Observation of dust particle growth and fallout in RF-excited silane discharges

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Abstract
Particles formed during plasma enhanced chemical vapor deposition of amorphous silicon thin films which fall to the film surface, either during or after the process, may have a severely deleterious effect on film properties. In order to understand the mechanisms of particle formation and fallout we have investigated the growth and dynamics of particles in RF discharges in pure silane. The diameter of particles formed within the first 20 s of the discharge was investigated by electron microscopy of substrates with fallen out particles. Furthermore we used a He-Ne laser in combination with a diode array camera to measure temporally and spatially resolved light scattering from particles and deduced their sinking speed after switching off the discharge. The results are compared to a theoretical model on the particle dynamics.