First-principles study of point-defect production in Si and SiC

摘要

We have calculated the displacement-threshold energy E_d 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 meth-ods 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 E_d without employing an MD simulation and the use of computationally more demanding first-principles methods. We compare our results for E_d with the available experimental values. Furthermore, we have examined the temperature dependence of E_d for C in SiC and found it to be negligible.