Effects of Feed Gas Composition and Catalyst Thickness on Carbon Nanotube and Nanofiber Synthesis by Plasma Enhanced Chemical Vapor Deposition

2008 ◽  
Vol 8 (6) ◽  
pp. 3068-3076 ◽  
Author(s):  
R. K. Garg ◽  
S. S. Kim ◽  
D. B. Hash ◽  
J. P. Gore ◽  
T. S. Fisher
Keyword(s):  
Carbon Nanotubes ◽  
Phase Composition ◽  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Computational Study ◽  
Chemical Vapor ◽  
Gas Composition ◽  
Hydrogen Mixture

Many engineering applications require carbon nanotubes with specific characteristics such as wall structure, chirality and alignment. However, precise control of nanotube properties grown to application specifications remains a significant challenge. Plasma-enhanced chemical vapor deposition (PECVD) offers a variety of advantages in the synthesis of carbon nanotubes in that several important synthesis parameters can be controlled independently. This paper reports an experimental study of the effects of reacting gas composition (percentage methane in hydrogen) and catalyst film thickness on carbon nanotube (CNT) growth and a computational study of gas-phase composition for the inlet conditions of experimentally observed carbon nanotube growth using different chemical reaction mechanisms. The simulations seek to explain the observed effects of reacting gas composition and to identify the precursors for CNT formation. The experimental results indicate that gas-phase composition significantly affects the synthesized material, which is shown to be randomly aligned nanotube and nanofiber mats for relatively methane-rich inlet gas mixtures and non-tubular carbon for methane-lean incoming mixtures. The simulation results suggest that inlet methane-hydrogen mixture coverts to an acetylene-methane-hydrogen mixture with minor amounts of ethylene, hydrogen atom, and methyl radical. Acetylene appears to be the indicator species for solid carbon formation. The simulations also show that inlet methane-hydrogen mixture does not produce enough gas-phase precursors needed to form quality CNTs below 5% CH4 concentrations in the inlet stream.

Chemical vapor deposition of nickel-group metals on multiwall carbon nanotubes

2007 ◽  
Vol 85 (10) ◽  
pp. 645-650 ◽  
Author(s):  
Maoqi Feng ◽  
Richard J Puddephatt
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Multiwall Carbon Nanotubes ◽  
Chemical Vapor ◽  
Pt Films ◽  
Bimetallic Films ◽  
Multiwall Carbon

Chemical vapor deposition (CVD) of Ni, Pd, and Pt films and of Ni/Pd and Pd/Pt bimetallic films on multiwall carbon nanotubes (MWCNTs) can be effected at low temperature if the nanotubes are pretreated by CVD of titanium carbide. In the absence of the pretreatment, the CVD leads to formation of isolated nanoparticles of the nickel-group metals. The metallized MWCNTs are curved or kinked, as a result of the interaction with the metal. Preliminary oxidation of the carbon nanotubes allows easier metallization, and the bending of the metallated nanotubes is not observed in this case.Key words: Chemical vapor deposition, platinum, palladium, nickel, carbon, nanotube.

Synthesis of Controllably Grown Carbon Nanotubes Interconnects

2007 ◽  
Vol 1018 ◽  
Author(s):  
Seon Woo Lee ◽  
David Katz ◽  
Avi Kornblit ◽  
Daniel Lopez ◽  
Haim Grebel
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Vapor Deposition ◽  
Low Temperatures ◽  
Chemical Vapor ◽  
Single Wall Carbon Nanotube ◽  
Single Wall Carbon ◽  
Multi Wall Carbon Nanotube

AbstractIntra-connects (bridges spanning across in plane electrodes), which were made of carbon nanotube (CNT), were fabricated by CO Plasma Enhanced Chemical Vapor Deposition (PECVD), ethanol CVD and pyrolitic CO CVD. CO PECVD has been used with CO/H2 mixture at relatively low temperatures. Its yield was relatively low though and the quality of CNT intra-connect was not to par. Ethanol CVD resulted in many more multi-wall carbon nanotube (MWCNT) than single-wall carbon nanotube (SWCNT) intra-connects. CO CVD was the most effective and simplest way to grow CNT interconnects among the three methods, yielding well-aligned and straight SWCNT bridges.

Synthesis of Carbon Nanotubes from Silicalite-1-Coated Substrates

2012 ◽  
Vol 512-515 ◽  
pp. 275-279
Author(s):  
Wei Zhao ◽  
Ashish Pokhrel ◽  
Hyun Sung Kim ◽  
Hyung Tae Kim ◽  
Ik Jin Kim
Keyword(s):  
Carbon Nanotubes ◽  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Iron Oxide ◽  
Vapor Deposition ◽  
Rf Sputtering ◽  
Chemical Vapor ◽  
Confined Spaces ◽  
Synthesis Of Carbon Nanotubes ◽  
Si Wafer

Assembled monolayer of silicalite-1 (AMS) microcrystals on Si wafer for carbon nanotube (CNT) growth has been prepared by the rubbing method. Iron oxide (α-Fe2O3, hematite) catalyst films were deposited onto silicate-1 monolayers from a Fe2O3 target by radio frequency (rf)-sputtering. This approach has the potential for producing well-aligned CNTs with controlled diameter from predesigned silicalite-1 templates by catalytic chemical vapor deposition (CCVD). Silicalite-1 monolayer oriented with faces parallel to Si wafer showed only the planes in the forms {0 k 0} lines at (020), (040), (060), (080) and (0100) by XRD. The formation and growth of CNTs by CCVD were achieved on the pores of silicate-1 crystals whereby the pores can be defined as confined spaces (channels, 5.60 Å) in nanometer dimensions acting as a template for a fine dispersion of well-defined Fe2O3 (10-15 nm) particles.

A Comprehensive Multiphysics, Multiscale Study of Reactor Chamber and Substrate Orientation Effects on Carbon Nanotube Synthesis During Chemical Vapor Deposition Process

2008 ◽  
Author(s):  
Mahmoud Reza Hosseini ◽  
Nader Jalili ◽  
David A. Bruce
Keyword(s):  
Chemical Vapor Deposition ◽  
Carbon Nanotube ◽  
Temperature Profile ◽  
Gas Phase ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Physical Property ◽  
Fabrication Process ◽  
Multiphase Model ◽  
Gas Phase Reactions

A comprehensive multiphysics, multiphase model of carbon nanotube (CNT) fabrication process by chemical vapor deposition (CVD) is utilized to study the effects of several physical phenomena inside the quartz tube. The investigations include fluid flow properties, temperature profile and heat transfer as well as diffusion and concentration of carbon species along the substrate. These properties are examined in a great detail for a horizontally placed substrate. For each physical property, the effects of substrate dislocation as well as the angle between substrate and reactor chamber longitudinal axis are investigated. It is shown that the temperature in the gas phase reactions region is significantly lower compared to the temperature profile around the substrate. Based on the obtained results, two new CVD system designs are proposed to enhance the temperature in the reactor chamber section where gas phase reactions take place. Moreover, it is shown that substrate dislocation and angle change result in physical property change such as species concentration on upper and lower substrate surfaces. This study is also applicable to other CVD-based fabrication process such as deposition of any layer, since the methodology of the fabrication process remains the same.

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