Study on electron-beam-induced excitation on Si surfaces

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This research aims at investigating atomic-scale crystal growth techniques for IV group semiconductors which are to be necessary for creating the next-generation semiconductor devices with ultra-fine structures. Final goal of this research is to clear the reaction mechanisms of electron-beam-induced excitation of a Si_2H_6/Si (001) system and apply this electron-beam irradiation method to atomic-scale crystal growth. The head investigator has already indicated the possibility of atomic-scale crystal growth with this system from his early research.In the first stage of this research, the reaction mechanisms of thermal excitation were investigated, which provide fundamental processes necessary for exploring of a new crystal growth technique. As a result, relations between adsorption reaction, pyrolysis reaction of adsorbates, surface migration reaction of adsorbates, and epitaxial growth reaction have been clearly understood in the wide range of growth temperature and Si_2H_6 pressure. T … More hese results should give important and fundamental knowledge to understand the surface reaction mechanisms of IV group semiconductors and to expand crystal growth technologies.On the basis of this research, a sub-monolayr-by-sub-monolayr digital epitaxial growth technique of Si has been proposed, and multilayr Si films have been successfully grown with this technique. This technique is named Sub-Atomic-Layr Epitaxy. The results has been published in international conferences of IUMRS (Tokyo, 1993) and so on.Through the above research, relations between desorption mechanism of hydrogen, surface adatom migration mechanisms, and epitaxial growth mechanisms have been well understood. These mechanisms suggest the direction of coming research on atomic-scale digital epitaxy.In the final stage of this research, electron-induced desorption of hydrogen from Si_2H_6・adsorbed Si surfaces was tried on the basis of the above knowledge. The hydrogen desorption is a key process for atomic-scale digital epitaxy. To accomplish the experiment, a new system has been successfully constructed where both of electron-beam and Si_2H_6 gas are able to be simultaneously introduced on the surface. With this system, the promotion of Si growth and hydrogen desorption by the electron-beam irradiation has been confirmed. This research indicates a clue to apply the surface excitation method by electron-beam irradiation to next epitaxial growth technologies. Less