Research: Simulational and Computational Approach to Condensed Matter Physics
Materials Growth and Deposition
Many of the most significant technological advances today
are directly related to synthesis and processing of materials,
particularly for applications in the electronic and emerging
optoelectronic industries. With the development of atomic dimension
growth and characterization instruments and techniques, modern
materials synthesis and processing has become an enormously complex
field. Because of the increase in the resolution and control
in materials processing it is now impractical to search the experimental
parameter space by empirical methods. It is obvious that our
ability to control the structure and the properties of materials
will require a fundamental level understanding of the intricate
physics of materials growth.
The main impediment to advances in this direction is that
the growth and deposition techniques used in materials processing
involve kinetic far from equilibrium processes which are not
well understood. Even a qualitative understanding of such processes
is difficult because despite its obvious importance in many areas
of science and technology -- from materials science to biology
-- no standard theoretical approach to nonequilibrium phenomena
has yet emerged. In the past few years, however, our research
group has made considerable advances in understanding nonequilibrium
surface and interface growth phenomena through the development
of new concepts and techniques in theoretical, simulational and
experimental studies. In particular, the importance and the role
of nonlinear dynamical processes, scaling and fractals in growth
phenomena has been recognized and novel techniques were introduced
that can be applied to similar processes.
As part of a Materials Theory research grant funded by the
National Science Foundation (NSF grant DMR-9214308) my research
group will develop and apply new computational and simulational
modeling techniques to problems in the growth and deposition
of materials. In particular, we intend to concentrate on the
following specific projects: (1) Order-Disorder Transition in
Epitaxial Growth, (2) Strain Relaxation in Thin Film Growth,
(3) Theoretical Models of Thin Film Growth, (4) Microscopic Modeling
of Chemical Vapor Deposition, and (5) Modeling Porous Silicon.
Although the above projects are focused on specific materials,
we expect that our models will be applicable to a broad range
of related materials and processes. Once their utility in the
proposed projects has been established, we fully expect that
the extension and the application of our models and techniques
to related phenomena will be straightforward.
Far From Equilibrium Phenomena
The key to the solution of many scientific and technological
"Grand Challenge" problems today is a first principle
understanding of the dynamics of interacting many-body systems
far from equilibrium. The reason is that many of the technological
challenges facing different industries today involve nonequilibrium
dynamical processes. For example, understanding how surfaces
are formed and how smooth or rough surfaces can be manufactured
will be crucial in solving major technological problems in such
diverse industries as semiconductors, optoelectronics, petroleum,
paint, chemicals, biotechnology and computers. Therefore any
progress in the direction of a fundamental understanding of far
from equilibrium phenomena would be a major step towards solving
a number of important scientific and technological problems.
Unfortunately, in contrast to equilibrium statistical mechanics,
no standard theoretical framework exists for describing far from
equilibrium phenomena. In recent years, scientific computation
has become the leading technique for studying nonequilibrium
processes and important advances have been made in this direction.
It has now become possible to study the dynamics of such systems
at sufficiently large enough time and length scales to make a
direct comparison with experiments possible.
As part of a research program funded by the Office of Naval
Research my research group will apply computational approaches
including coarse-grained parallel computers to investigate a
number of projects involving interacting many-body systems far
from equilibrium. The general areas of proposed research are:
(1) Dynamics of Growing Surfaces and Interfaces, (2) Cluster
Growth Phenomena, and (3) Self-Organized Criticality. We plan
to carry out large-scale numerical solutions of nonlinear models
and continuum equations (nonlinear PDEs) for surface and interface
growth, and self-organized criticality. We are also studying
detailed models that will be studied using Monte Carlo, Molecular
Dynamics and hybrid Monte Carlo/Molecular Dynamics techniques
in order to understand the role of surface diffusion in surface
growth, growth competition and universality in aggregation processes,
and the dynamics of unstable interfaces in cluster growth. We
will also develop Lattice Gas models to study the dynamics of
two-fluid flow in porous media and past rough surfaces, problems
which are closely related to turbulence and interfacial dynamics.
We expect that our computational techniques and modeling approaches
will be useful in the study of many related problems in the study
of many-body systems far from equilibrium.
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