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

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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.