Diamond growth using carbon monoxide as a carbon source

1992 ◽  
Vol 7 (5) ◽  
pp. 1195-1203 ◽  
Author(s):  
F.M. Cerio ◽  
W.A. Weimer ◽  
C.E. Johnson
Keyword(s):  
Carbon Source ◽  
Gas Phase ◽  
Growth Rates ◽  
Microwave Plasma ◽  
Polycrystalline Diamond ◽  
Chemical Mechanism ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Lower Growth ◽  
Temperature Combustion

Polycrystalline diamond films were produced in a microwave plasma assisted CVD reactor using CO as the carbon source gas. Reactor exhaust gas compositions were determined by mass spectrometry using 2–10% CO and 0–1.5% O2 in H2 feed gas mixtures. The chemistry involved in the gas phase is similar to that which occurs when diamond is grown using hydrocarbons as carbon source gases. A chemical mechanism for the oxidation of CH4 in flames appears to be applicable to this system. Addition of O2 to the reactor feed gas results in increased growth rates for low addition levels possibly due to activation of the diamond surface, while lower growth rates result at high addition levels due to oxidation of carbon from the surface and depletion of diamond growth precursors in the gas phase. The chemical reactions that take place in the plasma are similar to those that occur in flames and hot filament reactors, indicating that the plasma acts to induce reactions that are normally associated with high temperature combustion processes.

Polycrystalline Diamond Coating on Orthopaedic Implants: Realization, and Role of Surface Topology and Chemistry in Adsorption of Proteins and Cell Proliferation

2022 ◽  
Author(s):  
Justas Zalieckas ◽  
Ivan Rios Mondragon ◽  
Paulius Pobedinskas ◽  
Arne Skodvin Kristoffersen ◽  
Samih Mohamed-Ahmed ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Microwave Plasma ◽  
Polycrystalline Diamond ◽  
Surface Topology ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Type I ◽  
Diamond Coatings ◽  
Orthopaedic Implants

Polycrystalline diamond has the potential to improve the osseointegration of orthopaedic implants compared to conventional osteo-implant materials such as titanium. However, despite the excellent biocompatibility and superior mechanical properties, the major challenge of using diamond for implants such as those used for hip arthroplasty is the limitations of microwave plasma chemical vapor deposition (CVD) techniques to synthesize diamond on complex-shaped objects. Here, for the first time we demonstrate diamond growth on titanium acetabular shells using surface wave plasma CVD method. Polycrystalline diamond coatings were synthesized at low temperatures (~400 °C) on three types of acetabular shells with different surface structure and porosity. We achieved diamond growth on highly porous surfaces designed to mimic the structure of the trabecular bone and improve osseointegration. Biocompatibility was investigated on nanocrystalline diamond (NCD) and ultrananocrystalline diamond (UNCD) coatings terminated either with hydrogen or oxygen. To understand the role of diamond surface topology and chemistry in attachment and proliferation of mammalian cells we investigated adsorption of extracellular matrix (ECM) proteins, and monitored metabolic activity of fibroblasts, osteoblasts, and bone marrow-derived mesenchymal stem cells (MSCs). The interaction of bovine serum albumin (BSA) and Type I collagen with diamond surface was investigated by confocal fluorescence lifetime imaging microscopy (FLIM). We found that proliferation of MSCs was better on hydrogen terminated UNCD than on oxygen terminated counterpart. These findings corelate to the behaviour of collagen on diamond substrates observed by FLIM. Hydrogen terminated UNCD provides better adhesion and proliferation for MSCs, compared to titanium, while growth of fibroblasts is poorest on hydrogen terminated NCD and osteoblasts behave similarly on all tested surfaces. These results open new opportunities for application of diamond coatings on orthopaedic implants.

Simulations of CVD Diamond Film Growth: 2D Models for the identities and concentrations of gas-phase species adsorbing on the surface

2011 ◽  
Vol 1282 ◽  
Author(s):  
Paul W. May ◽  
Yuri A. Mankelevich
Keyword(s):  
Gas Phase ◽  
Film Growth ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Diamond Films ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Process Conditions ◽  
Ultrananocrystalline Diamond ◽  
Single Crystal Diamond

ABSTRACTA prerequisite for modelling the growth of diamond by CVD is knowledge of the identities and concentrations of the gas-phase species which impact upon the growing diamond surface. Two methods have been devised for the estimation of this information, and have been used to determine adsorption rates for CxHy hydrocarbons for process conditions that experimentally produce single-crystal diamond, microcrystalline diamond films, nanocrystalline diamond films and ultrananocrystalline diamond films. Both methods rely on adapting a previously developed model for the gas-phase chemistry occurring in a hot filament or microwave plasma reactor. Using these methods, the concentrations of most of the CxHy radical species, with the exception of CH3, at the surface have been found to be several orders of magnitude smaller than previously believed. In most cases these low concentrations suggest that reactions such as direct insertion of C1Hy (y = 0-2) and/or C2 into surface C–H or C–C bonds can be neglected and that such species do not contribute significantly to the diamond growth process in the reactors under study.

Structure formation in diamond powder during chemical infiltration from the gas phase

2020 ◽  
pp. 61-68
Author(s):  
S. A. Eremin ◽  
I. A. Leontiev ◽  
Yu. M. Yashnov ◽  
V. N. Anikin
Keyword(s):  
Structure Formation ◽  
Gas Phase ◽  
Microwave Plasma ◽  
Diamond Powder ◽  
Plasma Discharge ◽  
Diamond Growth ◽  
Infiltration Process ◽  
Allotropic Modifications ◽  
Gas Pumping ◽  
Carbon Modifications

In this paper was investigated effect of pumping a mixture of methane and hydrogen in a microwave discharge through layers of diamond powder on structure formation sediment during chemical infiltration from the gas phase. The infiltration process was implemented on the conditions of gas pumping through the layers of diamond powder, in the presence of a plasma discharge over the samples. It is established that in contempt of the size of the diamond powder, the growth of diamond from the gas phase occurs on the surface of the first layer, the growth of diamond from the gas phase stops when the second layer starts, and different allotropic modifications of carbon start to grow, in particular nanocrystalline graphite, carbon nanotubes, and graphite. Such a rapid transition between diamond growth and the growth of various allotropic carbon modifications is related with the screening of the plasma discharge by the first layer of diamond powder. Thus, the absence of direct contact of the microwave plasma discharge with the formed molecular hydrogen during its recombination leads to the fact that the concentration of atomic hydrogen is low to maintain the growth of diamond from the gas phase inside the layer of diamond powder.

Diamond Growth Rates and Quality: Dependence on Gas Phase Composition

1994 ◽  
Vol 339 ◽  
Author(s):  
William D. Cassidy ◽  
Edward A. Evans ◽  
Yaxin Wang ◽  
John C. Angus ◽  
Peter K. Bachmann ◽  
...  
Keyword(s):  
Growth Rates ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Gas Composition ◽  
Chemical Potentials ◽  
Co Concentration ◽  
The Stability ◽  
Hot Filament ◽  
Tie Line

ABSTRACTDiamond growth rates and quality were studied as a function of source gas composition and correlated with position on the ternary C-H-O diagram. The chemical potentials of carbon and oxygen change dramatically on either side of the H2-CO tie line, leading to large differences in the equilibrium distribution of species. These differences are reflected in the species flux reaching the diamond surface, and hence in the quality and growth rate of the diamond. In situ microbalance measurements in a hot-filament reactor show that the reaction rate is independent of the CO concentration, but decreases with increasing O2. Quality, as measured by Raman spectroscopy, increases as the C/C+O ratio in the source gases is reduced to approach the critical value of 0.5. The stability of the filaments to decarburizing and oxidation are correlated with the carbon and oxygen chemical potentials and hence to the position on the C-H-O diagram. A preliminary ternary diagram for the C-H-F system is presented.

Uncoupling crystal growth and nucleation in the deposition of diamond from the gas phase

1992 ◽  
Vol 7 (7) ◽  
pp. 1778-1787 ◽  
Author(s):  
E. Molinari ◽  
R. Polini ◽  
M.L. Terranova ◽  
P. Ascarelli ◽  
S. Fontana
Keyword(s):  
Gas Phase ◽  
Growth Rates ◽  
Diamond Surface ◽  
High Catalytic Activity ◽  
Fast Reaction ◽  
Sem Images ◽  
Atom Concentration ◽  
Hot Filament ◽  
Proper Consideration

Diamond deposits of well-separated particles have been obtained by the hot filament CVD technique on Si(100) wafers. Particle counting in SEM images and determination of their linear dimensions require a separate study of growth rates and of nucleation densities as a function of time, substrate temperature (500 °C–950 °C), gas phase composition (0.5–2% CH4 in H2), and total pressure (15–76 Torr). It is shown that recent models proposed for the growth process can successfully be applied if proper consideration is given to the high catalytic activity of the growing diamond surface for the heterogeneous recombination of gaseous H-atoms. This fast reaction controls the H-atom concentration at the surface and couples growth rates and nucleation densities via the gas phase.

GAS-PHASE SYNTHESIS OF DIAMOND STRUCTURES

2020 ◽  
Author(s):  
A. K. Rebrov ◽  
Keyword(s):  
Gas Phase ◽  
Building Material ◽  
Microwave Plasma ◽  
Diamond Surface ◽  
Gas Mixture ◽  
Diamond Synthesis ◽  
Phase Synthesis ◽  
Transfer Processes ◽  
Carbon Structures ◽  
Complex Influence

The diamond synthesis from vapor (gas) phase is realized under complex influence of nonequilibrium transfer processes in activated gas mixtures by formation of carbon structures on a nascent diamond surface. The microwave plasma generates an active gas mixture and fragments of building material are transported

Selective Growth of Polycrystalline Diamond Thin Films

1992 ◽  
Vol 282 ◽  
Author(s):  
R. Ramesham
Keyword(s):  
Plasma Etching ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Selective Growth ◽  
Diamond Growth ◽  
Nucleation Density ◽  
Substrate Type ◽  
Temperature Growth ◽  
Single Crystal Diamond

ABSTRACTMicrowave plasma assisted CVD is employed to grow diamond films using a gas mixture of H2 and CH4on various substrates. Diamond has a tendency not to nucleate growth on mirror-smooth finished substrates irrespective of the substrate type (except single crystal diamond). We have developed various processes to enhance the nucleation density of the diamond substantially by damaging or seeding the surface of the substrates. Several process techniques such as 1. silicon nitride and silicon dioxide process, 2. ultrasonic agitation process, 3. selective seeding of diamond by electroplating of Cu, 4. patterning of diamond films by air-microwave plasma etching, etc., were developed to achieve the patterns of diamond on various substrates. Selective growth of doped diamond and low temperature growth of diamond for microelectronic applications have also been achieved by using the above processes (1 and 2). Details on selective diamond growth processes and the morphology of as-deposited selective diamond by SEM are presented.

A mechanism for crystal twinning in the growth of diamond by chemical vapour deposition

2007 ◽  
Vol 366 (1863) ◽  
pp. 295-311 ◽  
Author(s):  
James E Butler ◽  
Ivan Oleynik
Keyword(s):  
Carbon Atom ◽  
Surface Morphology ◽  
Growth Rates ◽  
Vapour Deposition ◽  
Chemical Vapour ◽  
Polycrystalline Diamond ◽  
Diamond Growth ◽  
Subsequent Growth ◽  
Crystal Twinning ◽  
Morphology Changes

A model for the formation of crystal twins in chemical vapour deposited diamond materials is presented. The twinning mechanism originates from the formation of a hydrogen-terminated four carbon atom cluster on a local {111} surface morphology, which also serves as a nucleus to the next layer of growth. Subsequent growth proceeds by reaction at the step edges with one and two carbon atom-containing species. The model also provides an explanation for the high defect concentration observed in 〈111〉 growth sectors, the formation of penetration and contact twins, and the dramatic enhancement in polycrystalline diamond growth rates and morphology changes when small amounts of nitrogen are added to the plasma-assisted growth environments.

Diamond Growth on (a) Large Mo Cylinders at 30 Torr and (b) Flat Mo at One Atmospheric Pressure of H2 and CH4

1996 ◽  
Vol 441 ◽  
Author(s):  
R. Ramesham ◽  
M. F. Rose
Keyword(s):  
Atmospheric Pressure ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Polycrystalline Diamond ◽  
Diamond Growth ◽  
Single Filament ◽  
Active Length ◽  
Microwave Plasma Cvd ◽  
Hot Filament ◽  
First Time

Abstract(a) Polycrystalline diamond films have been grown on cylindrical Mo substrates by hot filament and microwave plasma CVD techniques using a gas mixture of hydrogen and methane. A single hot tungsten filament has been used to demonstrate the growth of adherent diamond films on large cylinders. To our knowledge this is the first report on such large cylindrical substrate (area: 41 cm2 ) using a single filament of active length of 3.75 cm. (b) Polycrystalline diamond films have been deposited by hot-filament technique for the first time using methane and hydrogen at an atmospheric pressure of hydrogen on flat substrates. The diamond growth has been performed at various pressures ranging from 34.5 to 750 Torr. The as-deposited films were analyzed by SEM and Raman to determine morphology and chemical nature, respectively.A. Growth of Diamond Film on Molybdenum Cylinders

Fracture strength measurement of filament assisted CVD polycrystalline diamond films

1992 ◽  
Vol 7 (6) ◽  
pp. 1432-1437 ◽  
Author(s):  
G.F. Cardinale ◽  
C.J. Robinson
Keyword(s):  
Fracture Strength ◽  
Microwave Plasma ◽  
Natural Diamond ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Polycrystalline Diamond ◽  
High Strength ◽  
Coarse Grained ◽  
Diamond Growth ◽  
Growth Surface

The fracture strength of polycrystalline diamond films deposited by filament assisted chemical vapor deposition in the thickness range of 3.5 to 160 μm is investigated. Using a burst pressure technique, the fracture strengths of circular diamond film specimens are calculated. An average fracture strength of 730 MPa for nine samples was computed. This value is in good agreement with published strengths of microwave plasma deposited diamond films, comparable to other high strength materials, and within an order of magnitude of the fracture strength of bulk natural diamond. The average fracture strength of the fine-grained substrate interface appears consistently higher than that of the coarse-grained diamond growth surface.

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