The core reconstruction of the 90 degrees partial dislocation in silicon

The free energy of a recently proposed new structure for the core of the 90 degrees partial dislocation in Si, displaying double the crystal periodici ty along the dislocation line, is found to differ from that of the previous ly accepted single-crystal period core structure by an insignificant amount at the temperatures at which dislocations become mobile in Si. It is propo sed, therefore, that both core structures exist. We have found that, althou gh one should, in principle. be able to distinguish between these core stru ctures with modern 400 kV high-resolution electron microscopes, the publish ed experimental micrographs are unable to distinguish between these competi ng core structures.