Nanometric powder of stoichiometric silicon carbide produced in square-wave modulated RF glow discharges

SiC nanometric powder has been obtained in square-wave modulated radiofrequ ency glow discharges from CH4 and SiH4 gas mixtures. Chemical and structura l characterization revealed that the as-deposited SIC:H powder underwent sp ontaneous oxidation when exposed to atmosphere. To stabilise the powder che mically, we carried out a thermal treatment under vacuum (10(-4) Pa) consis ting of healing to 800 degrees C (20 degrees C/min). The effects on the str ucture of the powder were examined by FTIR, EA, XPS and from optical transm ittance measurements. They can be summarized as follows: dehydrogenation of the powder that induces the formation of a SIC carbidic network and chemic al stability under atmospheric conditions, further confirmed by exposure to air for more than 6 months. In addition, TEM images showed that the anneal ed powder presented a short-range order in beta-SiC units, but there was no evidence of size changes due to sinterization or compactaction phenomena. (C) 1998 Elsevier Science Ltd. All rights reserved.