Atomic-resolution Z-contrast scanning transmission electron microscopy revealed the preferential nucleation of electron beam-induced damage in certain atomic columns of a Si tilt grain boundary. Atomic-scale simulations showed that the region of initial damage nucleation corresponded to columns where the formation energies of vacancies and vacancy complexes were very low. The calculations further predicted that vacancy accumulation in certain pairs of columns could induce a structural transformation into low-density dislocation pipes with all of the atoms being 4-fold coordinated.

Damage Nucleation and Vacancy-Induced Structural Transformation in Si Grain Boundaries A.Maiti, S.T.Pantelides, M.F.Chisholm, S.J.Pennycook: Applied Physics Letters, 1999, 75[16], 2380-2