Absolute radical density measurements in a CH4H2 d.c. discharge

Menningen, K. L.; Childs, M. A.; Toyoda, Hirotaka; Ueda, Y.; Anderson, L. W.; Lawler, J. E.

doi:10.1016/0925-9635(94)90196-1

Cited by 12 publications

(7 citation statements)

References 26 publications

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“…The CH 3 radical has been thought to be one of the important species for diamond growth. The CH 3 radical has been detected by appearance mass spectroscopy [20], absorption spectroscopy in the UV [21] and IR [22] ranges and multiphoton ionization by a laser [23]. In this work, the CH 3 radical density is measured by using IRLAS to appreciate the contribution of the radical to the diamond growth and the effect of pulse modulation on the radical density.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of diamond films at low temperature by pulse-modulated magneto-active microwave plasma CVD

Hatta

Suzuki

Kadota

et al. 1996

Plasma Sources Sci. Technol.

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A magneto-active microwave plasma chemical vapour deposition technique was developed by pulse modulation of the discharge to reduce the time-averaged microwave power for diamond film synthesis at low temperature. Due to a threshold power being required to start growth, the practical growth rate obtained by using the pulse-modulated plasma became three times larger than that obtained by using a continuous plasma of time-averaged power near the threshold. The methyl (CH 3 ) radical density was measured in continuous or pulse-modulated plasma by infrared laser absorption spectroscopy and compared to the growth rate. The time-averaged CH 3 radical density was also enhanced by pulse modulation; it was up to 1.3 times larger than that in the continuous plasma. Though the correlation between CH 3 density and diamond growth rate was not clear, the number of carbon atoms supplied as CH 3 radicals was larger than the actual growth rate by almost two orders of magnitude.

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Section: Introductionmentioning

confidence: 99%

Fabrication of diamond films at low temperature by pulse-modulated magneto-active microwave plasma CVD

Hatta

Suzuki

Kadota

et al. 1996

Plasma Sources Sci. Technol.

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“…Also, given the large spatial extension of light sources used in BBAS, the spatial resolution perpendicular to the optical path is often limited to several millimeters. This technique has been widely used in hydrocarbon [31,32], fluorocarbon [29,33], and chlorine based [30,34] process plasmas.…”

Section: Broad-band Absorptionmentioning

confidence: 99%

“…This « ringdown time » τ is monitored while the laser wavelength is tuned across absorption features of the sample. Considering the reflection coefficient R of the mirrors (1 -R < 10 -4 for good ones) and the absorption coefficient of the sample, α, the decay rate of the trapped photons is: (31) where c is the speed of light, l is the length of the absorbing sample and L the cavity length. 1/τ 0 is the decay time when the laser wavelength is set outside of absorption features.…”

Section: (2) Cavity Ringdown Spectroscopy (Crds)mentioning

confidence: 99%

6. Molecular Spectroscopy Techniques Applied for Processing Plasma Diagnostics

Sadeghi

2004

J. Plasma Fusion Res.

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Optical diagnostics are between the most commonly used tools for the characterization of plasmas and for the better understanding of physical and chemical processes controlling their time and space dependencies. In this review paper the most popular spectroscopy techniques are described and examples of their applications to plasmas are indicated. An special emphasis is given to power saturation phenomena, encountered in laser based diagnostics. Numerical applications show that with commonly available lasers a great care must be taken to avoid saturation and to be really non-intrusive, as expected for a diagnostic tool.

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“…The spectroscopy system used in our work has been described in detail elsewhere [1,3,8,9]. Figure 3 is a schematic diagram of our white-light absorption spectroscopy system.…”

Section: The Experimental Apparatus and Proceduresmentioning

confidence: 99%

“…The work presented here is the first measurement of gas phase radical concentrations by the use of high-sensitivity white-light absorption spectroscopy in a microwave plasma-assisted CVD (MPACVD) diamond growth system. This highsensitivity optical absorption spectroscopy technique has been applied previously both to hot-filament CVD [1][2][3][4][5][6] and to hollow-cathode DC discharge CVD [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

High-sensitivity absorption spectroscopy on a microwave plasma-assisted chemical vapour deposition diamond growth facility

Erickson

Jameson

Watts-Cain

et al. 1996

Plasma Sources Sci. Technol.

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High-sensitivity absorption spectroscopy using a multi-element detector was performed on a microwave plasma-assisted chemical vapour deposition (MPACVD) diamond growth facility. The absolute methyl radical column density and the line-of-sight average of the gas temperature were measured as functions of position in the discharge with input methane concentration 0-1%. The average absolute methyl radical density [CH 3 ] was nearly independent of position in the discharge and varied in the range (1-6)×10 13 cm −3 as the input CH 4 mole fraction varied in the range 0-1%. The gas temperature was measured using H 2 emission spectroscopy and was found to be 1200 ± 100 K independent of position throughout the discharge. An upper bound of 10 10 cm −3 was placed on the CH density, which gives an upper bound of 0.008 on the hydrogen dissociation ratio [H]/[H 2 ].

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Absolute radical density measurements in a CH4H2 d.c. discharge

Cited by 12 publications

References 26 publications

Fabrication of diamond films at low temperature by pulse-modulated magneto-active microwave plasma CVD

Fabrication of diamond films at low temperature by pulse-modulated magneto-active microwave plasma CVD

6. Molecular Spectroscopy Techniques Applied for Processing Plasma Diagnostics

High-sensitivity absorption spectroscopy on a microwave plasma-assisted chemical vapour deposition diamond growth facility

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