Asymmetric electronic band alignment and potentially enhanced thermoelectric properties in phase-separated Mg2X (X = Si,Ge,Sn) alloys
Abstract
The Mg2X (X = Si, Ge, Sn) based alloy is an eco-friendly thermoelectric material for mid-temperature applications. The Mg2Si1−xSnx and Mg2Ge1−xSnx alloys can be phase-separated into Si(Ge)- and Sn-rich phases during material synthesis, leading to a nanocomposite with locally varying electronic band structures. First-principles calculations reveal that the valence band offset is eight-times larger than the conduction band offset at the interface between Si- and Sn-rich phases for x = 0.6, showing type I and asymmetric band alignment (0.092 vs 0.013 eV). Using the Boltzmann transport theory and thermionic emission calculations, we show that the large valence band energy discontinuity could allow for energy filtering effects to take place that can potentially increase the power factor substantially in the p-type material system if designed appropriately.
Article Details
Journal Info
Journal of Applied Physics
American Institute of Physics
Authors (11)
Byungki Ryu
Energy Conversion Research Center, Electrical Materials Research Division, Korea Electrotechnology Research Institute (KERI) 1 , Changwon 51543,
Samuel Foster
School of Engineering, University of Warwick 3 , Coventry CV4 7AL,
Eun-Ae Choi
Extreme Materials Research Institute, Korea Institute of Materials Science 5 , Changwon, Gyeongnam 51508,
Sungjin Park
Jaywan Chung
Energy Conversion Research Center, Electrical Materials Research Division, Korea Electrotechnology Research Institute (KERI) 1 , Changwon 51543,
Johannes de Boor
Pawel Ziolkowski
Eckhard Müller
Seung Zeon Han
Extreme Materials Research Institute, Korea Institute of Materials Science 5 , Changwon, Gyeongnam 51508,
SuDong Park
Energy Conversion Research Center, Electrical Materials Research Division, Korea Electrotechnology Research Institute (KERI) 1 , Changwon 51543,
Neophytos Neophytou
School of Engineering, University of Warwick 3 , Coventry CV4 7AL,