Electron-Defect Scattering from First-Principles Calculations

Materials contain defects that can significantly impact charge transport. While ab initio calculations have focused on electron-phonon scattering and the phonon-limited mobility, electron-defect (e-d) scattering controls the mobility at low temperature and at room temperature in materials with impurities, dislocations, and interfaces. We present a new ab initio approach to compute the e-d scattering rate due to neutral defects. The formalism relies on 1st-order perturbation theory, where the perturbation is the difference of the Kohn-Sham potentials between a pristine material and the material with a defect. We discuss numerical treatments of the local and non-local parts of this perturbation potential, and effective computation of the associated e-d scattering matrix elements. Using silicon as a case study, we show that the contribution to scattering from the nonlocal part of the pseudopotential, which was neglected in previous work, can be large and unpredictable a priori. We present converged e-d scattering rates for electrons in silicon and graphene due to a range of defects including vacancies, interstitials, and impurities. Using the Boltzmann transport equation, we carry out the first fully ab initio computation of the defect-limited carrier mobility at low temperature.