Evidence for Itinerant Carriers in an Anisotropic Narrow-Gap Semiconductor by Angle-Resolved Photoemission Spectroscopy

Sailong Ju; Wei Bai; Liming Wu; Hua Lin; Chong Xiao; Shengtao Cui; Zhou Li; Shuai Kong; Yi Liu; Dayong Liu; Guobin Zhang; Zhe Sun; Yi Xie

doi:10.1002/adma.201704733

Evidence for Itinerant Carriers in an Anisotropic Narrow-Gap Semiconductor by Angle-Resolved Photoemission Spectroscopy

Adv Mater. 2018 Jan;30(2). doi: 10.1002/adma.201704733. Epub 2017 Nov 27.

Authors

Sailong Ju¹, Wei Bai², Liming Wu³, Hua Lin³, Chong Xiao², Shengtao Cui¹, Zhou Li², Shuai Kong¹, Yi Liu¹, Dayong Liu⁴, Guobin Zhang¹, Zhe Sun¹, Yi Xie²

Affiliations

¹ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui, 230029, P. R. China.
² Hefei National Laboratory for Physical Sciences at the Microscale, iCHEM, University of Science and Technology of China, Hefei, Anhui, 230026, P. R. China.
³ Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, P. R. China.
⁴ Key Laboratory of Materials Physics, Institute of Solid State Physics, Chinese Academy of Sciences, P. O. Box 1129, Hefei, Anhui, 230031, P. R. China.

PMID: 29178538
DOI: 10.1002/adma.201704733

Abstract

The ability to accurately determine the electronic structure of solids has become a key prerequisite for modern functional materials. For example, the precise determination of the electronic structure helps to balance the three thermoelectric parameters, which is the biggest challenge to design high-performance thermoelectric materials. Herein, by high-resolution, angle-resolved photoemission spectroscopy (ARPES), the itinerant carriers in CsBi₄ Te₆ (CBT) are revealed for the first time. CBT is a typical anisotropic, narrow-gap semiconductor used as a practical candidate for low-temperature thermoelectric applications, and p-doped CBT series show superconductivity at relatively low carrier concentrations. The ARPES results show a significantly larger bandwidth near the Fermi surface than calculations, which means the carriers transport anisotropically and itinerantly in CBT. It is reasonable to believe that these newly discovered features of carriers in narrow-gap semiconductors are promising for designing optimal thermoelectric materials and superconductors.

Keywords: CsBi4Te6; angle-resolved photoemission spectroscopy; itinerant carriers; narrow-gap semiconductors.