Giant thermoelectric Seebeck coefficient of a two-dimensional electron gas in SrTiO3

✍ Scribed by Ohta, Hiromichi; Kim, SungWng; Mune, Yoriko; Mizoguchi, Teruyasu; Nomura, Kenji; Ohta, Shingo; Nomura, Takashi; Nakanishi, Yuki; Ikuhara, Yuichi; Hirano, Masahiro

• Book ID: 109934104
• Publisher: Nature Publishing Group
• Year: 2007
• Tongue: English
• Weight: 410 KB
• Volume: 6
• Category: Article
• ISSN: 1476-1122
• DOI: 10.1038/nmat1821

✦ Synopsis

Enhancement of the Seebeck coefficient (S ) without reducing the electrical conductivity (sigma) is essential to realize practical thermoelectric materials exhibiting a dimensionless figure of merit (ZT=S2 x sigma x T x kappa-1) exceeding 2, where T is the absolute temperature and kappa is the thermal conductivity. Here, we demonstrate that a high-density two-dimensional electron gas (2DEG) confined within a unit cell layer thickness in SrTiO(3) yields unusually large |S|, approximately five times larger than that of SrTiO(3) bulks, while maintaining a high sigma2DEG. In the best case, we observe |S|=850 microV K-1 and sigma2DEG=1.4 x 10(3) S cm-1. In addition, by using the kappa of bulk single-crystal SrTiO(3) at room temperature, we estimate ZT approximately 2.4 for the 2DEG, corresponding to ZT approximately 0.24 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.