Abstract
SnSe is a semiconductor with an indirect band gap energy of Eg =0.829 eV at 300 K with orthorhombic Pnma phase, while it shows direct band gap of Eg = 0.464 eV with Cmcm structure phase at high temperature. It exhibits two dimensional (2D) layered structure with strong Sn-Se bonding along b-c plane and weaker bonding along a axis direction, resulting in a strong anisotropic transport properties. Zhao et al. reported that high thermoelectric power factor and low thermal conductivity at high temperature make SnSe as a very good p-type thermoelectric material; ZT values along b and c axes are up to 2.6 and 2.3 at 923 K, respectively. First-principles calculations predicted good thermoelectric performances in both n- and p-type SnSe’s and better n-type thermoelectric properties than p-type SnSe. J. Yang et al. predicted ZT~3.1 in n-type SnSe. In this talk I will present about our recent achievement of ZT=2.2 in Bi-doped n-type SnSe single crystals.
 
RESUME
I. History
- Mar. 2000- present;  Professor, Dept of Physics, Univ of Ulsan, Korea
- Jan. 1998-Feb. 2000: post-doctral fellow, Dept of Physics, Northwestern Univ
- Sep. 1991-Dec. 1997: Ph. D., Dept of Physics, Northwestern Univ, USA
- Mar.1987-Feb. 1989: MS, Dept of Physics, Pusan National Univ, Korea
- Mar.1983-Feb. 1987: BS, Dept of Physics, Pusan National Univ, Korea
II. Research Fields
- Thermoelectric materials for Seebeck Power generator and Peltier cooler
- Magnetic thin film: MBE growth and physical properties
III. Recent Publications
 - A, T, Duong et al. “Achieving ZT=2.2 with Bi-doped n-type SnSe single crystals”, Nature Communications 7, 13713 (2016).
- W. Feng et al. “Snthetic hybrid Co2FeGe/Ge(Mn) superlattice for spintronics applications”, Applied Physics Letters 109, 172401 (2016).