Nanoparticles generated by combining hot wall and microwave plasma chemical vapor synthesis

MRS Advances ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 213-218
Author(s):  
Alexander Levish ◽  
Markus Winterer
Keyword(s):  
Iron Oxide ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Process Window ◽  
Chemical Vapor Synthesis ◽  
Second Stage ◽  
Structure Surface ◽  
Oxide Phases ◽  
Precursor Decomposition

ABSTRACTControlling the oxidation state of iron and the crystal structure of iron containing compounds is the key to improved materials such as iron oxide nanoparticles for cancer treatment or heterogeneous catalysis. Iron oxides contain iron in different oxidation states and form different phases for one valence state (α-Fe3+2O2-3, β- Fe3+2O-32, etc.). Chemical vapor synthesis (CVS) allows the reproducible production of pure nanocrystals with narrow size distribution where particle formation and growth take place in the gas phase. Through the controlled variation of synthesis parameters CVS enables the synthesis of diverse iron oxide phases. In this study the energy for the CVS process is supplied by a hot wall furnace and a microwave plasma. The advantage of an plasma reactor as the first CVS stage is the fast and complete precursor decomposition at low temperatures. This results in a larger process window for the hot wall reactor in the second stage. The nanoparticles are examined regarding their structure, surface and valence by XRD and TEM.

Numerical Simulation of Gas Phase Growth Environment of Carbon Nanotube Synthesis by Plasma-Enhanced Chemical Vapor Deposition

2005 ◽  
Author(s):  
R. K. Garg ◽  
J. P. Gore ◽  
T. S. Fisher
Keyword(s):  
Gas Phase ◽  
Reaction Mechanisms ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Chemical Vapor ◽  
Synthesis Process ◽  
Phase Reaction ◽  
Phase Growth ◽  
Growth Environment ◽  
Hydrogen Mixture

The gas-phase growth environment of carbon nanotubes has been simulated using different published chemical reaction mechanisms for a gas mixture of methane and hydrogen. Detailed chemical analysis of the growth environment is important in identifying precursor species responsible for CNT formation and is useful in understanding fundamental mechanisms that ultimately could allow control of the CNT synthesis process. The present simulations seek to compare the roles of different gas phase reaction mechanisms and to identify precursors for CNT formation. The results show that inlet methane-hydrogen mixture converts primarily to a acetylene-hydrogen mixture, and C2H2, CH3, H2, and H are the main precursors formed in the plasma under experimentally verified CNT growth conditions in a microwave plasma reactor.

Characterization and Tribological Properties of Nanostructured Copper/Carbon Composite Films Prepared by Microwave Plasma-Assisted Dual Deposition Processes

2002 ◽  
Vol 750 ◽  
Author(s):  
François Thiery ◽  
Yves Pauleau ◽  
Jacques Pelletier
Keyword(s):  
Amorphous Carbon ◽  
Electron Cyclotron Resonance ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Composite Films ◽  
Chemical Vapor ◽  
Carbon Matrix ◽  
Carbon Composite ◽  
Carbon Films ◽  
Radius Of Curvature

ABSTRACTNanocrystalline copper/hydrogenated amorphous carbon films have been deposited on Si substrates at the floating potential using a distributed electron cyclotron resonance microwave plasma reactor. In this deposition technique, the microwave plasma-enhanced chemical vapor deposition process of carbon from argon-methane or argon-acetylene mixtures of various compositions was associated with the sputter deposition of copper from a copper target. The total pressure was fixed at 0.13 Pa. For deposition, the substrates mounted on a water-cooled substrate holder were maintained at ambient temperature. The composition of films determined by Rutherford backscattering spectroscopy, energy recoil detection analyses and nuclear reaction analyses was investigated as a function of the gas phase composition. The structure of films was identified by X-ray diffraction (XRD) techniques and the size of copper crystallites incorporated in the amorphous carbon matrix was deduced from XRD data. The magnitude of residual stresses developed in these films was calculated from the radius of curvature of film/substrate samples determined by profilometry. The residual stress values were found to be nearly independent on the composition of films and deposition parameters.

Synthesis of Metal Oxide Hollow Nanoparticles by Chemical Vapor Condensation Process

2006 ◽  
Vol 317-318 ◽  
pp. 219-222 ◽  
Author(s):  
C.W. Lee ◽  
S.G. Kim ◽  
Jai Sung Lee
Keyword(s):  
Iron Oxide ◽  
Reaction Temperature ◽  
Chemical Vapor ◽  
Phase Evolution ◽  
Vapor Condensation ◽  
Condensation Process ◽  
Iron Oxide Particles ◽  
Hollow Nanoparticles ◽  
Chemical Vapor Condensation ◽  
Oxide Phases

The influence of reaction temperature on phase evolution of iron oxide hollow nanoparticles during chemical vapor condensation (CVC) process using iron acetylacetonate was investigated. X-ray diffraction (XRD) analyses revealed that three iron oxide phases (α-Fe2O3, γ-Fe2O3, and Fe3O4) and a mixture of β-Fe2O3 and small amount of γ-Fe2O3 were synthesized at 700oC and 900oC, respectively. TEM observation disclosed that the iron oxide particles are almost composed of hollow structured nanoparticles of 10~20 nm in size and 3~5 nm in shell thickness. This result implies that reaction temperature determining various reaction parameters plays an important role for the phase- and structural evolutions of iron oxide hollow nanoparticles. Especially, the present investigation attempted to explain temperature dependence of the phase evolution of β-Fe2O3 hollow nanoparticles in association with the decomposition of iron acetylacetonate.

Effect of Two-Step Deposition Process on Morphology and Optical Properties of Nanostructured Diamond Films

2013 ◽  
Vol 651 ◽  
pp. 148-153 ◽  
Author(s):  
S. Tipawan Khlayboonme ◽  
Wicharn Techitdheera ◽  
Warawoot Thowladda
Keyword(s):  
Optical Properties ◽  
Carbon Content ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Deposition Process ◽  
Single Step ◽  
Second Step ◽  
Step Process

The morphology and optical properties of nanostructured diamond films affected by the two-step deposition process with changing CH4 concentration were investigated. The CH4 concentration was 1% for the first step and 2% for the second step. The films were prepared by chemical vapor deposition in a microwave plasma reactor with a CH4/H2 gas mixture. Nanocrystalline columnar-structured diamond film with lowering of sp2-bonded carbon content was achieved by the two-step deposition process. Unlike that of the single-step process with 1%CH4, the two-step process promoted the morphology to more uniform and smoother film. The two-step process increased the higher grain boundary as well as decreased the sp2-bonded carbon content in the film, as compared with the single-step process with 2%CH4Subscript text.

scholarly journals Simulation-Based Development of a New Cylindrical-Cavity Microwave-Plasma Reactor for Diamond-Film Synthesis

Crystals ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 320 ◽  
Author(s):  
Qijun Wang ◽  
Gai Wu ◽  
Sheng Liu ◽  
Zhiyin Gan ◽  
Bo Yang ◽  
...  
Keyword(s):  
Cylindrical Cavity ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Optical Microscope ◽  
Plasma Chemical Vapor Deposition ◽  
Atomic Force ◽  
Single Crystal Diamond ◽  
Film Synthesis

A 2.45 GHz microwave-plasma chemical-vapor deposition (MPCVD) reactor was designed and built in-house by collaborating with Guangdong TrueOne Semiconductor Technology Co., Ltd. A cylindrical cavity was designed as the deposition chamber and a circumferential coaxial-mode transformer located at the top of the cavity was adopted as the antenna. Two quartz-ring windows that were placed far away from the plasma and cooled by water-cooling cavity walls were used to affix the antenna to the cavity and act as a vacuum seal for the reactor, respectively. This design improved the sealing and protected the quartz windows. In addition, a numerical simulation was proposed to predict the electric-field and plasma-density distributions in the cavity. Based on the simulation results, a microwave-plasma reactor with TM021 mode was built. The leak rate of this new reactor was tested to be as low as 1 × 10−8 Pa·m3·s−1, and the maximal microwave power was as high as 10 kW. Then, single-crystal diamond films were grown with the morphology and crystalline quality characterized by an optical microscope, atomic force microscope (AFM), Raman spectrometer, photoluminescence (PL) spectrometer, and high-resolution X-ray diffractometer. It was shown that the newly developed MPCVD reactor can produce diamond films with high quality and purity.

Highly Oriented Diamond Films Grown at High Growth Rate

2006 ◽  
Vol 956 ◽  
Author(s):  
Xianglin Li ◽  
Ramon Collazo ◽  
Zlatko Sitar
Keyword(s):  
Growth Rate ◽  
Methane Concentration ◽  
Microwave Plasma ◽  
Chemical Vapor ◽  
High Growth ◽  
Fold Increase ◽  
Nitrogen Addition ◽  
High Growth Rate ◽  
Process Window ◽  
Plasma Chemical Vapor Deposition

ABSTRACTHighly oriented diamond (HOD) films were grown at a high growth rate on (100) silicon substrates by microwave plasma chemical vapor deposition (MPCVD), following the standard bias-enhanced nucleation (BEN) process. The growth rate and diamond quality were investigated as a function of methane concentration in hydrogen (2-6%), and N2/CH4 ratio (0 to 0.12). A four-fold increase in the growth rate of HOD films and a three times faster expansion and coalescence of (100) facets was observed within the above process window. The films with the best quality were grown under an N2/CH4 ratio of 0.08 at methane concentration of 3.5%. The ratio of x-ray intensity between the first order twins and {111} poles was only 1%. A detailed study of the crystalline quality and phase purity as a function of methane concentration and nitrogen addition is presented.

Modelling of low-temperature/large-area distributed antenna array microwave-plasma reactor used for nanocrystalline diamond deposition

2018 ◽  
Vol 81 (1) ◽  
pp. 10804 ◽  
Author(s):  
Fabien Bénédic ◽  
Benoit Baudrillart ◽  
Jocelyn Achard
Keyword(s):  
Low Temperature ◽  
Antenna Array ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Radial Profile ◽  
Chemical Vapor ◽  
Gas Temperature ◽  
Large Area ◽  
Microwave Source ◽  
Distributed Antenna

In this paper we investigate a distributed antenna array Plasma Enhanced Chemical Vapor Deposition system, composed of 16 microwave plasma sources arranged in a 2D matrix, which enables the growth of 4-in. diamond films at low pressure and low substrate temperature by using H2/CH4/CO2 gas chemistry. A self-consistent two-dimensional plasma model developed for hydrogen discharges is used to study the discharge behavior. Especially, the gas temperature is estimated close to 350 K at a position corresponding to the substrate location during the growth, which is suitable for low temperature deposition. Multi-source discharge modeling evidences that the uniformity of the plasma sheet formed by the individual plasmas ignited around each elementary microwave source strongly depends on the distance to the antennas. The radial profile of the film thickness homogeneity may be thus linked to the local variations of species density.

Growth-rate dependence of the thermal conductivity of chemical-vapor-deposited diamond

1999 ◽  
Vol 14 (9) ◽  
pp. 3720-3724 ◽  
Author(s):  
Naira M. Balzaretti ◽  
Albert Feldman ◽  
Edgar S. Etz ◽  
Roy Gat
Keyword(s):  
Thermal Conductivity ◽  
Growth Rate ◽  
Thermal Diffusivity ◽  
Microwave Plasma ◽  
Plasma Reactor ◽  
Diamond Films ◽  
Chemical Vapor ◽  
Diamond Growth ◽  
Diffusivity Measurements ◽  
Chemical Vapor Deposited

The in-plane thermal diffusivity of chemical-vapor-deposited diamond films was measured as a function of diamond-growth rate. The films, 0.1–0.4 mm thick, were prepared in microwave-plasma reactor at growth rates ranging from 1 to 10 μm/h. A modification of Ångstöm's method was used to perform the diffusivity measurements. The thermal conductivity calculated from the thermal diffusivity shows an inverse relationship with growth rate. Analyses of Raman spectra indicate that both the line shifts and the line widths of the diamond Raman peak are practically independent of the deposition rate, except for the specimen grown at the highest growth rate.

Sign in / Sign up

Export Citation Format

Share Document