It was demonstrated, using first-principles calculations, that As segregation in the cores of 90 dislocations occurred in the form of an ordered chain of As atoms lying along the dislocation pipe. All of the As atoms in the chain had 3-fold coordination, due to repulsion between alternating As atoms. It was noted that the overall behavior of single impurities, isolated dimers and chains in the dislocation core was similar to their behavior in Si grain boundaries. However, the segregation energy of both single As atoms and those in a chain were much larger in the dislocation core. In the case of the chain, the energy could be as high as 0.9eV per As atom.

A.Maiti, T.Kaplan, M.Mostoller, M.F.Chisholm, S.J.Pennycook, S.T.Pantelides: Applied Physics Letters, 1997, 70[3], 336-8