Particle production in high density silane plasma

To understand the mechanisms of nanoparticle formation and its potential applications, we have investigated silicon particles formed in various gasses in an inductive coupled plasma (ICP) system and have measured their structural properties by electron microscopy. Particle generation in pure SiH₄ and SiH₄/H₂ are reported. ICP silane plasmas are shown to be an interesting and versatile source of nanoparticles. Three regimes are mapped out: a regime of no observable particle growth at the lowest pressures, a regime of polydisperse and agglomerated particles at the highest pressures, and a regime yielding highly monodisperse particles at intermediate pressures. Conditions that generate these nonagglomerated, extremely monodisperse silicon particles are emphasized. For H₂ dilutions less than 92%, the growth rate is almost independent of H₂ partial pressure. Particle growth decreases steadily when the H₂ dilution is increased further. TEM images, however, indicate that the addition of hydrogen decreases the particle density. At higher dilution ratios, polycrystalline particles are obtained. Under all other conditions the particles are amorphous. Reasons for this behavior are explored.