Synthesis of carbon nanotubes by plasma-enhanced chemical vapor deposition in an atmospheric-pressure microwave torch

Abstract

Abstract:There are many different techniques for the synthesis of carbon nanotubes (CNTs), and plasma technologies experience a significant competitor in thermal chemical vapor deposition (CVD) processes. A particular process is, therefore, selected according to the specific requirements of an application, which clearly differ for the development of composites as compared to nanoelectronics, field emission, displays, sensors, and the like. This paper discusses the method for the synthesis of CNTs using an atmospheric-pressure microwave (MW) torch. It was successfully applied in the fast deposition of multiwalled nanotubes (MWNTs) on a substrate without the necessity of any vacuum or heating equipment. Dense straight-standing nanotubes were prepared on Si substrates with and also without barrier SiO x layer. Therefore, it was possible to produce CNTs directly on conductive Si and to use them as an electron-emitting electrode of the gas pressure sensor. The CNTs grown in MW torch were also used to create a gas sensor based on the changes of electrical resistance measured between two planar electrodes connected by the CNTs.

Sensing Properties of Multiwalled Carbon Nanotubes Grown in MW Plasma Torch: Electronic and Electrochemical Behavior, Gas Sensing, Field Emission, IR Absorption

“…A fast growth of VA-MWCNT films on the c-Si and c-Si/SiO 2 substrates has been achieved in MW plasma torch operated at atmospheric pressure without an external heating source [ 44 , 45 ]. The characterization of the VA-MWCNT films by SEM, transmission electron microscopy (TEM), Raman spectroscopy and the influence of process parameters on the CNT growth were discussed in detail in our previous publications [ 3 , 46 , 47 ]. Typical SEM images of prepared VA-MWCNT film are shown in Figure 2 .…”

“…In thermal CVD, a carbon-containing gas mixture is heated typically to 550–1100 °C by a conventional heat source. Plasma enhanced CVD (PECVD) activates the gas mixture by ignition of plasma discharge but a separate heating of the substrate might be required too [ 3 ]. General arguments for the PECVD include low-temperature, easily achieved vertical alignment and large area processing [ 4 ].The CVD methods are used for a CNT volume-synthesis and a surface-bound growth of vertically aligned and micropatterned CNT arrays [ 5 ].…”

“…, using the MW plasma torch [ 48 ]. Another advantage is a successful preparation of vertically aligned MWCNTs directly on Si without using a barrier SiO 2 layer [ 3 ]. A direct contact between the VA-CNTs and the Si substrate can be very important for some applications and it enables the construction of a field-emission based pressure sensor [ 49 ].…”

Carbon composite micro- and nano-tubes-based electrodes for detection of nucleic acids

“…( A ) Set-up of the apparatus for PECVD MWCNTs direct deposition (according to [8]). ( B ) Surface-enhanced micrographs of the electrodes fabricated on the Ag-based thick film paste (1) without and (2) with use of 10 nm Fe catalyst (Tescan, Czech Republic).…”

“…The reproducible nanostructured electrode surface could be fabricated using lithography as a common tool for microelectronics devices implementation [5], anodization process for nanorods or nanotubes creation [6,7]. One of these techniques is the creation of vertically aligned multiwalled carbon nanotubes (MWCNTs) grown directly on the surface using chemical vapour deposition (CVD) [8]. The aim of this study was to fabricate MWCNTs and further to test the particles as a part of carbon composite electrodes with commercial carbon particles on detection of nucleic acids.…”