Theoretical study of stacking faults in silicon

Abstract

The intrinsic and extrinsic stacking faults along the [111] direction in silicon are studied within the local-density-functional approach with ab initio pseudopotentials using a plane-wave basis set. The stacking-fault energy is obtained from first principles and is found to be in reasonably good agreement with experimental values. Electronic defect states are found within the energy gap. The defect state with energy 0.1 eV above the valence-band maximum is consistent with photoluminescence data. The electron density near the fault is found to deviate only slightly from the perfect crystal. The Hellmann-Feynman force theorem is used to study the forces on atoms near the fault and to determine the resulting structural relaxations. It is found that the interplanar separations increase by about 1% to achieve vanishing forces. This relaxation does not affect appreciably the stacking-fault energy, the eigenvalues, and other electronic properties.