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

• Published in: Applied physics letters 2022-01, Vol.120 (2)
• Main Authors: Zhou, Xiao-Li, Lv, Yang-Yang, Zhang, Hang-Fei, Zhang, Yong, Zhang, Jinglei, Zhou, Jian, Yao, Shu-Hua, Chen, Y. B., Chen, Yan-Feng
• Format: Article
• Language: English
• Subjects: Applied physics; Cerium; Crystal growth; Crystals; Current carriers; Doping; Electrical resistivity; Electrons; Halogens; Homojunctions; Single crystals; Thermoelectricity
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/5.0078990

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.