Establishing phase diagram for the band engineering in p-type PbTe/SnTe from elementary electronic structure understanding

TL;DR

This paper develops a phase diagram for band engineering in p-type PbTe/SnTe based on an s-p bonding model, linking dopant s orbital energy levels to band tuning, enabling better dopant selection and understanding of thermoelectric properties.

Contribution

It introduces a phase diagram derived from an elementary electronic structure model that explains and predicts doping effects in PbTe/SnTe thermoelectric materials.

Findings

Band tuning effects are mainly governed by dopant s orbital energy levels.

The phase diagram explains existing experimental observations.

The method allows prediction of effective dopants from the periodic table.

Abstract

Band engineering is an important mechanism to increase the thermopower of thermoelectric materials by reconstructing the band structure near Fermi level. PbTe and SnTe are the most representative systems in which band engineering were achieved by various dopants. Starting with the elementary understanding of the band structures, we established the phase diagram for the band engineering in p-type PbTe/SnTe by constructing an s-p bonding model. We show that the effects of band tuning are mainly determined by an inherent parameter of doping element: the s orbital energy level. With the phase diagram, all the related experimental observations can be consistently explained, moreover, undiscovered effective dopants become foreseeable. Our study discovers an applicable criteria to pick up proper dopants from the periodic table directly, and the analytical method can be adopted to more thermoelectric materials.