Chemical Reaction Mechanisms of Diamond Growth

1994 ◽  
Vol 339 ◽  
Author(s):  
Michael Frenklach
Keyword(s):  
Chemical Vapor ◽  
Underlying Mechanism ◽  
Diamond Growth ◽  
Insertion Reaction ◽  
Hydrogen Atoms ◽  
Mediating Role ◽  
Current State ◽  
Surface Migration ◽  
Chemical Reaction Mechanisms ◽  
Diamond Chemical Vapor Deposition

ABSTRACTIt is becoming increasingly apparent that future progress in diamond chemical vapor deposition depends on deeper understanding of the underlying mechanism of surface processes. Substantial efforts toward this goal have led to several conclusions on which consensus is beginning to emerge. Among them are the mediating role of hydrogen atoms, generic features of the growth kinetics, thermodynamic stability of reconstructed (100) surfaces, and the insertion reaction of methyl into (100)-(2×l) dimers. Despite these efforts, an overall picture of diamond growth in terms of elementary processes is still lacking. In this paper, the current state of mechanistic understanding is reviewed, emphasizing common themes, and new results are presented. Among the latter are the effect of reaction reversibility on surface morphology, surface migration, and a new mechanism for diamond growth from acetylene.

scholarly journals Point defect incorporation during diamond chemical vapor deposition

1999 ◽  
Vol 14 (8) ◽  
pp. 3439-3446 ◽  
Author(s):  
C. C. Battaile ◽  
D. J. Srolovitz ◽  
J. E. Butler
Keyword(s):  
Growth Rate ◽  
Substrate Temperature ◽  
Kinetic Monte Carlo ◽  
Chemical Vapor ◽  
Atomic Scale ◽  
Diamond Growth ◽  
Gas Composition ◽  
Atom Concentration ◽  
Kinetic Monte Carlo Simulations ◽  
Diamond Chemical Vapor Deposition

The incorporation of vacancies, H atoms, and sp2 bond defects into single-crystal homoepitaxial (100) (2 × 1)–and (111)-oriented chemical-vapor-deposited diamond was simulated by atomic-scale kinetic Monte Carlo. Simulations were performed for substrate temperatures from 600 to 1200 °C with 0.4% CH4 in the feed gas, and for 0.4–7% CH4 feeds with a substrate temperature of 800 °C. The concentrations of incorporated H atoms increased with increasing substrate temperature and feed gas composition, and sp2 bond trapping increased with increasing feed gas composition. Vacancy concentrations were low under all conditions. The ratio of growth rate to H atom concentration was highest around 800–900°C, and the growth rate to sp2 ratio was maximum around 1% CH4, suggesting that these conditions are ideal for economical diamond growth under simulated conditions.

A One-Dimensional Stochastic Model of Diamond Growth

1995 ◽  
Vol 399 ◽  
Author(s):  
Michael Frenklach
Keyword(s):  
Critical Role ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Stochastic Simulations ◽  
Diamond Growth ◽  
Elementary Processes ◽  
One Dimensional ◽  
Surface Migration ◽  
Kinetic Rates

ABSTRACT(1+1)-dimensional stochastic simulations were performed representing elementary processes underlying chemical vapor deposition of diamond films. The results exhibit different growth regimes, depending on the values assigned to kinetic rates, and generally support the critical role of surface migration suggested earlier for the growth of diamond.

Low Pressure Diamond Growth Using a Secondary Radical Source

1992 ◽  
Vol 282 ◽  
Author(s):  
Terttu I. Hukka ◽  
Robin E. Rawles ◽  
Mark P. D'Evelyn
Keyword(s):  
Substrate Surface ◽  
Thermal Dissociation ◽  
Chemical Vapor ◽  
Atomic Layer ◽  
Atomic Layer Epitaxy ◽  
Diamond Growth ◽  
Hydrogen Atoms ◽  
Cycle Times ◽  
Novel Method ◽  
Precursor Molecules

ABSTRACTA novel method for chemical vapor deposition and atomic layer epitaxyusing radical precursors under medium vacuum conditions is being developed. Fluorine atoms are generated by thermal dissociation in a hot tube and abstract hydrogen atoms from precursor molecules injected immediately downstream of the source, generating radicals with completechemical specificity. The radical precursors are then transported to the growing substrate surface under nearly collision-free conditions. To date we have grown diamond films from CCl3 or CH3 radicals together with atomic hydrogen, generated by injecting CHCI3 or CH4 and H2 into the F atom stream at reactor pressures between 10−4 and 10−2 Torn This approach should be ideal for low-temperature growth and atomic layer epitaxy: growth rates remain relatively high because activation energies for radical reactions are typically small and because the cycle times for atomic layer epitaxy can be reduced to die msec range by fast gas-stream switching, and contamination and segregation are minimized by keeping the surface “capped” by chemisorbed intermediates.

scholarly journals Deposition of Boron-Doped Thin CVD Diamond Films from Methane-Triethyl Borate-Hydrogen Gas Mixture

Processes ◽  
2020 ◽  
Vol 8 (6) ◽  
pp. 666 ◽  
Author(s):  
Nikolay Ivanovich Polushin ◽  
Alexander Ivanovich Laptev ◽  
Boris Vladimirovich Spitsyn ◽  
Alexander Evgenievich Alexenko ◽  
Alexander Mihailovich Polyansky ◽  
...  
Keyword(s):  
Film Growth ◽  
Chemical Vapor ◽  
Hydrogen Gas ◽  
Diamond Growth ◽  
Structural Defects ◽  
Boron Doped Diamond ◽  
Diamond Deposition ◽  
Synthesis Conditions ◽  
Surface Etching ◽  
Boron Doped

Boron-doped diamond is a promising semiconductor material that can be used as a sensor and in power electronics. Currently, researchers have obtained thin boron-doped diamond layers due to low film growth rates (2–10 μm/h), with polycrystalline diamond growth on the front and edge planes of thicker crystals, inhomogeneous properties in the growing crystal’s volume, and the presence of different structural defects. One way to reduce structural imperfection is the specification of optimal synthesis conditions, as well as surface etching, to remove diamond polycrystals. Etching can be carried out using various gas compositions, but this operation is conducted with the interruption of the diamond deposition process; therefore, inhomogeneity in the diamond structure appears. The solution to this problem is etching in the process of diamond deposition. To realize this in the present work, we used triethyl borate as a boron-containing substance in the process of boron-doped diamond chemical vapor deposition. Due to the oxygen atoms in the triethyl borate molecule, it became possible to carry out an experiment on simultaneous boron-doped diamond deposition and growing surface etching without the requirement of process interruption for other operations. As a result of the experiments, we obtain highly boron-doped monocrystalline diamond layers with a thickness of about 8 μm and a boron content of 2.9%. Defects in the form of diamond polycrystals were not detected on the surface and around the periphery of the plate.

scholarly journals Unusual Dependence of the Diamond Growth Rate on the Methane Concentration in the Hot Filament Chemical Vapor Deposition Process

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 426
Author(s):  
Byeong-Kwan Song ◽  
Hwan-Young Kim ◽  
Kun-Su Kim ◽  
Jeong-Woo Yang ◽  
Nong-Moon Hwang
Keyword(s):  
Growth Rate ◽  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Methane Concentration ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Lower Growth ◽  
Filament Temperature ◽  
Diamond Phase ◽  
Hot Filament

Although the growth rate of diamond increased with increasing methane concentration at the filament temperature of 2100 °C during a hot filament chemical vapor deposition (HFCVD), it decreased with increasing methane concentration from 1% CH4 –99% H2 to 3% CH4 –97% H2 at 1900 °C. We investigated this unusual dependence of the growth rate on the methane concentration, which might give insight into the growth mechanism of a diamond. One possibility would be that the high methane concentration increases the non-diamond phase, which is then etched faster by atomic hydrogen, resulting in a decrease in the growth rate with increasing methane concentration. At 3% CH4 –97% H2, the graphite was coated on the hot filament both at 1900 °C and 2100 °C. The graphite coating on the filament decreased the number of electrons emitted from the hot filament. The electron emission at 3% CH4 –97% H2 was 13 times less than that at 1% CH4 –99% H2 at the filament temperature of 1900 °C. The lower number of electrons at 3% CH4 –97% H2 was attributed to the formation of the non-diamond phase, which etched faster than diamond, resulting in a lower growth rate.

scholarly journals A First-Principles Study of Hydrogen Desorption from High Entropy Alloy TiZrVMoNb Hydride Surface

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 553
Author(s):  
Jinjing Zhang ◽  
Jutao Hu ◽  
Haiyan Xiao ◽  
Huahai Shen ◽  
Lei Xie ◽  
...  
Keyword(s):  
Density Functional ◽  
Underlying Mechanism ◽  
Hydrogen Desorption ◽  
High Entropy Alloy ◽  
Hydrogen Atoms ◽  
Desorption Process ◽  
High Entropy ◽  
The Density Functional Theory ◽  
Hydride Hydrogen ◽  
Atomic States

The desorption behaviors of hydrogen from high entropy alloy TiZrVMoNb hydride surface have been investigated using the density functional theory. The (110) surface has been determined to be the most preferable surface for hydrogen desorption from TiZrVMoNb hydride. Due to the high lattice distortion and heterogeneous chemical environment in HEA hydride, hydrogen desorption from the HEA hydride surface is found to be complex. A comparison of molecular and atomic hydrogen desorption reveals that hydrogen prefers to desorb in atomic states from TiZrVMoNb hydride (110) surface rather than molecular states during the hydrogen desorption process. To combine as H2 molecules, the hydrogen atoms need to overcome attractive interaction from TiZrVMoNb hydride (110) surface. These results suggest that the hydrogen desorption on TiZrVMoNb hydride (110) surface is a chemical process. The presented results provide fundamental insights into the underlying mechanism for hydrogen desorption from HEA hydride surface and may open up more possibilities for designing HEAs with excellent hydrogen desorption ability.

Effects of social attachment on social media continuous usage intention: The mediating role of affective commitment

2020 ◽  
pp. 1-13
Author(s):  
Maosheng Yang ◽  
Shangui Hu ◽  
Bagna Essohanam Kpandika ◽  
Lei Liu
Keyword(s):  
Social Media ◽  
Structural Equation ◽  
Affective Commitment ◽  
Underlying Mechanism ◽  
Equation Model ◽  
Three Dimensions ◽  
Future Research ◽  
Social Attachment ◽  
Mediating Role ◽  
Continuous Usage Intention

BACKGROUND: Social attachment has been identified as a key antecedent motivating users’ social media involvement. However, there is a scarcity of research investigating whether and how three dimensions of social attachment exert impacts on users’ continuous usage intention of social media. OBJECTIVE: Based on structural equation model analysis, the current research clarifies the relationships between social attachment, affective commitment and social media continuous usage intention, which unveils the underlying mechanism through which three dimensions of social attachment influence users’ continuous usage intention of social media. METHODS: A survey was conducted with 536 informative responses obtained from TikTok public users for hypothesis testing analysis. RESULTS: Results indicate that three dimensions of social attachment (social connections, social dependence and social identity) are all positively related to users’ continuous usage intention of social media. Affective commitment partially mediates the relationship between social attachment and users’ continuous usage intention of social media. CONCLUSIONS: The current research makes an in-depth study about the underlying mechanism whereby social attachment exerts impacts on social media continuous usage intentionand provides several managerial and theoretical implications. Future research directions are discussed as well.

Kinetic Monte Carlo Simulation of Diamond Film Growth with the Inclusion of Surface Migration

1998 ◽  
Vol 527 ◽  
Author(s):  
Armando Netto ◽  
Michael Frenklach
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Film Growth ◽  
Kinetic Monte Carlo ◽  
Diamond Films ◽  
State Theory ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Gaseous Species ◽  
Surface Migration

ABSTRACTDiamond films are of interest in many practical applications but the technology of producing high-quality, low-cost diamond is still lacking. To reach this goal, it is necessary to understand the mechanism underlying diamond deposition. Most reaction models advanced thus far do not consider surface diffusion, but recent theoretical results, founded on quantum-mechanical calculations and localized kinetic analysis, highlight the critical role that surface migration may play in growth of diamond films. In this paper we report a three-dimensional time-dependent Monte Carlo simulations of diamond growth which consider adsorption, desorption, lattice incorporation, and surface migration. The reaction mechanism includes seven gas-surface, four surface migration, and two surface-only reaction steps. The reaction probabilities are founded on the results of quantum-chemical and transition-state-theory calculations. The kinetic Monte Carlo simulations show that, starting with an ideal {100}-(2×1) reconstructed diamond surface, the model is able to produce a continuous film growth. The smoothness of the growing film and the developing morphology are shown to be influenced by rate parameter values and by deposition conditions such as temperature and gaseous species concentrations.

Diamond Growth by Dual Hollow Cathode Arc Chemical Vapor Deposition

1997 ◽  
Vol 36 (Part 2, No. 10B) ◽  
pp. L1406-L1409 ◽  
Author(s):  
Gou-Tsau Liang ◽  
Franklin Chau-Nan Hong
Keyword(s):  
Chemical Vapor Deposition ◽  
Hollow Cathode ◽  
Vapor Deposition ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Cathode Arc
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