SGER: Exploration of Ordering Mechanisms in the Nucleationless Self-Assembly of Quantum Dot Islands

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This SGER project will explore a unique approach to creating long-range ordered arrays of self-assembled, three-dimensional (3D) quantum dot islands. The concept being explored in this project is that with nucleation-less islanding, periodic arrays of uniformly sized QD islands may form spontaneously under suitable conditions-or may be induced by 'weakly invasive' growth modifiers that promote and enhance existing ordering forces. The research will use growth in an ultrahigh-vacuum system and post-growth, in-situ scanning tunneling microscopy to explore aspects of QD island formation. Epitaxial SiGe alloys on Si(100) will serve as a model system. A range of growth parameters in which islands form without 3D nucleation will be sought. The surface morphology evolution at early stages of heteroepitaxy (before islands with discrete facets form) will be studied to detect possible driving forces for spontaneous self-organization of QD islands into periodic arrays. Additionally, transient straining of the substrate surface by an optical interference pattern as a way of enhancing these driving forces to impose long-range order will be explored. %%% This project will explore a new and innovative approach to creating long-range ordered arrays of self-assembled, three-dimensional (3D) quantum dot islands. The idea being explored involves nucleation-less islanding, whereby periodic arrays of uniformly sized QD islands may form spontaneously under suitable conditions. The project sets specific goals and methods for an initial study to test these ideas, and several key issues can be appropriately addressed and resolved by the project.***