(Invited) Controlled Synthesis and Thermoelectric Properties of Tin Telluride-Based Topological Crystalline Insulator Nanowires

Abstract

Tin telluride (SnTe) and its related alloys have recently attracted significant interest in the thermoelectric community because of their great potential as environmental-friendly alternatives to the conventional lead telluride-based thermoelectric materials. Meanwhile, they have been demonstrated by condensed matter physicists to be a class of novel quantum materials named topological crystalline insulators (TCI's), which host topological states on their high symmetry crystal surfaces. The SnTe-based TCI's possess intriguing surface properties, including Dirac cones in their electronic band structure and Van-Hove singularities in the density of states. One-dimensional TCI nanowires with large surface-area-to-volume ratios and well-defined facets provide an excellent platform to enhance topological surface contributions to the thermoelectric properties. In this talk, I will present the controlled growth and thermoelectric studies of SnTe-based TCI nanowires. In particular, I will discuss how we control the facet, diameter, doping, and alloying in the vapor-liquid-solid growth of SnTe nanowires. Measurements of the Seebeck coefficient, and electrical and thermal conductivities were performed on the same single nanowires to accurately determine their thermoelectric figure of merit. I will discuss the enhancement of the Seebeck coefficient and suppression of thermal conductivity in connection with the topological states, doping, alloying, and nano-structuring.