Structural transformation in the 90° partial dislocation in Si due to Ga impurities

Ga impurities in the 90 degrees Shockley partial dislocation in silicon have been investigated using first-principles total-energy pseudopotential calculations. The results indicate that Ga segregates to the core of the dislocation and destabilizes the asymmetric fourfold coordinated structure, which is known to be the low-energy configuration in pure Si. The segregation energy for Ga in the symmetric core configuration is 0.53 eV/atom. The atomic mechanism for this spontaneous transformation to the symmetric structure is the passivation of quasifive-fold sites in the symmetric core by Ga. [S0163-1829(98)01744-5].