PREFACTOR AND STEP-EDGE BARRIER DETERMINATION FOR INTERLAYER DIFFUSION IN HOMOEPITAXIAL SYSTEMS - AG AG(111)/

Interlayer diffusion is controlled by the probability that an atom wil l hop from a higher to a lower level. This probability depends on the additional step edge barrier Delta E-s which an atom experiences at a step because of the lower coordination as it moves over the;barrier, a nd possibly on the different prefactors v(s), v(t) for an atom at the step versus one at a terrace position. It is important to develop expe rimental methods that separate out the two contributions. We have rean alyzed the STM-based method,(1) which measures the fraction of islands with second layer occupation at different deposition temperatures, to show how the two contributions can be identified. In addition, we hav e developed a diffraction-based method that measures the step density of nucleated islands as they compete for atom capture with the steps a t the perimeter of the terraces. RHEED experiments on Ag/Ag(lll) resul t in Delta E-s = 0.15 +/- 0.03 eV and v(s)/v(t) = 2.3 x 10(2+/-0.2), i n good agreement with the results, Delta E-s = 0.13 +/- 0.03 eV and v( s)/v(t) = 10(3+/-0.3), deduced from the data of Ref. 1.