Quantitative characterization of the Al nanoclustering induced by H interaction with Si(1 0 0)c(4 × 12)-Al surface phase

Self-organized formation of Al nanoclusters (i) induced by interaction of atomic hydrogen with the Si(1 0 0)c(4 × 12)-Al surface and (ii) in the course of Al deposition onto the Si(1 0 0)c(4 × 12)-Al surface has been quantitatively characterized using scanning tunneling microscopy measurements of the Al nanocluster number density. The obtained data have been evaluated within the framework of nucleation rate theory. In the case of Al nanoclustering upon Al deposition at 350–600 K, the changeover of the critical cluster size has been revealed at about 500 K. In the case of H-induced nanoclustering at 400–650 K, the changeover of the rate-limiting process has been detected at about 550 K, namely, at lower temperatures the rate-limiting process is the H-induced detachment of Al atoms from the Si(1 0 0)c(4 × 12)-Al phase, while at higher temperatures this is a competition between H adsorption and desorption at the surface. Activation energy of surface diffusion of Al atoms on the Si(1 0 0)c(4 × 12)-Al surface has been found to be 0.99 eV. Activation barrier for Al detachment from the Si(1 0 0)c(4 × 12)-Al has been estimated to be 1.53 eV.