Modeling of Diffusivity for 2D Vacancy Nanopits and Comparison with 2D Adatom Nanoislands on Metal(100) Surfaces Including Analysis for Ag(100)
- Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy
- Ames Lab. and Iowa State Univ., Ames, IA (United States)
- Ames Lab. and Iowa State Univ., Ames, IA (United States). Dept. of Chemistry, and Dept. of Materials Science & Engineering
- Iowa State Univ., Ames, IA (United States). Dept. of Physics & Astronomy, and Dept. of Mathematics
Diffusion coefficients, DN, for 2D vacancy nanopits are compared with those for 2D homoepitaxial adatom nanoislands on metal(100) surfaces, focusing on the variation of DN with size, N. Here, N is measured in missing atoms for pits and adatoms for islands. Analysis of DN is based on kinetic Monte Carlo simulations of a tailored stochastic lattice-gas model, where pit and island diffusion are mediated by periphery diffusion, i.e., by edge atom hopping. Precise determination of DN versus N for typical parameters reveals a cyclical variation with an overall decrease in magnitude for increasing moderate O(102) ≤ N ≤ O(103). Monotonic decay, DN~ N-β, is found for N ≥ O(102) with effective exponents, β = βeff, for both pits and islands, both well below the macroscopic value of βmacro = 3/2. DN values for vacancy pits are significantly lower (higher) than for adatom islands for moderate N in the case of low (high) kink rounding barrier. However, DN values for pits and islands slowly merge, and βeff → 3/2 for sufficiently large N. The latter feature is expected from continuum Langevin formulations appropriate for large sizes. Finally, we compare predictions from our model incorporating appropriate energetic parameters for Ag(100) with different sets of experimental data for diffusivity at 300 K, including assessment of βeff, for experimentally observed sizes N from ~100 to ~1000.
- Research Organization:
- Ames Laboratory (AMES), Ames, IA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)
- Grant/Contract Number:
- AC02-07CH11358; CHE-1507223
- OSTI ID:
- 1422773
- Report Number(s):
- IS-J-9530; TRN: US1801661
- Journal Information:
- Journal of Physical Chemistry. C, Vol. 122, Issue 21; ISSN 1932-7447
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Nanoscale modification of silicon and germanium surfaces exposed to low-energy helium plasma
|
journal | July 2019 |
Similar Records
Diffusion of two-dimensional epitaxial clusters on metal (100) surfaces: Facile versus nucleation-mediated behavior and their merging for larger sizes
Communication: Diverse nanoscale cluster dynamics: Diffusion of 2D epitaxial clusters