FIRST-PRINCIPLES INVESTIGATION OF RADIATION-INDUCED DEFECTS IN SI ANDSIC

We have calculated the displacement-threshold energies for the main sy mmetry directions in Si and SiC using a self-consistent first-principl es method. We show that - depending on the knock-on direction - 64-ato m simulation cells can be sufficient to allow a nearly finite-size-eff ect-free calculation, thus making the use of first-principles methods possible. We use molecular dynamics (MD) techniques and propose the us e of a sudden approximation which agrees reasonably well with the MD r esults for selected directions and which allows estimates of displacem ent-threshold energies without employing an MD simulation. (C) 1998 El sevier Science B.V. All rights reserved.