Research on the controlled growth of Si and Ge nanocrystals in epitaxial fluoride on Si substrates using Si MBE techniques will be conducted. The linear (including photoluminescence) and nonlinear optical properties of these nanocrystals will be studied, along with fundamental efforts to understand and control the optical properties of these nanocrystals. With this information, the potential usefulness of this material will be evaluated for a variety of applications. The research is motivated by the need to fabricate new opto-electronic materials which are easily compatible with silicon Very Large Scale Integration (VLSI) and which can either produce visible light or have large, nonlinear optical coefficients. We are particularly motivated by the recent demonstration of visible light photoluminescence from porous Si, and believe the work proposed here will give an opportunity to make much more controlled nanocrystal structures and will present more opportunity for electro-luminescence device structures than porous Si if the proposed mechanism of quantum confinement in Si nanocrystals proves to be valid. We are also motivated by recent theoretical and experimental work showing that quantum dots of semiconductors can have very large nonlinear optical properties. %%% Fundamental studies of the epitaxial growth and the optical properties of very small crystallites (nanocrystals) will be carried out. These nanocrystals will be fabricated with techniques potentially compatible with silicon Very Large Scale Integration (VLSI), and may lead to the fabrication of new opto-electronic materials allowing monolithic fabrication of devices which utilize VLSI digital processing and optical communication and/or processing for faster, more efficient computing and information processing in the future.
