Giant thermoelectric Seebeck coefficient of a two-dimensional electron gas in SrTiO3.
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.
Ohta
Hiromichi
H
Nagoya University, Graduate School of Engineering, Furo-cho, Chikusa, Nagoya 464-8603, Japan. h-ohta@apchem.nagoya-u.ac.jp
Kim
Sungwng
S
Mune
Yoriko
Y
Mizoguchi
Teruyasu
T
Nomura
Kenji
K
Ohta
Shingo
S
Nomura
Takashi
T
Nakanishi
Yuki
Y
Ikuhara
Yuichi
Y
Hirano
Masahiro
M
Hosono
Hideo
H
Koumoto
Kunihito
K