In-flight Microplasma Synthesis of Luminescent Silicon Quantum Dots in Macroscopic Quantities

Abstract

In-flight microplasma synthesis of luminescent silicon nanocrystals (Si-NCs) is presented. A mixture of SiCl4 and H2 is activated in the high pressure (10 kPa), miniaturized (200 μl) non-thermal plasma reactor. High pressure condition accelerates cluster nucleation via three-body reaction, while a miniaturized reactor suppresses excess crystal growth due to short residence time, leading to 3−5 nm crystalline nanoparticles: process yield of 30−100 mg/h of luminescent Si-NCs was demonstrated. Crystallinity of as-produced silicon nanoparticles increased with increasing either input power or initial H2 content in the feed gas. Strong photon absorption in the short wavelength (less than 450 nm) and associated red-photoluminescence due to quantum confinement effect was confirmed.