Numerical Simulation of Gas Phase Growth Environment of Carbon Nanotube Synthesis by Plasma-Enhanced Chemical Vapor Deposition

2005 ◽  
Author(s):  
R. K. Garg ◽  
J. P. Gore ◽  
T. S. Fisher
Keyword(s):  
Gas Phase ◽  
Reaction Mechanisms ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Phase Reaction ◽  
Phase Growth ◽  
Growth Environment ◽  
Hydrogen Mixture

The gas-phase growth environment of carbon nanotubes has been simulated using different published chemical reaction mechanisms for a gas mixture of methane and hydrogen. Detailed chemical analysis of the growth environment is important in identifying precursor species responsible for CNT formation and is useful in understanding fundamental mechanisms that ultimately could allow control of the CNT synthesis process. The present simulations seek to compare the roles of different gas phase reaction mechanisms and to identify precursors for CNT formation. The results show that inlet methane-hydrogen mixture converts primarily to a acetylene-hydrogen mixture, and C2H2, CH3, H2, and H are the main precursors formed in the plasma under experimentally verified CNT growth conditions in a microwave plasma reactor.

Nanoparticles generated by combining hot wall and microwave plasma chemical vapor synthesis

MRS Advances ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 213-218
Author(s):  
Alexander Levish ◽  
Markus Winterer
Keyword(s):  
Iron Oxide ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Process Window ◽  
Chemical Vapor Synthesis ◽  
Second Stage ◽  
Structure Surface ◽  
Oxide Phases ◽  
Precursor Decomposition

ABSTRACTControlling the oxidation state of iron and the crystal structure of iron containing compounds is the key to improved materials such as iron oxide nanoparticles for cancer treatment or heterogeneous catalysis. Iron oxides contain iron in different oxidation states and form different phases for one valence state (α-Fe3+2O2-3, β- Fe3+2O-32, etc.). Chemical vapor synthesis (CVS) allows the reproducible production of pure nanocrystals with narrow size distribution where particle formation and growth take place in the gas phase. Through the controlled variation of synthesis parameters CVS enables the synthesis of diverse iron oxide phases. In this study the energy for the CVS process is supplied by a hot wall furnace and a microwave plasma. The advantage of an plasma reactor as the first CVS stage is the fast and complete precursor decomposition at low temperatures. This results in a larger process window for the hot wall reactor in the second stage. The nanoparticles are examined regarding their structure, surface and valence by XRD and TEM.

scholarly journals Catalyst-Less and Transfer-Less Synthesis of Graphene on Si(100) Using Direct Microwave Plasma Enhanced Chemical Vapor Deposition and Protective Enclosures

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5630
Author(s):  
Rimantas Gudaitis ◽  
Algirdas Lazauskas ◽  
Šarūnas Jankauskas ◽  
Šarūnas Meškinis
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Gas Flow ◽  
Microwave Plasma ◽  
Lattice Mismatch ◽  
Chemical Vapor ◽  
Hydrogen Gas ◽  
Synthesis Process ◽  
Synthesis Time ◽  
Graphene Layers

In this study, graphene was synthesized on the Si(100) substrates via the use of direct microwave plasma-enhanced chemical vapor deposition (PECVD). Protective enclosures were applied to prevent excessive plasma etching of the growing graphene. The properties of synthesized graphene were investigated using Raman scattering spectroscopy and atomic force microscopy. Synthesis time, methane and hydrogen gas flow ratio, temperature, and plasma power effects were considered. The synthesized graphene exhibited n-type self-doping due to the charge transfer from Si(100). The presence of compressive stress was revealed in the synthesized graphene. It was presumed that induction of thermal stress took place during the synthesis process due to the large lattice mismatch between the growing graphene and the substrate. Importantly, it was demonstrated that continuous horizontal graphene layers can be directly grown on the Si(100) substrates if appropriate configuration of the protective enclosure is used in the microwave PECVD process.

Characterization and Tribological Properties of Nanostructured Copper/Carbon Composite Films Prepared by Microwave Plasma-Assisted Dual Deposition Processes

2002 ◽  
Vol 750 ◽  
Author(s):  
François Thiery ◽  
Yves Pauleau ◽  
Jacques Pelletier
Keyword(s):  
Amorphous Carbon ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Composite Films ◽  
Chemical Vapor ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Carbon Films ◽  
Radius Of Curvature

ABSTRACTNanocrystalline copper/hydrogenated amorphous carbon films have been deposited on Si substrates at the floating potential using a distributed electron cyclotron resonance microwave plasma reactor. In this deposition technique, the microwave plasma-enhanced chemical vapor deposition process of carbon from argon-methane or argon-acetylene mixtures of various compositions was associated with the sputter deposition of copper from a copper target. The total pressure was fixed at 0.13 Pa. For deposition, the substrates mounted on a water-cooled substrate holder were maintained at ambient temperature. The composition of films determined by Rutherford backscattering spectroscopy, energy recoil detection analyses and nuclear reaction analyses was investigated as a function of the gas phase composition. The structure of films was identified by X-ray diffraction (XRD) techniques and the size of copper crystallites incorporated in the amorphous carbon matrix was deduced from XRD data. The magnitude of residual stresses developed in these films was calculated from the radius of curvature of film/substrate samples determined by profilometry. The residual stress values were found to be nearly independent on the composition of films and deposition parameters.

Effect of Two-Step Deposition Process on Morphology and Optical Properties of Nanostructured Diamond Films

2013 ◽  
Vol 651 ◽  
pp. 148-153 ◽  
Author(s):  
S. Tipawan Khlayboonme ◽  
Wicharn Techitdheera ◽  
Warawoot Thowladda
Keyword(s):  
Optical Properties ◽  
Carbon Content ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Single Step ◽  
Second Step ◽  
Step Process

The morphology and optical properties of nanostructured diamond films affected by the two-step deposition process with changing CH4 concentration were investigated. The CH4 concentration was 1% for the first step and 2% for the second step. The films were prepared by chemical vapor deposition in a microwave plasma reactor with a CH4/H2 gas mixture. Nanocrystalline columnar-structured diamond film with lowering of sp2-bonded carbon content was achieved by the two-step deposition process. Unlike that of the single-step process with 1%CH4, the two-step process promoted the morphology to more uniform and smoother film. The two-step process increased the higher grain boundary as well as decreased the sp2-bonded carbon content in the film, as compared with the single-step process with 2%CH4Subscript text.

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