Electronic structure and transport anisotropy of Bi2Te3 and Sb2Te3

TL;DR

This study uses ab initio methods to analyze how strain affects the electrical transport anisotropy of Bi2Te3 and Sb2Te3, revealing the impact of lattice modifications on thermoelectric properties.

Contribution

It provides new insights into the strain-dependent anisotropy of transport distribution in Bi2Te3 and Sb2Te3, including effects of doping and lattice structure.

Findings

Transport anisotropy overestimates experimental data for Bi2Te3.

In-plane lattice expansion increases anisotropy for p-doping.

Lattice expansion decreases anisotropy for n-doping.

Abstract

On the basis of detailed ab initio studies the influence of strain on the anisotropy of the transport distribution of the thermoelectrics Bi$_2$Te$_3$ and Sb$_2$Te$_3$ was investigated. Both tellurides were studied in their own, as well as in their co-partners lattice structure to gain insight to the electrical transport in epitaxial heterostructures composed of both materials. It is shown, that the anisotropy of the transport distribution overestimates the experimental findings for Bi$_2$Te$_3$, implying anisotropic scattering effects. An increase of the in-plane lattice constant leads to an enhancement of the transport anisotropy for $p$-doping, whereas the opposite occurs for $n$-doping. The recent findings and special features of the transport distribution are discussed in detail in relation to the topology of the band structures.