AG GROWTH ON SI(111) WITH AN SB SURFACTANT INVESTIGATED BY SCANNING-TUNNELING-MICROSCOPY

We have investigated a room-temperature growth mode of ultrathin Ag fi lms on a Si(lll) surface with an Sb surfactant using STM in a UHV syst em. On the Sb-passivated Si surface, small sized islands were formed u p to 1.1 ML, Flat Ag islands were dominant at 2.1 ML. coalescing into larger islands at 3.2 ML. Although the initial growth mode of Ag films on the Sb-terminated Si(lll) surface was Volmer-Weber (island growth) , the films were much more uniform than Ag growth on clean Si(lll) at the higher coverages. From the analysis of STM images of Ag films grow n with and without an Sb surfactant, the uniform growth of Ag films us ing an Sb surfactant appears to be caused by the kinetic effects of Ag on the preadsorbed Sb layer. Our STM results indicated that Sb suppre sses the surface diffusion of Ag atoms and increases the AE-island den sity. The increased island density is believed to cause coalescence of Ag islands at higher coverages of Ag. resulting in the growth of atom ically flat and uniform Ag islands on the Sb surfactant layer. (C) 199 7 Elsevier Science B.V.