Acoustic Deformation Potentials of $n$-Type PbTe from First Principles

TL;DR

This study calculates the acoustic deformation potentials of PbTe's conduction band valleys from first principles, revealing that intravalley acoustic phonon scattering is weaker than previously believed, with implications for electronic transport modeling.

Contribution

It provides first-principles calculations of deformation potentials in PbTe using different functionals, highlighting the weaker intravalley scattering compared to experimental estimates.

Findings

Deformation potentials are similar across functionals when conduction band states are accurately represented.

Calculated deformation potentials for the L valleys are consistent with some experimental data.

Intravalley acoustic phonon scattering in PbTe is weaker than previously estimated from transport measurements.

Abstract

We calculate the uniaxial and dilatation acoustic deformation potentials, $\Xi^{\text{L}}_{u}$ and $\Xi^{\text{L}}_{d}$, of the conduction band L valleys of PbTe from first principles, using the local density approximation (LDA) and hybrid functional (HSE03) exchange-correlation functionals. We find that the choice of a functional does not substantially affect the effective band masses and deformation potentials as long as a physically correct representation of the conduction band states near the band gap has been obtained. Fitting of the electron-phonon matrix elements obtained in density functional perturbation theory (DFPT) with the LDA excluding spin orbit interaction (SOI) gives $\Xi^{\text{L}}_u = 7.0$~eV and $\Xi^{\text{L}}_d = 0.4$~eV. Computing the relative shifts of the L valleys induced by strain with the HSE03 functional including SOI gives $\Xi^{\text{L}}_u = 5.5$~eV and $\Xi^{\text{L}}_d = 0.8$~eV, in good agreement with the DFPT values. Our calculated values of $\Xi^{\text{L}}_u$ agree fairly well with experiment ($\sim 3-4.5$~eV). The computed values of $\Xi^{\text{L}}_d$ are substantially smaller than those obtained by fitting electronic transport measurements ($\sim 17-22$~eV), indicating that intravalley acoustic phonon scattering in PbTe is much weaker than previously thought.