EVIDENCE FOR FREE CARBON IN AMORPHOUS OMCVD SILICON-RICH Si_xC_1-x COATINGS

Abstract

Silicon-rich SixC1-x layers have been deposited by OMCVD at low pressure in the temperature range 800-1000°C using the organometallic compound SiEt4 for both Si and C source. A Si enrichment of these amorphous SixC1-x coatings was obtained by addition of SiH4 to the gas-phase. The influence of this silane partial pressure increase on the growth rate, the composition and optical properties of the films has been investigated. In spite of the silicon excess, evidence for free carbon was found both in the variation of the optical band gap and the IR spectra. The XPS (X-ray Photoelectron Spectroscopy) analysis argues also for a heterogeneous microstructure for these amorphous ceramic thin films

Mechanical properties of SiC/SiC composites with a treatment of the fiber/matrix interfaces by metal-organic chemical vapor co-deposition of C and SixC1-x

“…The tetraethylsilane SiEt4 is a suitable organometallic precursor for the deposition of SiXCl-, between 700 and 900 "C [ll]. In this temperature domain, a wide range of composition is possible using addition in the gas phase of either SiH4 or cumene iFrCgHg for Si [12] or C [9] enrichment, respectively. For this study, C-rich SiXC1-, interlayers have been deposited on the Sic fibers by the simultaneous pyrolysis of SiEQ and cumene.…”