Study on the primary dissociation processes of monosilane molecule by electron impact

一般认为，在辉光放电等离子体中，SiH_4分子的电子碰撞解离过程在非晶硅薄膜形成的早期阶段起着重要的作用。研究具有一定能量的单电子与SiH_4分子的单次碰撞过程中发生了什么是最基本、最重要的知识之一。本文测量了SiH_4在电子碰撞作用下，在阈值至1000 eV能量范围内，激发态碎片的发射截面。关于SiH_4真空紫外区发射截面的测量，目前还未见报道。在下文中，我们总结了所获得的结果。1.对H，Si，Si^+，SiH等碎片物种的光谱进行了详细的归属，不仅在可见光区，而且在真空紫外区。2.测量了上述物种的绝对发射截面。3.电子束的能量覆盖了从阈值到1000 eV的宽范围。4.详细测量和讨论了激发函数的精细结构。特别是SiH（A-X）在20 eV附近的截面特征与以前报道的工作有很大不同。5.用统计分布的思想解释了激发态氢原子的发射强度与主量子数n的关系。6.发现SiH_4分子的对称性禁戒态对激发态H原子的产生起着重要的作用。

It is generally said that the dissociation process of SiH_4 molecule by electron impact plays an important role in the early steps of building up thin film of amorphous silicon in glow discharge plasmas. It is one of the most fundamental and important knowledge to investigate what happen in the single collision between one electron with definite energy and one SiH_4 molecule. In the present work, the emission cross sections for excited fragments split from SiH_4 by electron impact were measured in the energy range from the threshold to 1000 eV. There is no other report on the measurement of the emission cross sections in the vacuum ultra-violet region for SiH_4. In the following we summarize the results obtained.1. A detailed spectroscopic assignment for fragment species such as H, si, Si^+, SiH were carried out not only in the visible but also in the vacuum ultraviolet regions. 2. The absolute emission cross sections were measured for those species mentioned above. 3. The energy of electron beam covers a wide range from the threshold up to 1000 eV. 4. The fine structure of the excitation functions were measured and discussed in detail. Especially, the feature of the cross sections for SiH (A-X) around 20 eV differs markedly from the works reported before. 5. The dependence of the emission intensities of the excited hydrogen atom on the principal quantum number n is explained by the idea of the statistical distribution. 6. It was found that the symmetry forbidden states of SiH_4 molecule play a considerable role in producing excited H atoms.