Preparation of SiOC nanocomposite films by laser chemical vapor deposition

Silicon oxycarbide (SiOC) composite films were prepared by laser chemical vapor deposition (LCVD) under various conditions using tetraethyl orthosilicate (TEOS) as precursor. X-ray diffraction, Fourier transform infrared and X-ray photoelectron spectroscopy data suggest that β-SiC nano-crystals form in the films at deposition temperatures above 1674 K, with SiOC films forming below 1674 K and Si crystals appearing at 1775 K. Composite films containing both SiOC and SiC formed through Si-O bond breaking, the polymerization of silane oligomers, and the subsequent pyrolysis of TEOS during the LCVD process. The appearance of Si at higher temperatures is attributed to the decomposition of SiO and/or to the further oxidation of SiC. The β-SiC nano-crystals in the film are characterized by crystalline SiC cores 100-200 nm in diameter and amorphous SiOC shells 20-30 nm thick.