Electron–phonon coupling and associated scattering rates in diamond

Abstract

We calculate the variation of electron–phonon (e–ph) coupling as a function of phonon wavevector and the initial electron energy over the entire Brillouin zone (BZ) in diamond. We consider three cases of the initial electron energy, the first corresponds to an electron at the top of the valence band, the second where the electron is at the conduction band minimum at ∆, and the third is for electrons at the secondary conduction band minimum at Γ. The e–ph interaction exhibits a strong phonon wavevector dependence which indicates a need to go beyond the long-wavelength approximation typically used for treating electron–phonon scattering in transport simulations, especially for capturing high field effects. Within an ab initio electronic structure framework, we describe electron and phonon wavefunctions in terms of localized Wannier functions which allow the evaluation of e–ph coupling over a dense grid in the BZ with tractable computational effort. The full description of the e–ph coupling over the BZ is used to compute the electron linewidth which is applied to predict the associated total phonon scattering rates. Calculations at 0K and 300K are presented and show the corresponding linewidth increases with temperature and that the method is suitable for producing inputs to transport calculations.