20 research outputs found
Interplay between kinetic roughening and phase ordering
We studied interplay between kinetic roughening and phase ordering in 1+1
dimensional single-step solid-on-solid growth model with two kinds of particles
and Ising-like interaction. Evolution of both geometrical and compositional
properties was investigated by Monte Carlo simulations for various strengths of
coupling. We found that the initial growth is strongly affected by interaction
between species, scaling exponents are enhanced and the ordering on the surface
is observed. However, after certain time, ordering along the surface stops and
the scaling exponents cross over to exponents of the Kardar-Parisi-Zhang
universality class. For sufficiently strong strength of coupling, ordering in
vertical direction is present and leads to columnar structure persisting for a
long time.Comment: 8 pages, EUROLaTeX, 3 ps figures, submitted to Europhys. Let
Submonolayer growth with decorated island edges
We study the dynamics of island nucleation in the presence of adsorbates
using kinetic Monte Carlo simulations of a two-species growth model. Adatoms
(A-atoms) and impurities (B-atoms) are codeposited, diffuse and aggregate
subject to attractive AA- and AB-interactions. Activated exchange of adatoms
with impurities is identified as the key process to maintain decoration of
island edges by impurities during growth. While the presence of impurities
strongly increases the island density, a change in the scaling of island
density with flux, predicted by a rate equation theory for attachment-limited
growth [D. Kandel, Phys. Rev. Lett. 78, 499 (1997)], is not observed. We argue
that, within the present model, even completely covered island edges do not
provide efficient barriers to attachment.Comment: 7 pages, 2 postscript figure
Kinetics of step bunching during growth: A minimal model
We study a minimal stochastic model of step bunching during growth on a
one-dimensional vicinal surface. The formation of bunches is controlled by the
preferential attachment of atoms to descending steps (inverse Ehrlich-Schwoebel
effect) and the ratio of the attachment rate to the terrace diffusion
coefficient. For generic parameters () the model exhibits a very slow
crossover to a nontrivial asymptotic coarsening exponent .
In the limit of infinitely fast terrace diffusion () linear coarsening
( = 1) is observed instead. The different coarsening behaviors are
related to the fact that bunches attain a finite speed in the limit of large
size when , whereas the speed vanishes with increasing size when .
For an analytic description of the speed and profile of stationary
bunches is developed.Comment: 8 pages, 10 figure
Crossover effects in the Wolf-Villain model of epitaxial growth in 1+1 and 2+1 dimensions
A simple model of epitaxial growth proposed by Wolf and Villain is
investigated using extensive computer simulations. We find an unexpectedly
complex crossover behavior of the original model in both 1+1 and 2+1
dimensions. A crossover from the effective growth exponent to is observed in 1+1
dimensions, whereas additional crossovers, which we believe are to the scaling
behavior of an Edwards--Wilkinson type, are observed in both 1+1 and 2+1
dimensions. Anomalous scaling due to power--law growth of the average step
height is found in 1+1 D, and also at short time and length scales in 2+1~D.
The roughness exponents obtained from the
height--height correlation functions in 1+1~D () and 2+1~D
() cannot be simultaneously explained by any of the continuum
equations proposed so far to describe epitaxial growth.Comment: 11 pages, REVTeX 3.0, IC-DDV-93-00