First-principles study of stair-rod dislocations in si and GaAs stacking-fault tetrahedron defects

摘要

Atomic and electronic structures of stair-rod dislocations, which are produced at ridges of stacking-fault tetrahedron, are studied using the first-principles calculations. It is shown that atoms at the dislocation core produce parallel or zigzag double dimer-bond arrays along the dislocation. In case of GaAs, deep-level bands appear in the band gap due to the misvalency of Ga-Ga or As-As dimer bonds. We found that the symmetry breaking of dimer-bond length occurs between two neighboring arrays to stabilize such deep-level bands.