Article abstract
Nature Materials 6, 129 - 134 (2007)
Published online: 21 January 2007 | doi:10.1038/nmat1821
Subject Categories: Electronic materials | Semiconductors
Giant thermoelectric Seebeck coefficient of a two-dimensional electron gas in SrTiO3
Hiromichi Ohta1,2,3, SungWng Kim4, Yoriko Mune1, Teruyasu Mizoguchi5, Kenji Nomura3, Shingo Ohta1, Takashi Nomura1, Yuki Nakanishi1, Yuichi Ikuhara5, Masahiro Hirano3, Hideo Hosono3,4 & Kunihito Koumoto1,2
Abstract
Enhancement of the Seebeck coefficient (S ) without reducing the electrical conductivity (
) is essential to realize practical thermoelectric materials exhibiting a dimensionless figure of merit (ZT=S2
T
-1) exceeding 2, where T is the absolute temperature and is the thermal conductivity. Here, we demonstrate that a high-density two-dimensional electron gas (2DEG) confined within a unit cell layer thickness in SrTiO3 yields unusually large |S|, approximately five times larger than that of SrTiO3 bulks, while maintaining a high 2DEG. In the best case, we observe |S|=850 
V K-1 and 2DEG=1.4
103 S cm-1. In addition, by using the of bulk single-crystal SrTiO3 at room temperature, we estimate ZT
2.4 for the 2DEG, corresponding to ZT0.24 for a complete device having the 2DEG as the active region. The present approach using a 2DEG provides a new route to realize practical thermoelectric materials without the use of toxic heavy elements.
- Nagoya University, Graduate School of Engineering, Furo-cho, Chikusa, Nagoya 464-8603, Japan
- CREST, JST, 4-1-8 Honcho, Kawaguchi 332-0012, Japan
- ERATO-SORST, JST, in Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
- Frontier Collaborative Research Center, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama 226-8503, Japan
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo, Tokyo 113-8656, Japan
Correspondence to: Hiromichi Ohta1,2,3 e-mail: h-ohta@apchem.nagoya-u.ac.jp
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