Formation process of very thin Ag structures on Ge(0 0 1) surface below RT

Submonolayer Ag deposited Ge(0 0 1) surfaces at 90 K were observed by scanning tunneling microscopy at various temperatures between 65 and 240 K. At 78 K, there are seven configurations of bright dots made of a Ag atom or their aggregates and adsorbed on clean Ge(0 0 1) surfaces. These dots thermally diffuse on the Ge surface. By annealing above 100 K, they form various dimers, trimers and clusters elongating along both directions of the Ge dimer and the Ge dimer row. When the surface is annealed at 240 K, parts of the elongated clusters change into the different structures that have been observed at room temperature. With increasing temperature from 90 K, diffusion, clustering and intermixing lead to the formations of the surface alloys or compounds made of Ag and Ge.