Powder evolution at low powers in silane-argon discharge

Powder formation in a 13.56-MHz radio frequency (rf) capacitive glow discharge plasma of silane-argon mixture has been studied by in situ laser light-scattering measurements. The rf power density (Prf) was varied from 18 to 53 mW/cm2. At high Prf the light scattering occurs all along the discharge and extends even beyond the exit end of the electrodes toward the pumping system. With decreasing Prf the maximum intensity of the light scattering decreases and the scattering zone shrinks and moves toward the exit end. With Prf≅20 mW/cm2 a very bright scattering zone only a few centimeters wide appears located at the electrodes outlet. The powders studied by transmission electron microscopy did not show a drastic decrease of their sizes with Prf though clear coagulation of small particles is observed at high Prf. In this paper we have tried to link the laser light-scattering evolution with Prf to various parameters such as the microstructure factor, the deposition rate, the electron mobilityxlifetime product, the density of states, and the minority-carriers diffusion length of the films in an attempt to link the effect the evolution of powder formation to the films properties