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Mechanism And Characterization Studies on Boron Carbides Deposited by Chemical Vapor Deposition Technique

Published online by Cambridge University Press:  01 February 2011

Mustafa Karaman
Affiliation:
[email protected], Middle East Technical University, Chemical Engineering, ODTU Kimya Muhendisligi Blm., Ankara, Ankara, 06531, Turkey, 05334377828, 03122101264
Hilmi Önder Özbelge
Affiliation:
[email protected], Middle East Technical University, Chemical Engineering, Turkey
Naime Asli Sezgi
Affiliation:
[email protected], Middle East Technical University, Chemical Engineering, Turkey
Timur Doğu
Affiliation:
[email protected], Middle East Technical University, Chemical Engineering, Turkey
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Abstract

Boron carbide was produced in an impinging jet CVD reactor from a gas mixture of BCl3, CH4 and H2. The mass transfer limitations on the reaction kinetics were minimised by the jet impingement on the substrate surface. XPS characterization of the produced deposits revealed a nearly pure boron carbide phase containing small amounts of oxy-boron and oxy-carbon species. After a detailed kinetic study, a reaction model was proposed to predict the rates of boron carbide and dichloroborane formation reactions. In this model, boron trichloride is adsorbed on the surface non-dissociatively, whereas hydrogen and methane are adsorbed dissociatively. BC is formed on the solid surface through the reaction of adsorbed boron trichloride with adsorbed methane in the form of CH3(s) (adsorbed CH3 on the surface). Produced BC is reacted in successive series reactions including adsorbed boron trichloride and adsorbed hydrogen. In the proposed mechanism, dichloroborane is produced only through the gas phase reaction between boron trichloride and hydrogen. The simultaneous fit of the experimental data to the model expression gave good fits for the boron carbide and dichloroborane formation reactions with the high correlation coefficient values.

Type
Research Article
Copyright
Copyright © Materials Research Society 2006

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References

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