AVS 58th Annual International Symposium and Exhibition
    Surface Science Division Wednesday Sessions
       Session SS1-WeM

Paper SS1-WeM6
Nucleation and Growth of Ag Islands on the (√3x√3)R30o Phase of Ag on Si(111)

Wednesday, November 2, 2011, 9:40 am, Room 107

Session: Atomistic Control of Structure & Evolution
Presenter: Alex Belianinov, Iowa State University & Ames Laboratory - US DOE
Correspondent: Click to Email
Using STM, we measure densities and characteristics of Ag islands that form on the (√3x√3)R30o-Ag phase on Si(111), as a function of deposition temperature between 50 and 300 K. Assuming that Ag diffusion occurs via thermally-activated motion of single atoms between adjacent sites, the data can be explained as follows. At 50-125 K, islands are relatively small, and island density decreases only slightly with increasing temperature; the island density does not follow conventional Arrhenius scaling, probably due to limited mobility and lack of steady-state between deposition and consumption of Ag atoms. At higher temperatures there is a transition to conventional Arrhenius scaling, from which a diffusion barrier of 0.20-0.23 eV can be derived. At 300 K Ag atoms can travel for distances on the order of 1 µm, and they nucleate preferentially at step bunches. We have used this information to nannopattern the surface with Ag. We have done this by creating artificial defects in the √3-Ag structure with the STM tip, and then subsequently depositing Ag at 300 K. This leads to strong preferential aggregation at these sites.