The diffusion behaviour of dimer vacancies on a Si(100)-(2 x 1) surface was studied by using ultrahigh-vacuum scanning tunnelling microscopy. The dimer vacancies were created by oxygen etching of Si atoms at elevated temperatures. By annealing the sample at 600 to 750C, the dimer vacancies uniformly distribute on the terrace nucleated to form larger elongated voids of one atomic layer deep. The long axis of these voids was parallel to the Si dimer rows. During annealing, the surface morphology evolved in a way dominantly caused by the anisotropic diffusion of the dimer vacancies. A difference of diffusion barriers of 0.17eV was obtained between the [110] and [1¯10] directions.

Anisotropic Diffusion Evolution of Vacancies Created by Oxygen Etching on a Si Surface. S.H.Wang, C.Qun: Chinese Physics Letters, 2011, 28[7], 076801