Wannier interpolation of the electron-phonon matrix elements in polar semiconductors: Polar-optical coupling in GaAs

TL;DR

This paper extends Wannier interpolation to include polar-optical coupling in polar semiconductors, enabling accurate calculations of electron-phonon interactions and relaxation processes in materials like GaAs.

Contribution

It introduces a generalized Wannier interpolation method for polar-optical coupling, validated against experimental data for GaAs, and explores energy-dependent scattering mechanisms.

Findings

Good agreement with experimental band widths and exciton broadenings.

Fröhlich interaction dominates near valley minima, intervalley scattering at higher energies.

Method enables improved optical and transport property calculations.

Abstract

We generalize the Wannier interpolation of the electron-phonon matrix elements to the case of polar-optical coupling in polar semiconductors. We verify our methodological developments against experiments, by calculating the widths of the electronic bands due to electron-phonon scattering in GaAs, the prototype polar semiconductor. The calculated widths are then used to estimate the broadenings of excitons at critical points in GaAs and the electron-phonon relaxation times of hot electrons. Our findings are in good agreement with available experimental data. Finally, we demonstrate that while the Fr\"ohlich interaction is the dominant scattering process for electrons/holes close to the valley minima, in agreement with low-field transport results, at higher energies, the intervalley scattering dominates the relaxation dynamics of hot electrons or holes. The capability of interpolating the polar-optical coupling opens new perspectives in the calculation of optical absorption and transport properties in semiconductors and thermoelectrics.