Joint Study on Hydrogen-Mediated Epitaxy

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Our recently discovered phenomena of "hydrogen-mediated epitaxy", in which the epitaxy of a film growing on a Silicon substrate is improved by terminating the substrate by hydrogen atoms, have received considerable attention in connection not only with fundamental science on interaction of hydrogen with surfaces, but also with the possibilities of both the promotion of heteroepitaxy and the formation of atomically abrupt interface. The purpose of this research project is to obtain fundamental data for elucidation of the mechanism of hydrogen-mediated epitaxy on atomic scale, novel development of materials such as semiconductors, metals and ceramics, and fabrication of quantum nano-structures with use of self-organization triggered by atomic hydrogen. The new findings worthy of special mention are as follows.(1)When hydrogen-mediated epitaxy was applied to fabricate a Gedelta -doped structure in Si, the surface segregation of Ge atoms was suppressed in the presence of hydrogen, resulting in improvement of the interface abruptness.(2)When hydrogen-mediated epitaxy was applied to Ge thin film growth on Si substrates dynamically supplied atomic hydrogen during Ge growth acted as a surfactant, which promoted layer-by-layer growth. Hydrogen atoms desorbed from the growth front after adsorption for some residence time, indicating a dynamical effect of hydrogen-surfactant.(3)In the self-organization of 2D metal/Si surface phase into 3D metal clusters triggered by atomic hydrogen, the reconstructed structures of substrate Si atoms were frozen by hydrogen-termination for In/Si and other systems, indicating the possible occurrence of atomic-hydrogen-induced self-organization of substrate Si atoms.These results cause the key of better understanding of mechanism of hydrogen-mediated epitaxy.