Theoretical Study Of Characteristic And Homogeneity Growth On Hydrogenated Si Surface Using Empirical Tight-Binding Method

The energetic and structural properties of SiH₂ adsorbed on single dimer vacancy (SDV) of the Si(100)-c(4×2) surface, the structures of 0.5ML hydrogenated Si(100) surface and the deposition and diffusion behaviours of silicon adatom on the H-terminated Si (100) surfaces have been studied by using empirical tight-binding (ETB) total energy calculations. The adsorptions of SiH₂, SiH₂ with a hydrogen adatom (SiH₂+H) and SiH₂ with two hydrogen adatoms (SiH₂+2H) on the Si (100) surface near SDV structure have been calculated. Three possible sites are found in each case, and the presenting of hydrogen may reverse the relative stability of these sites. The energies of different structures of 0.5ML hydrogenated Si(100) surface have been calculated, and two most stable structures are obtained. One stable structure agrees with the experimental report. Simultaneity, the adsorption energies of single Si adatom on the H-terminated Si (100) surfaces are specially mapped out in this paper, from which the favorite binding sites and possible diffusion pathways have been achieved. The variety of the diffusion anisotropy with the coverage transforming is obtained. The energy barriers of the adatom diffusion are found to be higher than that on the clean surface, because the H atoms saturate the dangling bonds of the surface Si atoms. Near the SDV, the diffusion energy barriers of the adatoms on hydrogenated Si (100) surfaces are higher than those of non-hydrogenated, and the SDV is found to be good adsorption point. With the shortening of the structural period, it takes more energy for the adsorbed atom to escape from the SDV.