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

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 CsBi₄Te₆ (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.

By high-resolution angle-resolved photoemission spectroscopy, itinerant carriers in CsBi₄Te₆ are revealed. CsBi₄Te₆ is a typical anisotropic narrow-gap semiconductor which is a practical candidate for low-temperature thermoelectric and superconducting applications. It is reasonable to believe that the newly discovered features of carriers in narrow-gap semiconductors are promising for designing optimal thermoelectric materials and superconductors.

http://ift.tt/2BpmZwe