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形成非晶硅薄膜的早期过程中，SiH_4分子的电子碰撞解离过程起着重要的作用。研究具有一定能量的一个电子与一个SiH_4分子的单碰撞过程是最基础、最重要的知识之一。在本工作中，测量了从阈值到1000 eV的能量范围内电子碰撞从SiH4中分裂出来的激发碎片的发射截面。目前还没有关于SiH_4真空紫外区发射截面测量的其他报道。下面我们总结一下所获得的结果。不仅在可见光区，而且在真空紫外区对H、Si、Si^+、SiH等碎片物种进行了详细的光谱指认。2.测量了上述各组分的绝对发射截面。3.电子束的能量覆盖范围很广，从阈值到1000 eV。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的工作有很大的不同。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.研究发现，SiH_4分子的对称性禁忌态在产生激发态氢原子中起着重要的作用。

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.