AVS 51st International Symposium
    Surface Science Thursday Sessions
       Session SS3-ThA

Paper SS3-ThA9
Temperature-Dependence of Submonolayer Island Structure and Multilayer Growth Morphologies in Ag/Ag(111) Homoepitaxy

Thursday, November 18, 2004, 4:40 pm, Room 213B

Session: Surface Diffusion and Transport
Presenter: M. Li, Iowa State University
Authors: M. Li, Iowa State University
E. Cox, Iowa State University
C. Chung, Iowa State University
C. Ghosh, Iowa State University
J. Evans, Iowa State University
P.A. Thiel, Iowa State University
Correspondent: Click to Email
We have performed STM studies to analyze the irregular structure of submonolayer islands and the rough wedding-cake-like multilayer growth morphologies formed during Ag/Ag(111) homoepitaxy between 120-180K. Previous STM and surface scattering studies have probed only selected aspects of these features of film structure, which are expected due to restricted periphery diffusion (PD) and limited interlayer transport. However, no comprehensive real-space characterization of film morphology across this temperature regime has been available. KMC simulation of atomistic lattice-gas models is also viable in this regime where island separations are below ~100nm, and film morphology is not controlled by dislocations (in contrast to behavior at 300K). We have thus also developed a realistic atomistic model to describe the submonolayer growth of individual islands, and thereby quantified the observed transition with increasing temperature from dendritic shapes with triangular envelopes (due to anisotropy in incorporation at corners) to more isotropic fractal shapes (reflecting high edge and kink rounding barriers), and then to compact shapes (reflecting efficient PD). More complete modeling of the overall island nucleation and growth process revealed a transition to reversible island nucleation in this temperature range. Finally, by extending of our realistic model for submonolayer island formation to the multilayer regime incorporating negligible interlayer transport, we described quantitatively the observed kinetic roughening and wedding-cake-like growth morphologies.