account by a self-consistent solution of the coupled SchrOdinger and Poisson equations. Finally, the electrical conductivity and electronic thermal conductivity are calculated using the Boltzmann transport equation in superlattice miniband regime. It is shown that the Lorenz number, i.e., the ratio of electronic thermal conductivity to electrical conductivity, in the superlattice cross-plane direction deviates substantially from the Wiedemann-Franz law of bulk materials.

Original languageEnglish
Title of host publicationMaterials Research Society Symposium Proceedings - Nanoscale Heat Transport - From Fundamentals to Devices
Pages14-19
Number of pages6
Publication statusPublished - 2007
EventNanoscale Heat Transport - From Fundamentals to Devices - 2007 MRS Spring Meeting - San Francisco, CA, United States
Duration: 2007 Apr 92007 Apr 13

Publication series

NameMaterials Research Society Symposium Proceedings
Volume1022
ISSN (Print)0272-9172

Other

OtherNanoscale Heat Transport - From Fundamentals to Devices - 2007 MRS Spring Meeting
CountryUnited States
CitySan Francisco, CA
Period07/4/907/4/13

All Science Journal Classification (ASJC) codes

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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    Bian, Z., Singh, R., Zebarjadi, M., Ezzahri, Y., Shakouri, A., Kim, W., Singer, S. L., Majumdar, A., Bahk, J. H., Zeng, G., Bowers, J. E., Zide, J. M. O., & Gossard, A. C. (2007). Wiedemann-franz law and electronic thermal conductivity in tall barrier superlattices. In Materials Research Society Symposium Proceedings - Nanoscale Heat Transport - From Fundamentals to Devices (pp. 14-19). (Materials Research Society Symposium Proceedings; Vol. 1022).