Reaction processes of transition-metal Ni atom with bare Si(001) and H-terminated Si(001)-(2x1) surfaces: First-principles study - art. no. 165309

摘要

We performed first-principles total-energy calculations to investigate the reaction processes, i.e., the adsorption, surface diffusion, penetration, and silicidation, of the transition-metal Ni atom with both the bare Si(001) and H-terminated Si(001)-(2x1) surfaces. We found that, on the bare Si surface, an adsorbed Ni atom readily diffuses on the surface and also penetrates into the subsurface, then it is stabilized in the subsurface sites at room temperature. The penetration of Ni is the precursor state for the silicidation. On the other hand, on the H-terminated Si surface, the surface diffusion of Ni is limited in the valleys between the Si dimer rows at room temperature. In addition, its penetration is blocked, and thus the silicidation is prevented. Comparing the results for Ni on both surfaces, we concluded that the surface hydrogenation suppresses the reactions of Ni with the Si surface. Furthermore, we also found that, by the surface hydrogenation, Ni existing in the Si subsurface is segregated onto the surface top. [References: 30]