Growth of Carbon Nanotubes at Low Powers by Impedance-Matched Microwave Plasma Enhanced Chemical Vapor Deposition Method

Abstract

A solo carbon nanotube (CNT) was successfully grown on nickel electrodes by a microwave plasma enhanced chemical vapor deposition (MPECVD) method equipped with an impedance-matched substrate holder with the reaction gases composed of hydrogen (H2), carbon dioxide (CO2), and methane (CH4) mixtures. An introduction of carbon dioxide gas before CNTs growth, the substrate temperature can easily be reached above 610 degrees C even heated at a low microwave power. This can be enunciated from fact that carbon dioxide inherits with higher bond energy for molecular dissociation, lower thermal conductivity, and higher heat capacity in comparing to other gases. The electron field emissions for randomly aligned CNTs and well-aligned CNTs grown by MPECVD and by radio frequency assisted hot-filament methods, respectively, are measured and compared. The higher field emission characteristic of the randomly aligned CNTs is presumed to be due to the protruded CNTs, which inheriting with less screening effect and manifesting with defects are crucial to play the effective emission sites.

The Infinite Possible Growth Ambients that Support Single-Wall Carbon Nanotube Forest Growth

“…thermal CVD, plasma-enhanced CVD, floating catalyst CVD, laser ablation, seemed to show preferences on the carbon feedstock 22,23,24 . For example, in plasma-enhanced CVD, methane or other low molecular-weight carbon feedstocks are preferred 22 , while for floating catalyst CVD, which is carried out at higher temperatures, cyclic aromatic hydrocarbons, e.g. toluene, xylene and benzene are most commonly used due to their high decomposition temperatures 23,24 .…”

CO2-Assisted SWNT Growth on Porous Catalysts

“…To confirm this hypothesis and find a way to increase the SWNT yield, CO 2 was introduced into the SWNT synthesis system that used a Fe/Mo/MgO model catalyst to decompose methane. Conventionally, CO 2 has been used in the synthesis , and postprocessing of CNTs. − The effects of CO 2 observed in previous works include the regeneration of the catalysts, help in giving more uniform SWNT samples, and thinning and opening of the ends of the tubes, which are similar effects to oxygen or water on the growth of CNTs. , However, in the present work, in addition to looking at the previous effects of the presence of small amounts of CO 2 on the purity of the SWNT products, the effects on the catalyst support and the catalyst texture were also examined. It is well-known that CO 2 can interact with MgO to form MgCO 3 species.…”

Model analysis of temperature dependence of abnormal resistivity of a multiwalled carbon nanotube interconnection

“…The scanning electron microscopic image of a multiwalled carbon nanotube which was grown at 650°c and 10 −5 torr with a 3 µm length and 100 nm diameter between two isolated electrodes as a current conduction bridge. 4,16 B) A cross-sectional image of another sample of the same batch of multiwalled carbon nanotubes.…”

“…This particular MWCNT was fabricated using a homemade microwave plasma-enhanced chemical vapor deposition (MPECVD) system. 4,16 In order to explain the result of a negative TCR, we took into account the theories of hopping conductivity, variable range hopping conductivity, strong localization (k f l 0 ∼ 1, in the product k f l 0 , where k f is the quasi-Fermi wave vector, l 0 is a finite mean free path, and reflects the degree of the disorder and localization) and grain boundary scattering. 17…”

“…In this study, for the purpose of modeling an analysis of the temperature dependence of resistivity, a MWCNT was fabricated as an interconnector by the MPECVD method. 4,16 Catalyst nickel electrodes were deposited onto a SiO 2 layer which was grown on a silicon wafer by the traditional thermal oxidation system to prevent current leakage from the MWCNT device. The gap between the electrodes was approximately 5-10 µm and benefited from the wet etching process.…”