SYNTHESIS OF CARBON NANOSTRUCTURES BY PLASMA ENHANCED CHEMICAL VAPOUR DEPOSITION AT ATMOSPHERIC PRESSURE

Carbon nanostructures present leading field in nanotechnology research. Wide range of chemical and physical methods was used for carbon nanostructures synthesis including arc discharges, laser ablation and chemical vapour deposition. Plasma enhanced chemical vapour deposition (PECVD) with its application in modern microelectronics industry became soon target of research in carbon nanostructures synthesis. The selection of the ideal growth process depends on the application. Most of PECVD techniques work at low pressure requiring vacuum systems. However for industrial applications it would be desirable to work at atmospheric pressure. In this article carbon nanostructures synthesis by plasma discharges working at atmospheric pressure will be reviewed. Special attention will be given to microwave discharges and atmospheric pressure glow discharge (APG). Our group has successfully synthesized multi-walled carbon nanotubes directly on substrate or in volume by microwave plasma torch. We were able to growth several tens of micrometers high layer of nanotubes in time less than 1 minute, without any external heating source. The carbon nanotubes layer could be also grown on substrates without a buffer layer or with predefined patterns. Lately APG discharge became an attractive method to growth single-walled carbon nanotubes with good alignment. Critical factor for growth of carbon nanotubes is the catalyst. Properties of buffer layer between substrate and catalyst and catalytic particles size considerably influence final product and are key to control of nanotube properties and growth conditions such as temperature and gas mixture. In the end of the article a possibility to synthesize graphene with atmospheric pressure discharges is discussed