9618656 Cohen This project addresses dynamical processes of epitaxial growth. For GaAs, the evolution of surface morphology, island formation, crossover to step flow, and the role of adatoms in growth kinetics and morphology will be studied using RHEED and STM. An important goal is to use the knowledge obtained to develop atomic level understanding and control over film growth. Energy-filtered RHEED will be used to improve the comparison with dynamical calculations and to eliminate uncertainties in the measurement of diffuse intensities. Step edge scattering factors will be considered in the correlation function analysis of diffraction. The project will also study GaN growth on bulk GaN platelets(whiskers); this approach is used to remove the role of the amorphous buffer layer normally present with GaN growth on sapphire. The aim is to obtain definitive data on epitaxial processes having direct relationships to microscopic processes of growth. %%% The project addresses forefront research issues in a topical area of materials science having high technological relevance. The research will contribute basic materials science knowledge at a fundamental level to important aspects of electronic/photonic devices and integrated circuitry. Additionally, the fundamental knowledge and understanding gained from the research is expected to contribute in a general way to improving the performance of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area. ***
