Development of time-dependent vibration-excited spectroscopy and study on the growth process of semiconductor thin films.

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We have developed a time dependent measurement method of vibration-excited spectroscopy for elucidating an in-situ dynamical observation of surface reaction at the gas-solid interface and studied the hydrogen adsorption process on Si(100) surfaces. Main results obtained in this study are as follows:1. It has been made a vibration-excited spectroscopic apparatus to be able to measure time-series signals. This system has an energy resolution of 7 meV, a signal stability of better than 1.6% and a maximum elastic peak count rate of 1-2x10^5 cps. It can be performed by this system to observe the vibration of substrate surface atoms and adsorbed atoms in high sensitivity and to apply to measurements of the time dependent signals.2. It has been measured a vibrational mode of Si(100)-2x1 clean surfaces. We can observe an energy loss peak of 100 meV, which is concluded to result from a dimer structure of Si(100)-2x1 with a displacement component in the surface normal direction, an A_1 mode.3. I … More n the atomic and molecular hydrogen adsorption on Si(100)-2x1, Si-H monohydride bonds are formed in the initial stage of adsorption and the vibration signals of Si-2H dihydride bonds increase with increasing exposure. After annealing of a hydrogen saturated surface at 420ﾟC, Si-2H bonds change to Si-H bonds.4. It can be found that the clean surface of Si(100)-2x1 produced by high temperature annealing in an ultra high vacuum is inactive for oxidation at room temperature. The adsorption site of oxygen atoms in the initial stage of oxidation is a bridge bond of the dimer Si atoms, and the oxidation proceeds with the adsorption of oxygen atoms at the site between the first and second Si layers.5. It has been successful to perform the time-dependent measurements of an atomic hydrogen adsorption process on Si(100)-2x1. Peak intensities of vibration signals of the clean surface with 100 meV and the Si-H bonds with 79 meV are found to change exponentially with the exposure time. The decay factor and the hydrogen adsorption rate factor in each signal are 1.4x10^<-4> and 3.6x10^<-4> /sec, respectively. The surface diffusion coefficient of hydrogen atoms obtained these values is about 10^<-20> cm^2/sec, which is much smaller than that for metal surfaces. Less