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Nonequilibrium Interface and Surface Dynamics 2007
Surface Relaxation vs. the Ehrlich-Schwoebel
Effect in Thin-film Growth
CSIC Building (#406),
Seminar Room 4122.
Surface Relaxation vs. the Ehrlich-Schwoebel Effect
in Thin-film Growth
University of California, San Diego
The surface of an epitaxially growing thin film
often exhibits a mound-like structure with its
characteristic lateral size increasing in time.
In this talk, we consider two competing mechanisms
for such a coarsening process:
(1) surface relaxation described by high-order
gradients of the surface profile; and
(2) the Ehrlich-Schwoebel (ES) effect which is the
upper-lower terrace asymmetry in the adatom
attachment and detachment to and from atomic steps.
We present a theory based on a class of continuum
models that are mathematically gradient-flows of
some effective free-energy functionals describing
these mechanisms. This theory consists of two parts:
(1) variational properties of the energies, such as
`ground states' and their large-system-size asymptotics, showing the unboundedness of surface
slope and revealing the relation between some of the
(2) rigorous bounds for the scaling law of the
roughness, the rate of increase of surface slope,
and the rate of energy dissipation, all of which
characterize the coarsening process. Comparison of
our theory with experiments will be made; and
physical consequences of mathematical investigations
will be emphasized.