Simulations of metal(100) homoepitaxy: Submonolayer island formation, {open_quotes}mound{close_quotes} formation during multilayer growth, and kinetic phase transitions to re-entrant smooth growth
- Sandia National Labs., Livermore, CA (United States)
- Ames Lab., IA (United States)
We describe recent developments in the modeling of metal(100) homoepitaxy, and in the interpretation of STM and high-resolution diffraction experiments. Our model includes (I) a detailed description of nucleation and growth of near-square islands in each layer; (ii) an additional barrier to downward transport at island or step edges; and (iii) downward {open_quotes}funneling{close_quotes} of atoms deposited at step-edges to lower fourfold-hollow adsorption sites. For Ag(100), Cu(100), and Fe(100) homoepitaxy, we compare model predictions with observed behavior of the submonolayer island densities and size distributions, as well as layer populations at the onset of multilayer growth. At {open_quotes}low{close_quotes} temperature, T, where island formation is irreversible, we thus determine effective barriers for adatom diffusion on terraces and across step-edges. Adatom-adatom bonding is assessed from the transition to reversible island formation at higher T. Results for multilayer growth show strong dependence of film roughness and morphology on T. At typical T, the presence of step-edge barriers produces {open_quotes}mounds{close_quotes} with fixed average slope. At {open_quotes}low{close_quotes} T, downward funneling dominates, due to higher island and step densities, driving reentrant smooth growth, and eventually a transition from mounded to smooth films. Possible re-emergence of rough growth at {open_quotes}very low{close_quotes} T, due to void formation. is discussed.
- OSTI ID:
- 560411
- Report Number(s):
- CONF-970443--
- Country of Publication:
- United States
- Language:
- English
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