MOLECULAR-DYNAMICS SIMULATIONS OF LOW-ENERGY CASCADES IN BETA-SIC

The dynamics of point defect production in beta-SiC is studied using the Molecular Dynamics (MD) technique. A hybrid pair/three-body potential developed by E. Pearson et al.10 is used to model interatomic forces. The bulk displacement energies are found for Si and C atoms along selected crystallographic directions within the [111] tetrahedral gaps. It is found that Si atoms have higher displacement energies than C atoms for all directions. Si displacement energy is found to be approximately 52 eV, while that of C is only approximately 10 eV through the [111] gap. Focused cascades along the close-packed [111] direction contribute to displacements in beta-SiC but, replacement collision sequences are not likely to occur. Displaced atoms come to equilibrium in hexagonal interstitial sites between the (111) planes in most cases. Also, trivacancies tend to occur on the (111) carbon planes. The equilibrium cascade configurations are observed to be highly non-stoichiometric with the majority of displacements being of C type.