Nanostructures And Diffusion Behaviors On Si(100) Surface

The deposition of single Si ad-specie (adatom and ad-dimer) on the p(2.2) reconstructed Si(l00) surface has been simulated by an empirical tight-binding (ETB) method. Using the clean and defective Si surfaces as the deposition substrates, the deposition energies are mapped out around the clean surface, dimer vacancies,steps and kink structures. From the calculated energy plots, the binding sites, saddle points and several possible diffusion paths are achieved. During the analysis of the deposition and diffusion behaviors, the influences of the surface defects or microstructures can be seen. At the same time, the corresponding diffusion temperatures are estimated. Diffusion on the clean surface has large anisotropy, and this anisotropy will be decreased due to the introduced dimer vacancies. Although the adatom can move into the dimer vacancy easily, it cannot fill into it efficiently since it can also move out of the dimer vacancy easily. Around B-type steps, it is easy for the adatom to move from the upper or lower terraces to the step edges or the kink structures forming crystal growth. As it come to ad-dimer, it is easy to form stable state Al and metal stable state A2 on the clean surfae. The change from Al to A2 state appears as the rotation of the ad-dimer. The ad-dimers are found to be prefer to fill into the missing dimer vacancies. Finally, the diffusion and deposition traces of the ad-dimers on the clean and defective surfaces have been simulated.