| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Thin Films | Thursday Sessions |
| Session TF-ThM |
| Session: | Graphene |
| Presenter: | Jun Nakamura, The University of Electro-Communications (UEC-Tokyo), Tokyo, Japan |
| Authors: | J. Nakamura, The University of Electro-Communications (UEC-Tokyo), Tokyo, Japan Y. Yokomizo, The University of Electro-Communications (UEC-Tokyo) and JST-CREST |
| Correspondent: | Click to Email |
The thermoelectric conversion has been of interest for many researchers since Hicks and Dresselhaus showed that the introduction of low-dimensional structures such as quantum well structures would significantly enhance the dimensionless figure of merit [1]. Graphene is a two-dimensional, mono-layer material having honeycomb lattice of carbon atoms [2,3]. It has been suggested that the graphene-based device can be a novel thermoelectric material because of its potential giant Seebeck coeffcient larger than 30 Mv/K [4]. On the other hand, graphene nanoribbon (GNR) is a one-dimensional (1D) material, a strip of graphene, which has also been investigated theoretically as thermoelectric materials. A molecular dynamics study has shown that a high figure of merit can be obtained for the zigzag GNR (ZGNR) [5]. This result implies that the introduction of 1D structural modulation makes graphene into novel thermoelectric materials. We hereby propose, in this study, superlattice models consisting of ZGNR and zigzag BN nanoribbon (ZBNNR) [6,7]. We have investigated the Seebeck coefficents of ZGNR/BNNRs within the Boltzmann transport theory. It has been shown that a ZGNR/ZBNNR marks up to 20 times larger in the Seebeck coefficient than graphene. The Seebeck coefficients of the superlattices increase with decreasing width of the constituent ZGNR. It has been revealed that the giant Seebeck coefficients of the superlattices stem from the so-called pudding mold band with a finite energy gap.
[1] L.D. Hicks and M.S. Dresselhaus, Phys. Rev. B 47, 12727 (1993).
[2] K. Saito, J. Nakamura, and A. Natori, Phys. Rev. B 76, 115409 (2007).
[3] E.Watanabe, S. Yamaguchi, J. Nakamura and A. Natori, Phys. Rev. B 80, 085404 (2009).
[4] D. Dragoman and M. Dragoman, Appl. Phys. Lett. 91, 203116 (2007).
[5] H. Zheng et al., Appl. Phys. Lett. 100, 093104 (2012).
[6] J. Nakamura, T. Nitta, and A. Natori, Phys. Rev. B 72, 205429 (2005).
[7] Y. Yokomizo and J. Nakamura, Appl. Phys. Lett. 103, 113901 (2013).