Studies of Diamond Growth Mechanisms in a Hot Filament Reactor

1989 ◽  
Vol 162 ◽  
Author(s):  
C. Judith Chu ◽  
Benjamin J. Bai ◽  
Mark P. D'Evelyn ◽  
Robert H. Hauge ◽  
John L. Margrave
Keyword(s):  
Growth Process ◽  
Total Concentration ◽  
Cvd Diamond ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Growth Mechanisms ◽  
Methyl Radical ◽  
Hydrocarbon Sources ◽  
Hot Filament ◽  
Heated Filament

ABSTRACTThe incorporation of methane into low-pressure CVD diamond thin films has been compared to that of acetylene. 13CH4 and 12C2 H2 were used as the hydrocarbon sources in a heated-filament CVD diamond growth process at a total concentration of 0.5% hydrocarbon in 99.5% hydrogen. Results indicated that methane and/or methyl radical is the dominant carbon source for diamond growth in a hot filament reactor under steady state conditions and that acetylene is rapidly hydrogenated to methane. Results also indicated that diamond surface reactions play an important role in determining the relative methane to acetylene ratios.

Adsorption of Hydrocarbon Radicals on the Hydrogenated Diamond Surface

1989 ◽  
Vol 162 ◽  
Author(s):  
Mark R. Pederson ◽  
Koblar A. Jackson ◽  
Warren E. Pickett
Keyword(s):  
Carbon Atom ◽  
Bond Length ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Dangling Bond ◽  
Methyl Radical ◽  
Acetylene Molecule ◽  
Bulk Diamond ◽  
Equilibrium Geometries ◽  
Insight Into

ABSTRACTIn order to gain insight into diamond growth, we have calculated equilibrium geometries for several adsorbates on the hydrogenated diamond <111> surface. While the adsorption height of a single methane radical onto a dangling bond is found to be in excellent agreement with the bulk-diamond bond length, the back bonded hydrogens of adjacent adsorbed methyl radicals repel one another. In contrast, adjacent acetlyinic radicals do not repel one another but lead to the introduction of double carbon bonds, misplaced carbon atoms above the active layer and a bond length which is too short in comparison to that of bulk diamond. Our calculations on the acetylene molecule near a dangling bond indicate that the resulting adsorbate bond length is substantially too large and that the carbon atom is unlikely to be stable directly above the surface carbon atom. Of the adsorbates studied, geometrical arguments suggest that the methyl radical is likely to be the most ideal adsorbate.

The Role of Heavy Hydrocarbons in Cvd Diamond Growth

1992 ◽  
Vol 270 ◽  
Author(s):  
Ching-Hsong Wu ◽  
T. J. Potter ◽  
M. A. Tamor
Keyword(s):  
Growth Rate ◽  
Cvd Diamond ◽  
Diamond Growth ◽  
Spectrometric Analysis ◽  
Heavy Hydrocarbons ◽  
Hot Filament Cvd ◽  
Hot Filament ◽  
Deposition Conditions

ABSTRACTA mass spectrometric analysis of heavy hydrocarbons (HHCs) during hot-filament CVD diamond growth was performed together with in situ monitoring of the growth rate. Many HHCs were detected and tentatively identified. Of all HHCs studied, only diacetylene shows good correlation with the diamond growth rate under various deposition conditions. Its possible role is discussed.

Diamond Homoepitaxy Kinetics: Growth, Etching, and the Role of Oxygen

1994 ◽  
Vol 339 ◽  
Author(s):  
Robin E. Rawles ◽  
Mark P. D'Evelyn
Keyword(s):  
Temperature Dependence ◽  
High Temperatures ◽  
Low Temperatures ◽  
Diamond Surface ◽  
Diamond Growth ◽  
Minimal Amount ◽  
Rate Behavior ◽  
Etch Rates ◽  
Apparent Activation Energies ◽  
Hot Filament

ABSTRACTGrowth and etch rates for diamond homoepitaxy have been measured in situ using Fizeau interferometry. Experiments were conducted in a hot-filament reactor using hydrogen, methane, and oxygen feed gases at a reactor pressure of 25 torr. The substrate temperature dependence for growth on diamond(lOO) was studied for 0.5% and 1% CH4 and 0–0.44% O2. Apparent activation energies of 17 and 5 kcal/mol were determined for growth from 0.5% and 1% CH4 in hydrogen, over the ranges of 700 – 1000 °C and 800 – 1050 °C, respectively. When a minimal amount of Oxygen was added to the feedstock, the growth-rate behavior was similar for that with pure methane. With greater amounts of added oxygen, growth rates were higher than those without Oxygen at low temperatures, proceeded through a maximum, and then decreased until etching was observed at high temperatures. Similar behavior was observed for growth from 1% CH4 with and without oxygen. We also measured the temperature dependence for etching of homoepitaxial diamond films in hydrogen with 0–0.1% O2, and observed etch rates of 0.01 – 0.1 microns/hr in the range of 950 – 1150 °C. We propose that oxygen facilitates diamond growth at low temperatures by enhancing the removal of both sp2- and sp3-bonded “errors” and/or by increasing the efficiency of carbon incorporation by roughening the diamond surface, and that these etching processes become dominant at high temperatures.

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.

scholarly journals CVD diamond growth mechanisms as identified by surface topography

1993 ◽  
Vol 2 (5-7) ◽  
pp. 997-1003 ◽  
Author(s):  
W.J.P. van Enckevort ◽  
G. Janssen ◽  
W. Vollenberg ◽  
J.J. Schermer ◽  
L.J. Giling ◽  
...  
Keyword(s):  
Surface Topography ◽  
Cvd Diamond ◽  
Diamond Growth ◽  
Growth Mechanisms

Diamond CVD Growth Mechanisms and Reaction Rates From First-Principles

2000 ◽  
Vol 616 ◽  
Author(s):  
I.I Oleinik ◽  
D.G. Pettifor ◽  
A.P. Sutton ◽  
C.C. Battaile ◽  
D.J. Srolovitz ◽  
...  
Keyword(s):  
Monte Carlo ◽  
First Principles ◽  
Kinetic Monte Carlo ◽  
Experimental Studies ◽  
Cvd Diamond ◽  
Reaction Rates ◽  
Diamond Growth ◽  
Growth Mechanisms ◽  
Monte Carlo Studies ◽  
Cvd Growth

AbstractCVD diamond is an enabling material for diverse applications. In recent years, multiscale modelling of CVD growth in conjunction with experimental studies of the deposition processes has made a substantial progress towards our understanding of the fundamental growth chemistry and material quality. Macroscopic gas phase simulations of the CVD reactor, the mesoscale kinetic Monte-Carlo (KMC) modelling of the crystal growth and nanoscale modelling of the surface chemistry are three main legs in the multiscale hierarchy. In the framework of this methodology we have performed first-principles quantum mechanical calculations of bonding and reaction kinetics of the elementary growth processes and provided critical input in the form of atomistic growth mechanisms and reaction rates for the mesoscale KMC modelling of CVD diamond growth. A key success was achieved by combining first-principles and Monte Carlo studies to elucidate (100) growth mechanisms that have perplexed the diamond growth community for many years.

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