Analysis of diamond growth in subatmospheric dc plasma-gun reactors

The growth of diamond in a subatmospheric dc-arc plasma-jet reactor has been studied theoretically. Full transport equations for this geometry, including gas-phase and surface chemistry, have been solved numerically. The surface-reaction mechanism includes pathways for the incorporation of CH3, C2H2...

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Bibliographic Details
Published in:Journal of applied physics 1993-11, Vol.74 (9), p.5803-5820
Main Authors: COLTRIN, M. E, DANDY, D. S
Format: Article
Language:English
Subjects:
400201 > Chemical & Physicochemical Properties
ALKANES
CARBON
CHEMICAL COATING
CHEMICAL REACTIONS
CHEMICAL VAPOR DEPOSITION
Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.)
Cross-disciplinary physics: materials science
rheology
DEPOSITION
DIAMONDS
DISSOCIATION
ELEMENTAL MINERALS
ELEMENTS
Exact sciences and technology
GROWTH
HYDROCARBONS
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
MATERIALS SCIENCE
METHANE
Methods of crystal growth
physics of crystal growth
Methods of deposition of films and coatings
film growth and epitaxy
MINERALS
NONMETALS
ORGANIC COMPOUNDS
Physics
PLASMA GUNS
SURFACE COATING 360601 > Other Materials-- Preparation & Manufacture
SURFACES
Theory and models of crystal growth
physics of crystal growth, crystal morphology and orientation
Theory and models of film growth
THIN FILMS
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Summary:The growth of diamond in a subatmospheric dc-arc plasma-jet reactor has been studied theoretically. Full transport equations for this geometry, including gas-phase and surface chemistry, have been solved numerically. The surface-reaction mechanism includes pathways for the incorporation of CH3, C2H2, and C from the gas phase, as well as growth of graphite. The surface mechanism includes full reversibility for all reactions, based on estimates of the thermochemistry. Results are presented for degrees of dissociation of H2 in the plasma gun ranging from 2.6% to 90%, and inlet levels of CH4 spanning 0.1–5.0 mol %. It is seen that CH3 is the predominant growth species when there is little H2 dissociation within the plasma gun, but C becomes the dominant species at higher dissociation levels. The third growth species, C2H2, does not play a role in diamond growth under these conditions when there is less than 1% CH4 in the feed; but, at higher CH4 levels both C and CH3 addition rates drop to 50 times greater than C2H2.
ISSN:0021-8979
1089-7550
DOI:10.1063/1.354201