Dust Growth Instabilities in Silane-based Plasmas

In this paper we report on two instabilities observed in dusty plasmas, at different stages of dust particle formation. Experiments are performed in a low-pressure Ar/SiH4 radiofrequency plasma. The first instability, occuring at the transition between nanocrystal accumulation and coalescence phases, is very sensitive to operating conditions. It is shown to be a good indicator of the end of nanocrystal accumulation phase in the plasma. This “coalescence instability” seems to be an attachment induced-ionization instability as observed in electronegative gases. The second instability starts during the second dust generation formation. It exhibits a complex scheme closely linked to dust successive generations. This instability is suspected to be a void instability. Indeed, the occurence of this “successive generation instability”, combined with laser light scattering and Ar*(750.38 nm) line spectroscopic measurements indicate a possible void region in the dust cloud, as observed in PKE experiments.