Studies of Surface Reaction on Solids by Using Suprathenal Beams.

(1)研究了Si与C_2H_2分子束反应在Si(001)表面形成β-SiC膜的生长机理。薄膜是在1000K以上的表面温度下形成的。在表面反应受小束流限制的条件下，薄膜外延生长。但在束流密度过大的情况下，由于在表面形成富碳层，导致薄膜生长速率下降，并在薄膜中观察到许多丘状结构。(2)用脉冲分子束技术研究了在1000~1300K温度范围内，SiO_2与Si(100)和(111)表面反应的脱附动力学。在低于1050K的温度下，氧束辐照表面后，SiO信号出现一段诱导时间，这意味着脱附是通过连续的步骤进行的。通过对…的计算机模拟，得到了两步反应的速率常数为了研究紫外光照射下固体表面与碰撞分子之间的相互作用，我们用质谱仪检测了激光照射固体表面后产生的分子，并用飞行时间法测定了它们的动能。我们注意到，在这个过程中产生了具有少量电子伏安的高能分子。(4)用脉冲低能(500)Ne~+束轰击吸水的Si(100)表面。对于具有不同水覆盖的表面，测量了中性物加正离子或只有中性物的飞行时间光谱。通过比较这两种光谱，研究了散射Ne原子和反冲O原子的正离子分数与水吸附的关系。结果表明，随着盖度的增加，Ne^+和O^+组分的变化趋势相反，Ne^+组分随盖度的增加而减少，而O^+组分随盖度的增加而增加。较少

(1) We studied the growth mechanism of beta-Sic film formation on Si (001) surface by reaction of Si with C_2H_2 molecular beams. The film was formed above the surface temperature of 1000K. Under the condition that the surface reaction was limited by the small beam flux, the film grew epitaxially. But, under the condition that the beam flux was too large for the reactive Si atoms on the surface, the film growth rate decreased due to formation of the carbon rich layer on the surface, and many hillocks were observed in the grown film.(2) Desorption kinetics of SiO in the reaction of O_2 with Si (100) and (111) surfaces were investigated at surface temperatures between 1000 and 1300K by using a pulsed molecular beam technique. At lower temperatures than 1050K, the SiO signal appeared with an induction time after the O_2 beam irradiation onto the surface, which means that desorption occurs via sequential steps. The rate constants for two steps were obtained by a computer simulation of the … More relaxation waveforms of the SiO signal.(3) In order to study the interaction between the solid surface irradiated by ultra violet laser and the colliding molecules, we detected the outcoming molecules from the surface after the laser irradiation by a mass spectrometer and determined their kinetic energies by a time-of-flight method. We noticed that the energetic molecules having a few eV were produced in the process. The mechanism is now under the investigation.(4) Water-absorbed Si (100) surface were bombarded by a pulsed low energy (500) Ne^+ beam. Time-of-flight spectra for neutrals plus positive ions or neutrals only were measured for the surface with various water coverages. By comparing the two kinds of spectra, the dependence of positive ion fractions of scattered Ne and recoiled O atoms upon water adsorption was studied. It was found that the Ne^+ and O^+ fraction changes in an opposite way depending on the water coverage such that the Ne^+ fraction decreases with increasing the coverage, whereas the O^+ fraction increases with it. Less