Preferential arrangement of uniform Mn nanodots on Si(111)-7x7 surface

Under proper growth conditions, ordered and uniform Mn nanodots were fabricated on the Si(111)-7x7 surface without the presence of a wetting layer. Furthermore, the Mn nanodots deposited onto the elevated substrates were observed to occupy preferentially on the faulted half unit cells (FHUCs) of the Si(111)-7x7 surface. This phenomenon implies that the Mn dots adsorbed on the FHUCs is more stable than those adsorbed on the unfaulted half unit cells (UFHUCs). Within the framework of quasiequilibrium thermodynamics, the energy difference between adsorption on the UFHUCs and the FHUCs was estimated to be 0.05eV. The intrinsic attractive potential wells on the FHUCs effectively trap the outdiffusion of Mn atoms, and consequently result in a preferential arrangement of islands with well-defined sizes.