Effective n-type doping of Mg3Sb2 with group-3 elements

Abstract

The recent discovery of high thermoelectric performance in Mg3Sb2 has been critically enabled by the success in n-type doping of this material, which is achieved under Mg-rich growth conditions, typically with chalcogens (Se and Te) as extrinsic dopants. Using first-principles defect calculations, we previously predicted that higher electron concentrations (∼1020cm−3) can be achieved in Mg3Sb2 by doping with La instead of Se or Te [P. Gorai et al., J. Mater. Chem. A 6, 13806 (2018)]. Subsequent experiments [K. Imasato et al., J. Mater. Chem. A 6, 19941 (2018)] showed that free electron concentration in La-doped Mg3Sb2−xBix indeed exceeds those in the Te-doped material. Herein, we further investigate n-type doping of Mg3Sb2 and predict that, in addition to La, other group-3 elements (Sc and Y) are also effective as n-type dopants; Y is as good as La while Sc slightly less. Overall, we find that doping with any group-3 elements should lead to higher free electron concentrations than doping with chalcogens.