Growth Process of Silicon on the Si(111) root 3 X root 3-Ag Surface at Room Temperature

The growth process of silicon on the Si(111)root 3 x root 3-Ag surface (here after root 3Ag surface) has been studied by scanning tunneling microscopy (STM). Islands of one bilayer thickness with infinite form and triangular geometry are observed for 0.32 ML(ML:1 ML= 7.8x10(14) /cm(2)) deposition of silicon on the root 3Ag surface. The orientation of two dimensional islands with triangular geometry is the same as that of unfaulted half unit of the Si(111)7x7 structure (here after 7x7 structure). The surface structure of the Si islands is characterized as the root 3 structure by analysis of STM images of the island. It is believed that Ag atoms segregate on the deposited silicon islands and the island surfaces become the root 3Ag structure. In comparison with densities of the islands on the 7x7 and the root 3Ag surfaces, it is concluded that the diffusion coefficient of Si atoms on the root 3Ag surface is about 60 times larger than that of Si atoms on the 7x7 surface. The value of the diffusion coefficient is independence on deposition rates. We also discuss a possibility of the Schwoebel effect on the root 3Ag surface for Si atoms because populations of the islands at step edges of upper terraces are higher than those at lower step edges.