Chemistry and kinetics of chemical vapor deposition of pyrocarbon — V influence of reactor volume/deposition surface area ratio

Becker, A.; Hüttinger, Klaus J.

doi:10.1016/s0008-6223(97)00178-4

Cited by 50 publications

(40 citation statements)

References 6 publications

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“…The results were obtained with a deposition tube, 22 mm in diameter and 20 mm in height; the tube was made of a high-density alumina ceramic containing 99.7 % alumina. To avoid decomposition of methane before entering into the deposition tube and to generate a plug flow, a conical inlet nozzle with a cone angle of 60°w as used; [9] a scheme of the reactor is shown in the Experimental section.…”

Section: Resultsmentioning

confidence: 99%

“…Assuming equivalent possibilities of chemisorption and gas-phase reactions a fraction of C 2 -species may finally form C 6 -species, i.e., benzene, phenyl radical, or similar sixmembered ring species including methyl substituted species. C 4 -species such as C 4 H 4 , C 4 H 5 , and possibly C 4 H 6 are intermediates in the formation of C 6 -species, [8][9][10] at the temperatures considered C 4 H 3 should not be formed at all or only to a negligible extent. [11] The reaction sequence in the gas phase has been terminated with C 6 -species.…”

Section: Model Considerationsmentioning

confidence: 97%

“…Thus, synthesis reactions with CH 3 have to be considered. Possible reaction products are C 2 H 6 , C 2 H 5 , C 2 H 4 , C 2 H 3 , and C 2 H 2 , [8] summarized as "C 2 " in Figure 1. With the exception of ethane, these species have the same reaction possibilities as discussed in the case of the methyl radical.…”

Section: Model Considerationsmentioning

confidence: 99%

“…In particular, acetylene should be able to chemisorb even at blocked carbon edge atoms forming a carbon/hydrogen (C(H))-surface complex. [9] On the other hand, such species are also highly reactive in homogeneous gas-phase reactions. Consequently, the competition between chemisorption and homogeneous gas-phase reactions of C 2 -species has to be considered as in the case of the methyl radical.…”

Section: Model Considerationsmentioning

confidence: 99%

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CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

Hüttinger¹

1998

Chem. Vap. Deposition

129

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The paper is concerned with chemical vapor deposition in hot wall reactors and in particular with the interaction of homogeneous gas-phase and heterogeneous surface reactions. Based on model considerations it is shown that this interaction has a tremendous influence on the deposition chemistry and kinetics in all cases in which the precursor gas undergoes complex gasphase reactions. The decisive parameter determining the interaction is given by the ratio of free volume of the deposition space and size of the surface area of the substrate; it is termed the "third parameter" of chemical vapor deposition. Predictions from the model are experimentally confirmed using results on chemical vapor deposition of pyrolytic carbon from methane. The importance of this "third parameter" of chemical vapor deposition in investigations of kinetics and for technical processes of chemical vapor deposition and infiltration is discussed in the conclusion.

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Section: Resultsmentioning

confidence: 99%

Section: Model Considerationsmentioning

confidence: 97%

Section: Model Considerationsmentioning

confidence: 99%

Section: Model Considerationsmentioning

confidence: 99%

See 2 more Smart Citations

CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

Hüttinger¹

1998

Chem. Vap. Deposition

129

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“…The PyCs with a variety of morphology, texture and structure have been obtained, depending on the deposition parameters including deposition temperature, carbon source, types of substrate and even the geometry of reaction chamber. The deposition kinetics and mechanism of pyrolytic carbon have been studied quite extensively by many researchers [14][15][16][17][18][19][20][21][22]. One of the main mechanisms is the droplet model that polyaromatic hydrocarbon molecules (PAH), which are formed in gas phase, play an important role in the nucleation and growth of PyC.…”

Section: Introductionmentioning

confidence: 99%

A layer-by-layer deposition mechanism for producing a pyrolytic carbon coating on carbon nanotubes

Zheng

Sano

Uchiyama

2013

Carbon

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Abstract:Pyrolytic carbon (PyC) was deposited on carbon nanotubes (CNTs) in order to modify them by introducing defects to their surface. The deposition of PyC was carried out at temperature between 800 and 1000ºC using propane as carbon source with or without a hydrogen carrier gas at low pressure of 20 kPa. The structure of PyC coatings was examined using transmission electron microscopy. The PyC coating could be distinguished from the original CNT walls due to the difference of the structure,with the coating showing a less orderly layer structure. When H 2 was introduced during deposition, PyC coating started to form at 900ºC, and the deposition rate increased rapidly with increasing temperature. Without H 2 , PyC coating with a thickness of a few layers could be formed at temperatures between 800-900ºC in 10 min. The outmost layer of the PyC coating showed a structure of rough and curved carbon fragment. A layer-by-layer mechanism is proposed for the deposition consisting of alternating fragment formation (nucleation) and lateral growth to layer.

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The Influence of Carbon Precursors on the Gas-Phase Chemistry of Titanium Carbide CVD

Persis¹,

Teyssandier²,

McDaniel

et al. 2002

Chem. Vap. Deposition

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The influence of carbon precursors, such as methane (CH 4 ), acetylene (C 2 H 2 ), and propane (C 3 H 8 ), on the gas-phase chemistry of the Ti-C-Cl-H system used to deposit titanium carbide (TiC) from titanium tetrachloride (TiCl 4 ) was investigated by calculating the thermodynamic equilibrium and modeling rate equations from a proposed kinetic model. Differences in the resultant gas-phase chemistries for reactions under reduced pressure at 1500 K are discussed. Initial mixtures of TiCl 4 , H 2 , and a hydrocarbon that produced identical equilibrium compositions were determined. Results for the Ti-C-Cl-H system for all three hydrocarbon precursors are compared to those of Ti-Cl-H and C-H in order to further illustrate the differences in thermal stability of key constituents, as well as the extent of conversion. Regardless of which carbon precursor is present, species belonging to the Ti-Cl-H subsystem are near equilibrium within 5 s. Conversely, species emanating from CH 4 decomposition in the Ti-C-Cl-H system are predicted to be far from equilibrium and unreactive with TiCl 4 . In contrast, the preponderant species under thermodynamic equilibrium, C 2 H 2 , provides a uniform source of carbon at any residence time. Finally, the stability of C 3 H 8 in the Ti-C-Cl-H system is significantly greater than in the C-H system. This greater stability is accompanied by a significant variation in the rate of by-product formation, suggesting that TiCl 4 and its subchlorides effectively compete with C 3 H 8 for important reactive intermediates. In the case of C 3 H 8 , a reaction flow analysis was carried out identifying the three main reaction paths that are responsible for propane decomposition, the further links that appear between these paths, and how the paths vary over time.

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Chemistry and kinetics of chemical vapor deposition of pyrocarbon — V influence of reactor volume/deposition surface area ratio

Cited by 50 publications

References 6 publications

CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

CVD in Hot Wall Reactors—The Interaction Between Homogeneous Gas-Phase and Heterogeneous Surface Reactions

A layer-by-layer deposition mechanism for producing a pyrolytic carbon coating on carbon nanotubes

The Influence of Carbon Precursors on the Gas-Phase Chemistry of Titanium Carbide CVD

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