Hydrogen assisted heat transfer during diamond growth using carbon and tantalum filaments

Yarbrough, Walter A.; Tankala, K.; Mecray, M.; DebRoy, T.

doi:10.1063/1.107091

Cited by 37 publications

(5 citation statements)

References 15 publications

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“…Moreover, its exothermic recombination (À104 kcal/mole) at the surface led to the temperature rising. 33 For increasing microwave power/pressure conditions, more and more atomic hydrogen is interacting with the ND surface leading to an efficient oxygen removal for T > 700 1C. During the CVD exposure, chemical interactions with reactive atomic hydrogen (etching, carbon redeposition, surface passivation) and thermal activated mechanisms (desorption) are taking place simultaneously at the ND surface.…”

Section: Surface Modifications Induced By Different Hydrogen Mpcvd Pl...mentioning

confidence: 99%

Surface chemical modifications and surface reactivity of nanodiamonds hydrogenated by CVD plasma

Arnault

Petit

Girard

et al. 2011

Phys. Chem. Chem. Phys.

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The present study focuses on the interaction of hydrogen microwave CVD plasma with nanodiamonds (NDs). Hydrogen treated NDs (H-NDs) were characterized using electron spectroscopies (XPS, AES) without air exposure. A surface temperature higher than 700 °C is needed to remove the oxygen present on raw NDs. The kinetics of oxygen removal were investigated. Moreover, UHV annealings of H-NDs after ageing in ambient air clearly underline that 75% of the oxygen is related to physisorbed species. Finally, H-NDs were efficiently grafted using photochemical reaction with alkenes and a spontaneous coupling of aryldiazonium salts. These results confirm similar electronic surface properties between bulk and nano diamond materials.

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Section: Surface Modifications Induced By Different Hydrogen Mpcvd Pl...mentioning

confidence: 99%

Surface chemical modifications and surface reactivity of nanodiamonds hydrogenated by CVD plasma

Arnault

Petit

Girard

et al. 2011

Phys. Chem. Chem. Phys.

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“…The main power dissipation pathways revealed by the 2D modeling are (i) thermal conduction fluxes, from the hot plasma to the reactor walls, baseplate and top plate (window), (ii) radiation losses and (iii) substrate heating -both from the thermal conduction flux and from the incident flux of atomic H. Notwithstanding the very high [H]/[H 2 ] ratio ($2.5) in the core of the hot UNCD plasma [X 0 (H 2 ) ¼ 1%], the actual H atom concentration in these plasmas is $3.7 Â lower than that in the core of the base plasma [X 0 (H 2 ) ¼ 14.7%, P ¼ 1 kW]. The lower [H] must result in reduced substrate heating 46 from H atom adsorption at the C* surface radical sites. 47 Another, more important, reason for the observed drop in T sub when operating with UNCD plasma conditions [T sub $785 K, cf.…”

Section: Variations In Reactor Parameters: 2d Model Versus Experimmentioning

confidence: 99%

Combined experimental and modeling studies of microwave activated CH4/H2/Ar plasmas for microcrystalline, nanocrystalline, and ultrananocrystalline diamond deposition

Richley

Fox

Ashfold

et al. 2011

Journal of Applied Physics

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A comprehensive study of microwave (MW) activated CH 4 /H 2 /Ar plasmas used for diamond chemical vapor deposition is reported, focusing particularly on the effects of gross variations in the H 2 /Ar ratio in the input gas mixture (from H 2 /Ar mole fraction ratios of > 10:1, through to $1:99). Absolute column densities of C 2 (a) and CH(X) radicals and of H(n ¼ 2) atoms have been determined by cavity ringdown spectroscopy, as functions of height (z) above a substrate and of process conditions (CH 4 , H 2 , and Ar input mole fractions, total pressure, p, and input microwave power, P). Optical emission spectroscopy has also been used to explore the relative densities of electronically excited H atoms, and CH, C 2 , and C 3 radicals, as functions of these same process conditions. These experimental data are complemented by extensive 2D (r, z) modeling of the plasma chemistry, which provides a quantitative rationale for all of the experimental observations. Progressive replacement of H 2 by Ar (at constant p and P) leads to an expanded plasma volume. Under H 2-rich conditions, > 90% of the input MW power is absorbed through rovibrational excitation of H 2. Reducing the H 2 content (as in an Ar-rich plasma) leads to a reduction in the absorbed power density; the plasma necessarily expands in order to accommodate a given input power. The average power density in an Ar-rich plasma is much lower than that in an H 2-rich plasma operating at the same p and P. Progressive replacement of H 2 by Ar is shown also to result in an increased electron temperature, an increased [H]/[H 2 ] number density ratio, but little change in the maximum gas temperature in the plasma core (which is consistently $3000 K). Given the increased [H]/[H 2 ] ratio, the fast H-shifting (C y H x þ H $ C y H xÀ1 þ H 2 ; y ¼ 1À3) reactions ensure that the core of Ar-rich plasma contains much higher relative abundances of "product" species like C atoms, and C 2, and C 3 radicals. The effects of Ar dilution on the absorbed power dissipation pathways and the various species concentrations just above the growing diamond film are also investigated and discussed. V

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“…So only electron bombardment effects have been considered here. Yarbrough et al 10 observed that recombination reactions of atomic hydrogen, which is highly exothermic and the energy released heats the substrate, at the diamond growing surface have produced a pronounced increase of the substrate temperature. First, a possible reason is due to the increase of substrate temperature.…”

Section: Resultsmentioning

confidence: 99%

Effects of substrate bias on the structural and field emission properties of diamond films

Shim

Joon

Baik

et al. 2000

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Defect structure and electron field-emission properties of boron-doped diamond filmsThe effect of electron bombardment on modification of the structural property and the surface morphology of diamond films, and consequently the field emission properties have been investigated by introducing positive substrate bias. When increasing the bias voltage, the structural properties of diamond films are significantly deteriorated together with the increase of nondiamond carbon component and the surface morphologies of the films lost their unique facet shape. The reason for the increase of nondiamond carbon content is described in terms of both the increase of substrate temperature and the excessive generation of CH n radicals. The field emission properties of diamond films were substantially improved with increasing bias voltage. Enhancement of field emission property for the films prepared by increasing bias voltage and/or methane concentration has been discussed by correlating between the substrate-diamond interface property and the slope of the Fowler-Nordheim plot.

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Hydrogen assisted heat transfer during diamond growth using carbon and tantalum filaments

Cited by 37 publications

References 15 publications

Surface chemical modifications and surface reactivity of nanodiamonds hydrogenated by CVD plasma

Surface chemical modifications and surface reactivity of nanodiamonds hydrogenated by CVD plasma

Combined experimental and modeling studies of microwave activated CH4/H2/Ar plasmas for microcrystalline, nanocrystalline, and ultrananocrystalline diamond deposition

Effects of substrate bias on the structural and field emission properties of diamond films

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