Charge-transfer doped intrinsic diamond electrochemical electrodes

2011 ◽  
Vol 1362 ◽  
Author(s):  
Waileong Chen ◽  
Chiuan-Yi Li ◽  
Shoupu Yeh ◽  
Shin-Hung Yei ◽  
Yonhua Tzeng
Keyword(s):  
Aqueous Solution ◽  
Charge Transfer ◽  
Microwave Plasma ◽  
High Current Density ◽  
Diamond Films ◽  
Diamond Surface ◽  
Pure Hydrogen ◽  
Electrochemical Characteristics ◽  
Air Plasma ◽  
Hydrogen Atoms

ABSTRACTWe report electrochemical characteristics of hydrogen terminated charge-transfer doped intrinsic microcrystalline diamond films. Microcrystalline diamond was synthesized by Direct- Current Plasma Enhanced Chemical Vapor Deposition (DC-PECVD) in methane diluted by hydrogen. The diamond films were subjected to further treatment by microwave plasma in pure hydrogen to increase the hydrogen termination of the diamond surfaces and their negative electron affinity. When the diamond is exposed to the ambient moisture, valance electrons tend to tunnel from the first few atomic layers of the diamond surface to the adsorbed water adlayer. This charge transfer process results in the surface of hydrogen-terminated diamond behaving like a p-type semiconductor.Electrochemical characteristics of hydrogen-terminated diamond films were exposed to an air plasma for depleting the surface hydrogen atoms and then re-hydrogenated the same diamond films with atomic hydrogen. Cyclic voltammetry in 0.1M H2S04 aqueous solution and 0.01M Fe(CN)6-4/-3+0.1M KCl aqueous solution was applied to reveal high current density and wide potential window for hydrogen-terminated diamond grown on silicon substrates. The faceted surface morphology has been observed by SEM. The crystalline characteristics and carbon phases in the diamond film were examined by Raman spectroscopy.

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.

scholarly journals A self-boosting microwave plasma strategy tuned by air pressure for the highly efficient and controllable surface modification of carbon

RSC Advances ◽  
2021 ◽  
Vol 11 (17) ◽  
pp. 9955-9963
Author(s):  
Yanjing Liu ◽  
Jiawei He ◽  
Bing Zhang ◽  
Huacheng Zhu ◽  
Yang Yang ◽  
...  
Keyword(s):  
Surface Modification ◽  
Carbon Fiber ◽  
High Efficiency ◽  
Microwave Plasma ◽  
Air Pressure ◽  
Air Plasma ◽  
Highly Efficient ◽  
Carbon Fiber Cloth

Microwave enabled air plasma was boosted by a carbon fiber cloth (CFC) and used for the high-efficiency surface modification of the CFC, yielding CFCs with tunable contents of oxygen and each O-containing group.

scholarly journals Effect of Nitrogen on the Growth of (100)-, (110)-, and (111)-Oriented Diamond Films

2020 ◽  
Vol 11 (1) ◽  
pp. 126
Author(s):  
Jen-Chuan Tung ◽  
Tsung-Che Li ◽  
Yen-Jui Teseng ◽  
Po-Liang Liu
Keyword(s):  
Growth Mechanism ◽  
Density Functional ◽  
Film Growth ◽  
Hydrogen Abstraction ◽  
Diamond Films ◽  
Activation Energies ◽  
Diamond Surface ◽  
Nitrogen Doped ◽  
Nitrogen Substitution ◽  
Diamond Film Growth

The aim of this research is the study of hydrogen abstraction reactions and methyl adsorption reactions on the surfaces of (100), (110), and (111) oriented nitrogen-doped diamond through first-principles density-functional calculations. The three steps of the growth mechanism for diamond thin films are hydrogen abstraction from the diamond surface, methyl adsorption on the diamond surface, and hydrogen abstraction from the methylated diamond surface. The activation energies for hydrogen abstraction from the surface of nitrogen-undoped and nitrogen-doped diamond (111) films were −0.64 and −2.95 eV, respectively. The results revealed that nitrogen substitution was beneficial for hydrogen abstraction and the subsequent adsorption of methyl molecules on the diamond (111) surface. The adsorption energy for methyl molecules on the diamond surface was generated during the growth of (100)-, (110)-, and (111)-oriented diamond films. Compared with nitrogen-doped diamond (100) films, adsorption energies for methyl molecule adsorption were by 0.14 and 0.69 eV higher for diamond (111) and (110) films, respectively. Moreover, compared with methylated diamond (100), the activation energies for hydrogen abstraction were by 0.36 and 1.25 eV higher from the surfaces of diamond (111) and (110), respectively. Growth mechanism simulations confirmed that nitrogen-doped diamond (100) films were preferred, which was in agreement with the experimental and theoretical observations of diamond film growth.

scholarly journals Evolution of High-Quality Homoepitaxial CVD Diamond Films Induced by Methane Concentration

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 888
Author(s):  
Pengfei Zhang ◽  
Weidong Chen ◽  
Longhui Zhang ◽  
Shi He ◽  
Hongxing Wang ◽  
...  
Keyword(s):  
Methane Concentration ◽  
Flat Surface ◽  
Microwave Plasma ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Plasma Chemical ◽  
High Quality ◽  
Effect Analysis ◽  
Plasma Chemical Vapor Deposition ◽  
Atomically Flat

In this paper, we successfully synthesized homoepitaxial diamond with high quality and atomically flat surface by microwave plasma chemical vapor deposition. The sample presents a growth rate of 3 μm/h, the lowest RMS of 0.573 nm, and the narrowest XRD FWHM of 31.32 arcsec. An effect analysis was also applied to discuss the influence of methane concentration on the diamond substrates.

Nano-Crystalline Diamond Films Deposited on Copper Substrate by MPCVD Method

2011 ◽  
Vol 117-119 ◽  
pp. 1310-1314
Author(s):  
Xing Rui Li ◽  
Xin Wei Shi ◽  
Ning Yao ◽  
Xin Chang Wang
Keyword(s):  
Diamond Film ◽  
Deposition Time ◽  
Microwave Plasma ◽  
Copper Substrate ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Annealing Process ◽  
Adhesive Properties ◽  
Plasma Chemical Vapor Deposition ◽  
Nano Crystalline

Nano-crystalline diamond (NCD) films with good adhesion were deposited on flexible copper substrate with Ni interlayer by Microwave Plasma Chemical Vapor Deposition (MPCVD). In this paper, two-stage method was used to improve the adhesion between the copper substrates and the diamond films. The effect of deposition time of the first stage on the morphology, crystal structure, non-diamond phase and adhesive properties of diamond films was investigated. The performance and structure of the diamond films were studied by Scanning Electron Microscope (SEM), Raman Spectroscopy (Raman) and X-Ray Diffraction (XRD). The results showed that the films were nano-crystalline diamond films positively. Impress method was used to examine the adhesion between diamond film and the substrate. When deposition time is 1.5h, the adhesion between diamond film and the copper substrate is better than the others. When it was 2.5h or longer, because the graphite layers existed as intermediate, the adherence between the diamond films and copper substrates was very poor. Therefore, the diamond films were easily peeled off from the substrates. Otherwise, the second stage called annealing process after the deposition played an important role to the adhesion. The films would be easily peeled off by curling without the annealing process.

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.

Characterization of diamond thin films: Diamond phase identification, surface morphology, and defect structures

1989 ◽  
Vol 4 (2) ◽  
pp. 373-384 ◽  
Author(s):  
B. E. Williams ◽  
J. T. Glass
Keyword(s):  
Electron Microscopy ◽  
Surface Morphology ◽  
Methane Concentration ◽  
Microwave Plasma ◽  
Defect Density ◽  
Diamond Films ◽  
Hydrogen Gas ◽  
Phase Identification ◽  
Diamond Crystals ◽  
Thin Carbon

Thin carbon films grown from a low pressure methane-hydrogen gas mixture by microwave plasma enhanced CVD have been examined by Auger electron spectroscopy, secondary ion mass spectrometry, electron and x-ray diffraction, electron energy loss spectroscopy, and electron microscopy. They were determined to be similar to natural diamond in terms of composition, structure, and bonding. The surface morphology of the diamond films was a function of position on the sample surface and the methane concentration in the feedgas. Well-faceted diamond crystals were observed near the center of the sample whereas a less faceted, cauliflower texture was observed near the edge of the sample, presumably due to variations in temperature across the surface of the sample. Regarding methane concentration effects, threefold {111} faceted diamond crystals were predominant on a film grown at 0.3% CH4 in H2 while fourfold {100} facets were observed on films grown in 1.0% and 2.0% CH4 in H2. Transmission electron microscopy of the diamond films has shown that the majority of diamond crystals have a very high defect density comprised of {111} twins, {111} stacking faults, and dislocations. In addition, cross-sectional TEM has revealed a 50 Å epitaxial layer of β3–SiC at the diamond-silicon interface of a film grown with 0.3% CH4 in H2 while no such layer was observed on a diamond film grown in 2.0% CH4 in H2.

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