THE PINNING EFFECT OF PHOSPHORUS ON DISLOCATION CORES IN SILICON

The interaction of phosphorus with 90 degree partial dislocations in silicon is examined using a cluster method with local density functional pseudopotential theory. We describe several states of phosphorus at dislocation cores which are (i) normally reconstructed and (ii) which contain solitonic reconstructed bonding patterns. Our overall conclusion is that there is a clear tendency for phosphorus to migrate towards the dislocation core, and assume three fold coordination, thus (i) breaking reconstructed bonds across the core and (ii) passivating the solitonic dangling bonds. In each case the P loses its donor characteristic.