Atomic hydrogen concentration in a diamond depositing dc arcjet determined by calorimetry

Journal Article · Sun Jun 01 04:00:00 EDT 1997 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.365411· OSTI ID:530025

Juchmann, W; Luque, J; Jeffries, J B ^[1]

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1. Molecular Physics Laboratory, SRI International, 333 Ravenswood Avenue, Menlo Park, California 94025 (United States)

The fraction of hydrogen dissociated in the plume of a dc arcjet used for diamond deposition is determined by calorimetry to be 0.33{plus_minus}0.12. A dc arc is struck in a mixture of argon and hydrogen at 90 psi and the effluent is expanded through a converging/diverging nozzle into a reactor maintained at 25 Torr. Methane ({lt}1{percent}) is added to the luminous gas plume in the diverging nozzle. This supersonic jet impinges on a water cooled molybdenum substrate, and diamond thin film grows from the reactive mixture. The electrical power input of the arcjet (1.6 kW) is balanced by the power losses due to cooling of the nozzle, enthalpy change in the gas, ionization of the gas, dissociation of H{sub 2}, and the directed velocity of the gas phase. The gas temperature is determined by linear laser-induced fluorescence (LIF) measurements of several rotational lines of NO seeded to the gas plume. The velocity of the gas plume is obtained via the Doppler shift between LIF signals measured simultaneously in a stationary reference cell and in the arcjet. The atomic hydrogen fraction increases as a function of the feedstock H{sub 2}/Ar ratio and with increasing input power to the arcjet. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 530025
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 81; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CALORIMETRY
CHEMICAL COMPOSITION
CHEMICAL VAPOR DEPOSITION
DIAMONDS
DISSOCIATION
HYDROGEN ADDITIONS
SUPERSONIC FLOW
THIN FILMS