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薄膜的生长机理。薄膜在表面温度为1000K以上形成。在小束流限制表面反应的条件下，薄膜呈外延生长。但在束通量过大的情况下，由于表面的反应性Si原子形成了富碳层，膜的生长速率下降，生长的膜中出现了许多丘状结构。(2)采用脉冲分子束技术研究了表面温度在1000 ~ 1300K范围内O_2与Si（100）和Si（111）表面反应中SiO的脱附动力学。在低于1050K的温度下，O_2光束照射到表面后，SiO信号随感应时间的延长而出现，说明脱附过程是连续的。通过对SiO信号的弛豫波形的计算机模拟，得到了两步的速率常数。(3)为了研究紫外激光照射固体表面与碰撞分子之间的相互作用，用质谱仪检测了激光照射后固体表面出射的分子，并用飞行时间法测定了分子的动能。我们注意到在这个过程中产生了具有几个电子伏特的高能分子。该机制目前正在调查中。(4)用低能量（500）Ne^+脉冲束轰击吸水Si（100）表面。在不同水覆盖的表面上测量了中性离子加正离子或仅中性离子的飞行时间谱。通过对两种光谱的比较，研究了散射态Ne原子和反冲态O原子正离子组分对水吸附的影响。结果表明，Ne^+和O^+分数随水覆盖的增加呈相反的变化规律，Ne^+分数随水覆盖的增加而减少，而O^+分数则随水覆盖的增加而增加。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