COMPARISONS OF AG DEPOSITS ON GE AND SI(111)

Crystal growth and surface diffusion have been studied in the Ag/Ge(11 1) system using ultra-high vacuum scanning electron microscopy (UHV-SE M) based techniques, biassed secondary electron imaging (b-SEI), micro -AES and RHEED. Ag was deposited through and past a mask of holes held close to the substrate at 20<T-d<500 degrees C. Under certain conditi ons, the Ag patches were observed to split into two regions correspond ing to the root 3 x root 3R30 degrees (hereafter root 3) and a lower c overage (4 x 4) structure, each of which were easily observable using b-SEI. These patch widths were measured as a function of T-d, and of a nnealing times at temperatures T-a, and effective diffusion coefficien ts extracted. The coverage of the root 3 Ag/Ge(111) layer is close to 1 ML throughout the temperature range studied, unlike root 3 Ag/Si(111 ), where it depends on deposition and annealing conditions.