We presented an in-flight microplasma synthesis of luminescent Si-NCs between 3 nm and 5 nm: Si-NCs were continuously synthesized at room temperature in the sense that high temperature post-annealing is not necessary. Based on the microplasma properties estimated by OES, a-Si nanoparticles nucleate initially in the post-plasma region; therefore, particle crystallization is independent of gas temperature as well as electron density. Subsequently, a-Si nanoparticles were crystallized if sufficient amount of input power or hydrogen was applied: atomic hydrogen recombination on nanoparticle should play a major role in crystallization of silicon nanoparticles. Strong red-photoluminescence due to quantum confinement effect was observed from Si-NCs after 24 hour natural oxidation. The given microplasma reactor provides simple and viable production method of silicon nanoparticles at a mass production rate of more than 30 mg/h. For the next challenge, size-dependent luminescent tunability of as-produced material is being optimized with respect to operating pressure, reaction time, and SiCU partial pressure.
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