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

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