Numerical investigation of particle formation mechanisms in silane discharges.

The formation of particles in low-pressure silane discharges has been studied extensively over the last decade. In this paper we try to identify, by numerical simulations, the precursors of the dust formation and we examine the gas-phase reactions leading to larger clusters, and finally to nanometer or micrometer sized particles. A one-dimensional fluid model is used, which incorporates silicon hydrides (Si(n)H(m)) containing up to 12 silicon atoms. A set of 68 species, including neutrals, radicals, ions, and electrons, is taken into account. The importance of various cluster reaction sequences is discussed. Besides the discussion of ion-molecule and ion-ion reactions, the role of the vibrationally excited silane molecules and of SiH3 radicals on the particle growth process is studied. Finally, the effect of temperature variation on the density of the dust particles is investigated.