Carbon nanotubes overgrown and ingrown with nanocrystalline diamond deposited by different CVD plasma systems

Abstract

In this work we investigate the growth of diamond film on a porous single-wall carbon nanotubes (SWNT) paper by employing three different Chemical Vapour Deposition (CVD) systems: plasma-assisted hot filament, focused microwave plasma and linear antenna microwave plasma. We observe that the diamond growth is strongly affected by the different conditions in each of the CVD processes resulting in different SWNT/diamond composite structures. It is also found that only the linear antenna microwave plasma CVD process allows penetration of the activated growth species into the volume of the SWNT paper, whereas using the other methods, the diamond grains are formed on the SWNT paper surface only. Moreover, the growth of diamond structures within the substrate volume is strongly influenced by the CH 4 /CO 2 /H 2 gas content ratio. A key factor influencing the formation of a compact SWNT/diamond composite is keeping the equilibrium between two competitive processes: establishing conditions where the diamond structure can grow while etching/damage of the SWNT paper is still kept at a minimum. The morphology and chemical composition of formed composite materials were characterized by scanning electron microscopy and Raman spectroscopy.

Quartz crystal microbalance gas sensor with nanocrystalline diamond sensitive layer

“…Further, it is visible that the diamond films morphology also agrees well with the presented Raman spectra. In both Raman spectra, there are three characteristic features: the peak located at 1332 cm À1 is well known as a diamond peak and is related to sp 3 bonds, D-band at $1360 cm À1 related to a small graphite crystallites and finally G-band at $1620 cm À1 [14]. Such a fairly high signal from sp 2 phases in the Raman spectra is observed due to a slow etching of sp 2 -bonded carbon by atomic hydrogen/oxygen during the deposition and it results in the deposition of ultra-or nanocrystalline diamond.…”

Great Variety of Man-Made Porous Diamond Structures: Pulsed Microwave Cold Plasma System with a Linear Antenna Arrangement

“…Using the bottom-up approach, porosity of the diamond films is achieved by either (i) employing geometrically prestructured substrates (i.e., templated growth) or (ii) optimized chemical vapor deposition (CVD) by providing suitable growth conditions (mainly by varying the gas mixture). The variety of supporting substrates includes fully or partially transformable polymers, 19−21 various non-carbon-based templates, 14,17,22,23 carbon-based templates, 24−28 or SiO x -based templates. 29−31 The important advantage of templated diamond growth is that the porosity is generally guided by the template that is used.…”

“…Using the bottom-up approach, porosity of the diamond films is achieved by either (i) employing geometrically prestructured substrates (i.e., templated growth) or (ii) optimized chemical vapor deposition (CVD) by providing suitable growth conditions (mainly by varying the gas mixture). The variety of supporting substrates includes fully or partially transformable polymers, − various non-carbon-based templates, ,,, carbon-based templates, − or SiO x -based templates. − The important advantage of templated diamond growth is that the porosity is generally guided by the template that is used. ,, In the course of the development and usage of these supports, various aspects of procedures that can be used and specific applications have already been discussed. For example, diamond nanoparticles in a polymer matrix can be used for fabricating porous diamond structures, , for enhancing the seeding efficiency in planar diamond deposition and for diamond growth on vertical structures. ,, In the case of diamond deposition on graphitelike materials, the proper seeding technology and the chemical stability of these materials has a direct effect on the final geometry of the structure that is formed. , In addition, the pore size of the templates has a strong influence on the penetration of the growth species in depth (i.e., in the Z -direction) during chemical vapor deposition (CVD).…”