Thermodynamics and kinetics for nucleation of diamond in the chemical vapor deposition process

Hwang, Nong M.; Bahng, Gun-Woong; Yoon, Duk N.

doi:10.1016/0925-9635(92)90023-h

Cited by 19 publications

(8 citation statements)

References 6 publications

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“…The problem of relative stability of various nanosize forms of carbon has attracted a lot of attention in the last 10−15 years. Theoretical analysis of size stability of different linear-, planar-, ring-, and sphere-shaped structural isomers as well as three-dimensional clusters with the diamond and graphitic structures − has shown that the size-dependent phase transformation is a distinctive feature of the nanoscale carbon system. Ring-shaped structures, in particular, are expected to be the most stable form of carbon clusters made of about 20 atoms .…”

Section: Introductionmentioning

confidence: 99%

Size-Dependent Phase Transition of Diamond to Graphite at High Pressures

et al. 2007

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Size-dependent phase transition of nanosize diamond particles (NDPs) to graphite was found in the course of studies of high pressure high temperature (HPHT) induced transformations of NDPs at 8 GPa and in the temperature range of 873−1623 K. Analysis of the products of HPHT treatment of powder NDPs (with the mean size of 4.5 nm) by X-ray diffraction (XRD), scanning (SEM) and transmission electron (TEM) microscopies, and Raman spectroscopy have shown that at 8 GPa the increase of the treatment temperature results in a gradual enlargement of NDPs. According to XRD data, the temperature increase from 873 to 1473 K at the treatment time of 60 s gives rise to NDP mean size enlargement from initial 4.5 to 8.8 nm. However, the largest NDPs can reach the sizes of 13.5−14.0 nm at 1473 K, as measured directly from TEM images. At 1623 K, size-dependent phase transition of diamond to graphite has been observed. By applying the Arrenius equation to the particle mean size versus treatment temperature plot, activation energy for the diamond solid phase growth at 8 GPa was calculated to be 112 ± 8 kJ/mol. The critical size of NDP corresponding to the point of phase transition at 8 GPa and 1623 K was estimated to be ∼18 nm. The likely effect of the size-dependent diamond-to-graphite phase transition on the process of diamond synthesis and, in particular, the problem of formation of critical seeds for crystal growth of macroscale diamond are discussed in the paper.

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Section: Introductionmentioning

confidence: 99%

Size-Dependent Phase Transition of Diamond to Graphite at High Pressures

et al. 2007

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“…However, for the nucleation of CVD diamond on nondiamond substrates, surface relaxation of diamond grains could affect the nucleation barrier energy . Moreover, the nucleation of CVD diamond is originally involved in the physical process. ,− Theoretically, thermodynamic nucleation has been validly employed to deal with diamond phase formation on nondiamond substrates upon CVD. − Experimentally, more experimental data implied that CVD diamond concerns physical nucleation. − Especially, Wang et al studied the heterogeneous nucleation of CVD diamond in experimental and thermodynamic in detail, and reported that the thermodynamic calculations were in good agreement with experimental data . Accordingly, thermodynamic nucleation could be valid in the formation of diamond phase on nondiamond substrates upon CVD.…”

Section: Introductionmentioning

confidence: 99%

“…5 Moreover, the nucleation of CVD diamond is originally involved in the physical process. 6,[12][13][14][15] Theoretically, thermodynamic nucleation has been validly employed to deal with diamond phase formation on nondiamond substrates upon CVD. [13][14][15] Experimentally, more experimental data implied that CVD diamond concerns physical nucleation.…”

Section: Introductionmentioning

confidence: 99%

“…6,[12][13][14][15] Theoretically, thermodynamic nucleation has been validly employed to deal with diamond phase formation on nondiamond substrates upon CVD. [13][14][15] Experimentally, more experimental data implied that CVD diamond concerns physical nucleation. [5][6] Especially, Wang et al studied the heterogeneous nucleation of CVD diamond in experimental and thermodynamic in detail, and reported that the thermodynamic calculations were in good agreement with experimental data.…”

Section: Introductionmentioning

confidence: 99%

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A Nanoscaled Thermodynamic Approach in Nucleation of CVD Diamond on Nondiamond Surfaces

et al. 2004

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Based on the carbon thermodynamic equilibrium phase diagram, a nanoscaled thermodynamic approach, taking the effect of nanosize-induced additional pressure on Gibbs free energy of diamond critical nuclei and phase transition probability from graphite to diamond into account, was performed to elucidate diamond nucleation on nondiamond surfaces upon chemical vapor deposition (CVD). The theoretical analysis showed that the capillary effect of the nanosize curvature of diamond critical nuclei could drive the metastable phase region of nucleation of CVD diamond into a new stable phase region in the carbon diagram. Consequently, diamond nucleation is preferable to graphite phase formation in competing growth of diamond and graphite upon CVD.

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“…Hwang et al [7,58] suggested that the essential role of gas activation is to generate an abundant amount of electric charge rather than atomic hydrogen and that the negative charge stabilizes diamond over graphite. They further suggested that charged diamond nanoparticles are generated in the gas phase, becoming the building blocks of diamond films.…”

Section: Non Classical Crystallization In Diamond Deposition At Low Pmentioning

confidence: 99%

Non-Classical Crystallization of Thin Films and Nanostructures in CVD Process

Jung¹,

Hwang²

2016

Chemical Vapor Deposition - Recent Advances and Applications in Optical, Solar Cells and Solid State Devices

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Non-classical crystallization, where crystals grow by the building blocks of nanoparticles, has become a significant issue not only in solution but also in the gas phase synthesis such as chemical vapor deposition (CVD). Recently, non-classical crystallization was observed in solution in-situ by transmission electron microscope (TEM) using a liquid cell technique. In various CVD processes, the generation of charged nanoparticles (CNPs) in the gas phase has been persistently reported. Many evidences supporting these CNPs to be the building blocks of thin films and nanostructures were reported. According to non-classical crystallization, many thin films and nanostructures which had been believed to grow by individual atoms or molecules turned out to grow by the building blocks of CNPs. The purpose of this paper is to review the development and the main results of non-classical crystallization in the CVD process. The concept of non-classical crystallization is briefly described. Further, it will be shown that the puzzling phenomenon of simultaneous diamond deposition and graphite etching, which violates the second law of thermodynamics when approached by classical crystallization, can be approached successfully by nonclassical crystallization. Then, various aspects of non-classical crystallization in the growth of thin films and nanostructures by CVD will be described.

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Thermodynamics and kinetics for nucleation of diamond in the chemical vapor deposition process

Cited by 19 publications

References 6 publications

Size-Dependent Phase Transition of Diamond to Graphite at High Pressures

Size-Dependent Phase Transition of Diamond to Graphite at High Pressures

A Nanoscaled Thermodynamic Approach in Nucleation of CVD Diamond on Nondiamond Surfaces

Non-Classical Crystallization of Thin Films and Nanostructures in CVD Process

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