Methyl halides as carbon sources in a hot-filament diamond CVD reactor: A new gas phase growth species

Bai, Benjamin J.; Chu, Judith; Patterson, Donald E.; Hauge, Robert H.; Margrave, John L.

doi:10.1557/jmr.1993.0233

Cited by 39 publications

(12 citation statements)

References 2 publications

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“…Finally, the observation that the film growth rate is independent of the carbon inlet identity is consistent with Bai who found no preference for fluorine-based diamond growth using isotopic labeling. 35 The lack of atomic fluorine incorporation into the film during deposition provides further support for the hypothesis that diamond growth proceeds via the same radicals for the halocarbon and hydrocarbon mixtures. Figure 17 following a two hour deposition using 0.6% CH,F/H, at 660°C.…”

Section: Gas Injecti Portsmentioning

confidence: 84%

The chemistry of halogens on diamond: effects on growth and electron emission

Hsu¹,

Pan²,

Brown³

1997

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Portions of this ABSTRACTThe feasibility of diamond growth using halogenated precursors was studied in several diamond growth reactors. In a conventional microwave plasma reactor, diamond growth using the following gas mixtures was studied: CF4/H,, CH4/H,, CH,F/H,, and CH,Cl/H,. Both' the diamond growth measurements (film growth rate, film quality, etc.) and in-situ near-surface gas composition measurements demonstrated ineffective transport of halogen radicals to the diamond surface during the growth process. In order to transport radical halogen species to the diamond surface during growth, a flow-tube reactor was constructed which minimized gas phase reactions. In addition, the flow-tube reactor enabled pulsed gas transport to the diamond surface by fast-acting valves. Molecular beam mass spectroscopy was used to find conditions which resulted in atomic hydrogen and/or atomic fluorine transport to the growing diamond surface. Although such conditions were found, they required very low pressures (.5 Torr and below); these low pressures produce radical fluxes which are too low to sustain a reasonable diamond growth rate. Due to the limitations of both the conventional plasma reactor and the flow-tube reactor, the sequential reactor at Stanford University was modified to add a halogen-growth step to the conventional atomic hydrogerdatomic carbon diamond growth cycle. Since the atomic fluorine, atomic hydrogen, and atomic carbon environments are independent in the sequential reactor, the effect of fluorine on diamond growth could be studied independently of gas phase reactions. Although the diamond growth rate was increased by the use of fluorine (compared to growth without fluorine under similar conditions), the film quality was seen to deteriorate as well as the substrate surface. Moreover, materials incompatibilities with fluorine significantly limited the use of fluorine in this reactor.A diamond growth model incorporating both gas phase and surface reactions was developed for the halocarbon system concurrent with the film growth efforts. In this experiments done to understand fluorine interaction with diamond surfaces. In addition, fluorine modification of diamond surfaces after growth is used to prepare cesiated-diamond cathodes which have field emission characteristics that are both air stable and thermally stable (200°C).

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Section: Gas Injecti Portsmentioning

confidence: 84%

The chemistry of halogens on diamond: effects on growth and electron emission

Hsu¹,

Pan²,

Brown³

1997

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“…Similarly, as C 2 H 2 being the input carbon source, C 2 H 2 is the dominant carbon species. Also, only 5% of C 2 H 2 is con- verted into CH 4 . Thus, the carbon species near the substrate surface is determined by the identity of the input carbon source.…”

Section: Resultsmentioning

confidence: 99%

“…1 Halogen atoms, due to their bonding characteristics similar to those of H atoms, have been studied by many groups to characterize their effects on diamond growth. [2][3][4][5][6][7][8][9][10][11] Cl atom is a potential candidate to partially replace H atom with the advantage of being more active toward hydrogen abstraction 2,3,5 from C-H and less harmful to diamond nuclei. 3,9 Besides, Cl 2 can be dissociated more readily than H 2 to generate a high concentration of radicals.…”

Section: Introductionmentioning

confidence: 99%

Diamond growth by injecting thermally decomposed chlorine atoms into methane/hydrogen mixture

Hong

1997

Journal of Applied Physics

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Crystalline diamond has been successfully deposited by injecting thermally decomposed Cl atoms into CH4/H2 in a hot-tube system at an extremely high flow velocity (in the convection-dominant mass transport region). Diamond growth rate increased with increasing the total flow rate, suggesting the increase of [Cl]/[H] ratio near the growth surface. Film quality also improved with increasing the total flow rate as well as reducing the reactor pressure. Both the quality and film growth rate were enhanced as the inlet [Cl2] increased, due to the increase of total radical concentration. Two distinct growth activation energies were measured ranging from 3.6 kcal/mol in the substrate temperature range of 600–750 °C to 7.9 kcal/mol in the temperature range of 400–600 °C. Owing to the extremely short residence time and low gas temperature, carbon species near the growth surface remained almost the same as the input carbon source. By employing almost pure CH4 or C2H2 near the substrate surface, the CH3 radical was shown to be a more efficient diamond growth precursor than C2H2. With almost pure C2H2 near the surface, diamond deposition was negligible in a wide range of conditions on either silicon or diamond surfaces.

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“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Cl-related chemistry is of particular interest to several groups. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Cl-related chemistry is of particular interest to several groups.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Cl-related chemistry is of particular interest to several groups. Bai et al 6 also showed that the chlorocarbon radical was a more effective growth species than the methyl radical. Bai et al 6 also showed that the chlorocarbon radical was a more effective growth species than the methyl radical.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Chloromethane on Diamond Nucleation and Growth in a Hot-filament Chemical Vapor Deposition Reactor

Wu¹,

Hong²

1998

J. Mater. Res.

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The effects of chloromethane on diamond nucleation and growth were studied by employing laser reflective interferometry. Chloromethane enhances the film-growth rate only slightly compared to methane. However, chloromethane greatly enhances the nucleation density and shortens the film-forming stage, more significantly at a lower temperature. Thus, chloromethane facilitates the low temperature growth mainly through the enhancement of nucleation. Nucleation density is strongly dependent on the compositions of H atoms and carbon species prior to diamond growth. The residual diamond seeds by diamond-grit scratching are suggested to be the major nucleation sites. Chloromethane can enhance diamond nucleation by protecting the residual seeds from being etched by H atoms.

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Methyl halides as carbon sources in a hot-filament diamond CVD reactor: A new gas phase growth species

Cited by 39 publications

References 2 publications

The chemistry of halogens on diamond: effects on growth and electron emission

The chemistry of halogens on diamond: effects on growth and electron emission

Diamond growth by injecting thermally decomposed chlorine atoms into methane/hydrogen mixture

The Effects of Chloromethane on Diamond Nucleation and Growth in a Hot-filament Chemical Vapor Deposition Reactor

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