Realization of adjustable electron concentration and its effect on electrical- and Seebeck-property of n-type SnSe crystals.

Manipulation of carrier types in SnSe crystals is quite advantageous to fabricate SnSe-based homojunction devices such as thermoelectric modules. However, tuning the n-type charge carrier at an optimal level of SnSe is quite challenging because of its natural p-type without intentional doping. Here, we report the realization of the n-type SnSe through halogens or Ce doping. Importantly, heavily electron doped SnSe single crystals (∼10¹⁹ cm⁻³) can be obtained by Ce-doping through the Bridgeman method. The electrical conductivity of as-grown SnSe crystals evolves from thermally activated behavior to the metallic one when the electron concentrations are increased from 10¹⁶ to 10¹⁹ cm⁻³. Remarkably, the power-factor and electronic quality factor of heavily electron Ce-doped SnSe crystals can reach 1.59 and 0.44 μW cm⁻¹ K⁻² at 300 K, respectively, which is one of the best thermoelectric n-type SnSe. This work suggests that Ce-doping through the Bridgeman method is an ideal route for further improving the thermoelectric property of n-type SnSe crystals. [ABSTRACT FROM AUTHOR]