The behavior of Si adsorbates which had been evaporated onto an (001) surface was studied by tracing the diffusion which was caused by radiative heating. A reflection electron microscope was used to observe denuded zones that were created at the terrace edge and grew with heating time. The diffusion constants of Si adsorbates were determined by monitoring denuded zone widths on an (001) surface. Diffusion on the 2 x 1 terrace had directions which were parallel to a surface dimer that was connected to 2 nearest-neighbor atoms on the surface. In a similar manner, diffusion on the 1 x 2 terrace had directions which were perpendicular to the dimer. The diffusion constants in the opposite directions were the same for both structures, so isotropic diffusion in the opposite directions was observed on an (001) surface, such that: uD2x1 = dD2x1 = D1x2 and uD1x2 = dD1x2 = D1x2. Here, the u index indicated diffusion from the down-side to the up-side and the d index had the obvious opposite meaning. However, a difference in diffusion constant between D2x1 and D1x2 was observed. It was concluded that D1x2 was some 5 to 6 times as large as D2x1 on the (001) surface.

T.Doi, M.Ichikawa: Japanese Journal of Applied Physics, 1995, 34[I-7A], 3637-41