SiC nanocrystals: high-rate deposition and nano-scale control by thermal plasma

This work used thermal plasma to enhance the deposition process of SiC nanocrystals, with SiCl4 and CH4 as the Si source and C source, respectively. Thin films containing SiC nanocrystals, a-Si and graphite were deposited on the substrates. The morphology and crystalline structure of the samples were characterized by various techniques, including SEM, TEM, and XRD. SiC nanocrystals were observed being covered by carbon films and embedded in the network formed by graphite and a-Si. The effect of SiCl4 input rate on the deposition process and product properties was studied in detail, combining characterization techniques and optical emission spectroscopy (OES) diagnostic results. Based on the OES diagnostic of the plasma zone, the concentrations of atomic Si and C in the gas phase are concluded to be the main factors affecting the deposition process. Finally, a simple deposition mechanism is deduced based on the experimental results, which indicates the formation of SiC nanocrystals through the assembly of atomic species in the plasma.