First principles simulations of antiphase defects on the SP 90 degrees partial dislocation in silicon

Abstract

We study the structure and energies of formation of antiphase defects on the single period (SP) 90 degrees partial dislocation in silicon using a first principles density functional method. We consider two types of antiphase defect, the type first proposed by Hirsch (1980 J. Microsc. 118 3) wholly inside the dislocation core, and another type that lies partly outside the core. Both types are stable and contain one atom which is threefold coordinated. Each of these atoms has a dangling hybrid which lies in a direction perpendicular to the dislocation line on the slip plane. We obtain values of 1.39 +/- 0.03 eV and 1.41 +/- 0.03 eV for the average formation energy of single antiphase defects of the inside and outside types, respectively. We have obtained, using a tight binding scheme, bandstructures corresponding to these two types of defect, and we find both of them to be associated with states in the gap and each dangling hybrid to contain one electron.