Direct observation of double valence-band extrema and anisotropic effective masses of the thermoelectric material SnSe

Abstract

Synchrotron-based angle-resolved photoemission spectroscopy is used to determine the electronic structure of layered SnSe, which was recently turned out to be a potential thermoelectric material. We observe that the top of the valence band consists of two nearly independent hole bands, whose tops differ by ~20 meV in energy, indicating the necessity of a multivalley model to describe the thermoelectric properties. The estimated effective masses are anisotropic, with in-plane values of 0.16-0.39 m${}_0$ and an out-of-plane value of 0.71 m${}_0$, where m${}_0$ is the rest electron mass. Information of the electronic structure is essential to further enhance the thermoelectric performance of hole-doped SnSe.

arXiv comment14 pages including 2 figures + 2 pages of supplementary data

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• Pressure-Induced Superconductivity in Layered Transition-metal Chalcogenides (Zr,Hf)GeTe${}_4$ Explored by Data-driven Approach
• Direct observation of multiple conduction-band minima in high-performance thermoelectric SnSe
• A plausible method of preparing the ideal p-n junction interface of a thermoelectric material by surface doping