The Study of Synchrotron-Radiation-Stimulated Surface Chemical Reactiions on Semiconductors by Surface Electron Spectroscopy

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1.The photoelectron intensities from the surface states on Si (100) periodically oscillate during Si growth and the oscillation is associated with the alternation between the 2xl and lx2 surface reconstructions. The origin of the oscillation is the difference in the surface band dispersions between the 2xl and the lx2 clean surfaces.2.The hydrogen-desorption process from Si (100) surfaces quenched from gas-source molecular-beam epitaxy (GSMBE) using silane has a reaction order of 1.59 in contract with the process using disilane having a reaction order of 1. A model calculation involving both first-and second-order desorption kinetics is performed, which successfully reproduced the intermediate reaction order.3.For initial thermal oxidation on Si (100) by dry oxygen, there exist two growth modes, whose domination switches at a critical temperature around 650ﾟC : Langmuir-type adsorption mode in the lower temperature region and 2D island growth mode in the figher temperature region.4.Surface phosphorus on Si (100) restrics hydrogen desorption both by suppressing hydrogen association and by increasing the desorption energy, which lead to a decline of the Si growth rate during GSMBE.5.Silane adsorption on Si (100) most probably changes its mode near 600ﾟC,from two-site adsorption below this temperature to four-site adsoeption as the adsorption temperature is increased. A unified interpretation is given for this temperature-dependent behavior of silane adsorption, from the possible presence of a SiH_3 adsorption precursor and its thermally activated desorption from the surface.6.For initial thermal oxidation on Si (100) clean surface by dry oxygen, Si^<4+> component in Si 2p core level spectra immediately appears after the onset of the oxidation. This indicates that the SiO_2 layr is locally formed on the surface.