Diffusion Of Ag Adatom Research Articles

First-principles study of Sb adsorption on Ag(1 1 0)(2 × 2)

The adsorption of antimony atom on the Ag(1 1 0) surface has been studied within the density functional theory framework. It was turned out that Sb–Ag surface alloy was formed in which Sb atoms substitute Ag atom in the outermost layer and subsurface site absorption was not preferred, suggesting that Sb is well segregated to the surface. Geometric analysis showed that rumpling between substitutional Sb and Ag in the alloy surface is negligible. These results are found to agree well with the experimental finding of Nascimento et al. [Surf. Sci. 572 (2004) 337]. In addition, investigation of the diffusion of Ag atom on bare and Sb-covered Ag(1 1 0) surface showed that Ag adatoms will jump along the so call in-channel direction and Sb substitution has little effect on the diffusion of Ag adatoms on Ag(1 1 0) surface. Such diffusion behavior was found to be different from that of Ag adatoms on Ag(1 1 1) surface, where the diffusion energy barrier was reported to be significantly increased upon Sb substitution [Phys. Rev. Lett. 73 (1993) 2437].

Diffusion of Ag adatom on the H-terminated and clean Si(111) surfaces: A first-principles study

Using a first-principles calculation method, we investigate the adsorption and diffusion of a Ag adatom on the H-terminated and clean Si(111) surface, which would be useful in understanding the initial stages of metal growth on semiconductor substrates. We perform extensive searches for metastable surface structures induced by the Ag adatom adsorption, and then find its diffusion barriers and pathways on both kinds of the substrates. The calculated barrier for the Ag atom on the H-terminated surface is only 0.14 eV. On the clean surface, the diffusion barriers inside a half\char21{}unit cell (HUC) and between HUC's are calculated at 0.27 and 0.88 eV, respectively. The present results provide a qualitative description of the Ag growth modes on the Si(111) surfaces: the three-dimensional island growth on the H-terminated surface and the formation of the wetting layer on the clean surface. In addition, the calculated barrier of 0.88 eV agrees well with the diffusion barrier measured by recent scanning-tunneling microscopy.