CORRELATION BETWEEN THE GETTERING EFFICIENCIES AND THE ENERGIES INTERFACES IN SILICON BICRYSTALS

A comparative study of the gettering efficiency of the twin grain boun daries Sigma=25, Sigma=13, and Sigma=9 has been carried out by means o f electron-beam-induced current measurements performed on quenched sil icon bicrystals precontaminated by Cu or Ni. The extent of the denuded zone appearing on both sides of each interface type has been consider ed as the ''rating'' of its gettering efficiency. For both contaminant s, the same scaling of the gettering efficiencies of the boundaries ha s been observed and was found to be in the order Sigma=9 much less tha n Sigma=13<Sigma=25. To account for this ranking, we have correlated t he gettering efficiency to the excess energy of the grain boundary wit h respect to the bulk energy, as theoretically calculated. The computa tional procedures have been performed by means of molecular-dynamics s imulations using several potentials, On the basis of the specific diso rder affecting the Sigma=25 structure upon heat treatment, our calcula tions provided the same progression for the interfacial energies as th at observed experimentally for the gettering efficiencies of the corre sponding grain boundaries according to the extents of the appropriate denuded zones. Calculations of the strain fields developed by the thre e grain boundaries also support this view. (C) 1996 American Institute of Physics.