Impact of the Topological Surface State on the Thermoelectric Transport in Sb$_2$Te$_3$ Thin Films

TL;DR

This study investigates how topological surface states influence the thermoelectric properties of Sb$_2$Te$_3$ thin films, combining theoretical calculations with experimental measurements to identify the surface state's role in transport behavior.

Contribution

It provides a detailed analysis of the surface state's impact on thermoelectric transport in Sb$_2$Te$_3$ films, integrating ab initio calculations with experimental validation.

Findings

Surface states significantly affect thermoelectric properties.

A crossover between surface-dominant and bulk transport regimes was observed.

Theoretical results align with experimental measurements.

Abstract

Ab initio electronic structure calculations based on density functional theory and tight-binding methods for the thermoelectric properties of p-type Sb$_2$Te$_3$ films are presented. The thickness-dependent electrical conductivity and the ther- mopower are computed in the diffusive limit of transport based on the Boltzmann equation. Contributions of the bulk and the surface to the transport coefficients are separated which enables to identify a clear impact of the topological surface state on the thermoelectric properties. By tuning the charge carrier concentration, a crossover between a surface-state-dominant and a Fuchs-Sondheimer transport regime is achieved. The calculations are corroborated by thermoelectric transport measurements on Sb$_2$Te$_3$ films grown by atomic layer deposition.