Diagnostics of boundary layer chemistry in thermal plasma CVD

Conference · Sat Jul 01 04:00:00 EDT 1995

OSTI ID:223669

Owano, T G; Wahl, E H; Kruger, C H ^[1]

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1. Stanford Univ., CA (United States)

Chemical Vapor Deposition (CVD) using thermal plasmas is attractive for diamond synthesis applications due to the inherently high reactant densities and throughput, but the associated high gas-phase collision rates in the boundary layer above the substrate produce steep thermal and species gradients which can drive the complex plasma chemistry away from optimal conditions. To understand and control these environments, accurate measurements of temperature and species concentrations within the reacting boundary layer are needed. This is challenging in atmospheric pressure reactors due to the highly luminous environment, steep thermal and species gradients, and small spatial scales. The applicability of degenerate four-wave mixing (DFWM) as a spectroscopic probe of atmospheric pressure reacting plasmas has been investigated. This powerful, nonlinear technique has been applied to the measurement of temperature and radical species concentrations in the boundary layer of a diamond growth substrate immersed in a flowing atmospheric pressure plasma. In-situ measurements of CH and C{sub 2} radicals have been performed to determine spatially resolved profiles of vibrational temperature, rotational temperature, and species concentration. Results of these measurements are compared with the predictions of a detailed numerical simulation.

• Research Organization: International Union of Pure and Applied Chemistry; American Physical Society, New York, NY (United States)
• OSTI ID: 223669
• Report Number(s): CONF-950875--Vol.4
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ABSORPTION SPECTROSCOPY
CHEMICAL VAPOR DEPOSITION
DIAMONDS
PLASMA
PLASMA HEATING
RADICALS
TEMPERATURE MEASUREMENT