Cooperative Atomic Dynamics in Crystalline Cages - From Defect Complexes To Self-assembled Nanostructures

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9803768 Pantelides This award supports electronic structure theory investigations of atomic-scale mechanisms that underlie the nucleation and growth of nano-scale structures. The PI's previous work has shown that the study of defect complexes can lead to the prediction of potentially self-assembled, novel, ordered structures of point defects or defect complexes. These structures correspond to a subtle balance between `chemistry' that leads to low coordination and `crystallinity' that generally dictates high coordination. The proposed research entails the investigation of specific systems, selected because of the anticipated effect of defect complexes on the material's electrical and optical properties; the demonstrated or anticipated self-assembly of ordered structures with potential for nanodevices or nanowires; anticipated novel interplay between `chemistry' and `crystallinity'; or any combination of these criteria. Examples include the possibility of ordered F impurities in Si that may lead to embedded nanowires and the nucleation and growth of As complexes that may control both the properties of the low-temperature-grown GaAs and the observed self-assembly of ordered spherical As precipitates. %%% The PI will perform computational research on atomic length scales to determine how specific defects in materials affect their electronic and optical properties and how desirable defects can be introduced into a material. The purposeful manipulation of defect structures in materials to produce specific properties holds promise for the `engineering' of electronic devices on the atomic scale. ***