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

1.Si（100）表面态的光电子强度在Si生长过程中周期性振荡，这种振荡与2xl和lx2表面重构的交替有关。振荡的起源是在2xl和lx2清洁表面之间的表面波段色散的差异。气源分子束外延（GSMBE）淬火后，硅烷对Si（100）表面脱氢的反应阶数为1.59，而二硅烷的反应阶数为1。进行了一阶和二阶解吸动力学的模型计算，成功地再现了中间反应级数。干氧在Si（100）表面的初始热氧化过程中，存在两种生长模式，在650℃左右的临界温度下，两种生长模式发生切换：低温区为langmuir型吸附模式，高温区为2D岛生长模式。Si（100）表面磷通过抑制氢缔合和增加解吸能来限制氢的脱附，从而导致gsmbe过程中Si的生长速率下降。硅烷在Si（100）表面的吸附很可能在600℃附近发生变化，随着吸附温度的升高，硅烷在Si（100）表面的吸附模式从低于该温度的两点吸附转变为四点吸附。从SiH_3吸附前体的可能存在及其从表面的热活化解吸出发，对硅烷吸附的这种温度依赖性行为给出了统一的解释。干燥氧在Si（100）清洁表面进行初始热氧化时，Si （2p）核心能级光谱中的Si^<4+>组分在氧化开始后立即出现。这表明SiO_2层是在表面局部形成的。

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.