A RHEED study of the surface reconstructions of Si(001) during gas source MBE using disilane

Abstract

The growth of Si(001) from a gas-source molecular beam epitaxy system (Si-GSMBE) using disilane (Si 2H 6) was investigated using RHEED. Substrates were prepared by two commonly used etching techniques, one producing a surface oxide and the other a hydrogen passivated surface. Comparisons are made with regard to the growth mode and quality of the overlayer. Surface reconstructions which occurred during growth were studied as a function of both substrate temperature and surface coverage. All growth was found to be initiated by the formation of three-dimensional (3D) islands which coalesced at substrate temperatures above 600°C. Near 645°C, (2 × 2) and c(4 × 4) reconstructions occurred on the growing Si(001) surface. At higher temperatures, growth was found to proceed two-dimensionally. The Si(001) surface was found to have undergone a series of reconstructions which may be related to the number of hydrogen adatoms and Si dimers covering the surface.