Monitoring and Enhancing Molecular Beam Epitaxy Using Low Energy Ion Scattering

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Research to extend the control of surface processes during molecular beam epitaxy will be conducted. The approach is to use ion scattering from the growth surface, allowing both ion scattering spectroscopy (ISS), at low ion fluxes, and controlled growth mode modification at higher fluxes. ISS provides composition analysis of the first atomic layer of the surface providing alloy composition control and control of layer thicknesses in the monolayer range. Glancing angle ions, obtained using the ISS ion source, provide a unique method for tailoring surfaces since shadowing effects can be used to focus ion energy at specific surface sites. For example, impingement angles where energy is deposited at surface defects, but not at perfect regions, can be used to enhance adatom mobilities, flatten surfaces, or improve the ordering of surface steps. %%% While molecular beam epitaxy (MBE) has led to tremendous advances in solid state physics and semiconductor devices, it is not optimum for device production. This research seeks to better understand fundamental processes occuring during MBE at the atomic level, and to overcome one of the major hurdles to the use of MBE on a larger scale.