Research Activities > Programs > Nonequilibrium Interface and Surface Dynamics 2007

Self-assembly of Nanostructures on Topographically Pattern Substrates

CSIC Building (#406), Seminar Room 4122.
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Self-assembly of Nanostructures on Topographically Pattern Substrates

Professor Robert Kukta

State University of New York at Stony Brook


Abstract:   A large obstacle to taking nanotechnology from the research lab to the consumer market is the development of low-cost techniques for fabricating stable and device-specific nano-scale structures. One candidate is self-assembly, whereby a desired structure is allowed to form by natural processes. Self-assembly is an old technologyalloys like steel are regularly heat treated to form particular microstructures that exhibit high strength and toughness. However, controlling self-assembly by heat treatments and similar weakly guided processes is limited, as few and only very simple structures are possible. Techniques with greater flexibility and control are needed to fabricate devices of even modest levels of complexity. A promising route to controlling the formation of nanostructures is combining self-assembly with well-established techniques for patterning at the micro-scale. Relatively large-scale features provide a template for the organization of smaller features. The problem and topic of this talk is to determine what are the large-scale features needed to drive the formation of a particular nanostructure. Focus is on the self-assembly of material deposits (quantum dots or islands) grown by strained-layer epitaxy on a topographically patterned substrate. Prior to growth, features are introduced on the substrate by a method such as lithography and ion-etching. These features guide morphological development by providing preferred sites for islands to nucleate and grow. While it is known from experiment that the arrangement of islands on patterned substrates is affected both by energetic and kinetic phenomena, the nature of these effects has not been well characterized. There have been few analytical and computational efforts to understand where islands form and why and how they develop at particular sites. This talk offers some new insight, drawn from continuum and mesoscale models and simulations. The focus is on structures that form on two-dimensional sinusoidal patterns and three-dimensional raised mesa patterns.

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