The core reconstruction of the 90° partial dislocation in silicon

The free energy of a recently proposed new structure for the core of the 90° partial dislocation in Si, displaying double the crystal periodicity along the dislocation line, is found to differ from that of the previously accepted single-crystal period core structure by an insignificant amount at the temperatures at which dislocations become mobile in Si. It is proposed, therefore, that both core structures exist. We have found that, although one should, in principle, be able to distinguish between these core structures with modern 400 kV high-resolution electron microscopes, the published experimental micrographs are unable to distinguish between these competing core structures.