Improved Calculation of Acoustic Deformation Potentials from First Principles

TL;DR

This paper presents a first-principles method using DFT and DFPT to accurately calculate acoustic deformation potentials, enabling better prediction of charge transport properties in materials without relying on empirical data.

Contribution

The authors develop an improved first-principles approach to compute acoustic deformation potentials, reducing dependence on empirical assumptions and enhancing accuracy for materials with limited experimental data.

Findings

Calculated deformation potentials for Si match literature.

Deformation potentials for diamond are larger than previous estimates.

Good agreement for cBN deformation potential, despite lack of experimental data.

Abstract

Using density functional theory (DFT) and density functional perturbation theory (DFPT), the band structure, phonon dispersion and electron phonon coupling matrix were calculated for silicon (Si), diamond and cubic boron nitride (cBN). From these, the acoustic deformation potential was calculated for multiple angles between the electron and phonon wave vectors and analytic expressions for the longitudinal and acoustic modes were fit to find an average deformation potential. The ability to calculate the deformation potential from first principles allows for the scattering rates to be determined without the use of lengthy empirical methods. For Si, the numerically calculated deformation potentials are in excellent agreement with what is seen in the literature. On the other hand, the deformation potentials calculated for diamond were found to be larger than what has been seen previously, however previous calculations of transport parameters in diamond report a large range of values for scattering parameters which may be due to assumptions made in each model. Excellent agreement was also seen between the value calculated for cBN and the literature, however there are no experimental results for cBN and so this value is compared against an estimate. This shows that scattering parameters can be calculated via first principles for materials with sparse experimental data, which in turn allows for increased confidence in the output of charge transport simulations of new and emerging materials.