Stacking-Fault Energies in Silicon, Diamond, and Silicon Carbide

Stacking faults in a perfect crystal can be seen as limiting structures of certain series of polytypes of that crystal. A parametrization of the energy of polytypes in terms of interaction constants between layers therefore allows for the calculation of stacking-fault energies. The first-principles pseudopotential-density-functional method is used to calculate total energies of a few simple polytypes of silicon and carbon. The energies of intrinsic and extrinsic stacking faults (γISF and γESF , respectively) in silicon and diamond that follow from these calculations are in much better agreement with available experimental numbers than in previous theoretical approaches. I find: γISF = 47 mJm-2 and γESF = 36 mJm-2 for Si, γISF = 300 mJm-2 and γESF = 253 mJm-2 for diamond. From recently published similar calculations for polytypes of silicon carbide one obtains a negative energy for the extrinsic stacking fault, if zincblende silicon carbide is taken as the unfaulted structure, suggesting the observed occurrence in nature of polytypism in silicon carbide.