MICROPROBE RHEED AND SREM STUDIES OF SI MBE ON GA-ADSORBED SI(111) SURFACE

Molecular beam epitaxial (MBE) growth of silicon on the gallium-adsorbed Si(111)square-root 3 x square-root 3 surface structure is investigated by microprobe reflection high-energy electron diffraction (RHEED) and scanning reflection electron microscopy (SREM). Improvement in crystallinity is observed for a Si film grown on a Ga-adsorbed surface compared with that grown on a clean Si(111)7 x 7 surface structure. Substrate temperature dependence of the denuded zone width of two-dimensional (2D) Si nuclei is measured for various growth rates. The measurements give the activation energy of surface diffusion and the critical 2D nucleus size. Due to gallium absorption on the surface, the activation energy becomes lower and the size becomes larger than on the clean Si surface. This improves the crystallinity of the grown film. Si MBE growth on partially adsorbed surfaces is also reported. It is found that a film with good crystallinity grows selectively on the Ga-adsorbed area with a stripe shape.