First-Principles Study of Point-Defect Production in Si and SiC

Abstract

ABSTRACTWe have calculated the displacement-threshold energy Ed for point-defect production in Si and SiC using empirical potentials, tight-binding, and first-principles methods. We show that—depending on the knock-on direction—64-atom simulation cells can be sufficient to allow a nearly finite-size-effect-free calculation, thus making the use of first-principles methods possible. We use molecular dynamics (MD) techniques and propose the use of a sudden approximation which agrees reasonably well with the MD results for selected directions and which allows estimates of Ed without employing an MD simulation and the use of computationally more demanding first-principles methods. We compare our results for Ed with the available experimental values. Furthermore, we have examined the temperature dependence of Ed for C in SiC and found it to be negligible.