Using first-principles calculations, an investigation was made of electronic charge effects on the structural stability of partial dislocations in Si. For the 30° partial dislocation, it was found that the unreconstructed core sustains all possible charge states associated with the dislocation-related electronic bands, as the Fermi level (µe) sweeps the electronic band gap, while the reconstructed core remained neutral for p-type doping and intrinsic regimes. Both core configurations became negatively charged for n-type doping. In the case of the 90° partial dislocation, the three known core configurations (namely, the single-period and double-period reconstructed cores and the unreconstructed one) remained neutral in the p-type and intrinsic regimes, but the negatively charged states became stable in the n-type region, for all 3 geometries. More importantly, it was found that the relative stability between the 3 structures was strongly charge-state dependent, with the unreconstructed core becoming energetically favorable in the n-type regime. The results provided the required elements for understanding the role of doping in dislocation mobility in semiconductors.

Electronic Charge Effects on Dislocation Cores in Silicon. M.M.de Araújo, J.F.Justo, R.W.Nunes: Applied Physics Letters, 2004, 85[23], 5610-2