Mass transport on the (111) surface was studied by means of scanning electron microscopy and Auger analysis (with spatial resolution) under ultra-high vacuum conditions. The spreading of Ag deposits was investigated at temperatures ranging from 350 to 450C; where no desorption occurred. In order to avoid electromigration, the samples were heated by using a halogen lamp. When the first islands had formed (Stranski-Krastanov growth), Ag began to spread out of the initial deposit zone. The main features deduced from the concentration profiles were that, at temperatures above about 400C, the profiles exhibited a rather constant concentration that ended in a very sharp front (attributed to an unrolling carpet mechanism). At temperatures below about 400C, the corresponding profiles had 2 gradient zones. In both cases, a t¾ kinetic law was found which suggested that Ag/Si mass transport might be controlled by the surface self-diffusion of Ag atoms, on 3-dimensional Ag islands, with an activation energy of about 2.4eV/atom.

Ag Mass Transport on Si(111) in the 350–450°C Temperature Range. N.Boutaoui, H.Roux, M.Tholomier: Surface Science, 1990, 239[3], 213-21