Kinetic regularities of the chemical vapor deposition of nickel layers from bis-(ethylcyclopentadienyl)nickel

Physicochemical regularities of the nickel layers chemical vapor deposition from bis-(ethylcyclopentadienyl)nickel were studied. Dependences of the growth rate of nickel layers on the deposition temperature, gas-flow linear rate, partial pressures of reagents, and substrate roughness, and also dependences of the thickness of a grown layer on time and on the position of a substrate on a susceptor were obtained.     

Magnetic property and structural study of nickel supported on reduced graphene oxide prepared by chemical vapor deposition

Nickel supported on reduced graphene oxide was synthesized by chemical vapor deposition technique. The crystal structure and magnetic properties of the prepared sample were studied by means of Raman spectrometry, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), inductively coupled plasma optical emission spectrometry (ICP-OES), and vibrating sample magnetometry (VSM). The result of Raman spectroscopy revealed the structure of few-layer graphene as the support for Ni nanoparticles. XP spectrum confirmed the presence of metallic Ni on the a few-layer graphene surface. TE micrograph showed that the nickel nanoparticles were sphere shaped and the mean particle size is about 20 nm deposited on the reduced graphene oxide. The magnetic study showed the ferromagnetic behavior of 3.2 wt% nickel over reduced graphene oxide at room temperature.     

Solid oxide fuel cells with film electrolytes prepared by chemical vapor deposition

Basing on the developed film formation technique by organometallic chemical vapor deposition (organometallic CVD), thin films of electrolytes were prepared on supporting anode and experiments were carried out to optimize the cathodic layer forming conditions. The individual electrochemical cell achieved the specific power of 1190, 800, and 350 mW/cm² at the temperatures of 800, 700, and 600°C, respectively. Operation of a 13 cm² fuel cell in solid oxide fuel cell (SOFC) battery was studied.     

Plasma chemical vapor deposition of TiN

Experiments indicate that the temperature in chemical vapor deposition (CVD) of TiN can be decreased from about 1000°C in conventional CVD to about 500°C by the application of a D.C. nonequilibrium plasma. The hardness of the TiN film is greater than 2000 kg/mm² (Vickers). The effect of pressure, ratio of gas mixture, and discharge parameters on the film deposition rate, its hardness, and microstructures has been studied.     

Salt-assisted chemical vapor deposition of two-dimensional materials

Two-dimensional(2D) materials with atomic thickness are promising candidates for the applications in future semiconductor devices, owing to their fascinating physical properties and superlative optoelectronic performance. Chemical vapor deposition(CVD) is considered to be an efficient method for large-scale preparation of 2D materials toward practical applications.However, the high melting points of metal precursors and the thermodynamics instabilities of metastable phases limit the direct CVD synthesis of plenty of 2D materials. The salt has recently been introduced into the CVD process, which proved to be effective to address these issues. In this review, we highlighted the latest progress in the salt-assisted CVD growth of 2D materials, including layered and non-layered crystals. Firstly, strategies of adding salts are summarized. Then, the salt-assisted growth of various layered materials is presented, emphasizing on the transition metal chalcogenides of stable and metastable phases. Furthermore, strategies to grow ultrathin non-layered materials are discussed. We provide viewpoints into the techniques of using salt, the effects of salt, and the growth mechanisms of 2D crystals. Finally, we offer the challenges to be overcome and further research directions of this emerging salt-assisted CVD technique.     

High oxygen vacancy tin oxide synthesized by combustion chemical vapor deposition (CCVD)

Tin oxide nanotentacles were synthesized by combustion chemical vapor deposition in air. Their surface composition and optical properties were then investigated using X‐ray photoelectron spectroscopy (XPS) and Raman spectroscopy. XPS core level spectra indicate that these nanotentacles are of high oxygen vacancy with chemical composition of about SnO_1.6, which is also supported by the Sn Auger parameter. Besides SnO₂, the optical properties of SnO were detected in Raman spectrum. Moreover, two new Raman peaks were found for the SnO₂ phase because of the high oxygen vacancy concentration. Copyright © 2008 John Wiley & Sons, Ltd.     

Organometallic chemical vapor deposition using allyl precursors

Homoleptic allyl derivatives of many Main-Group and transition metals, M(C₃H₅)_n, are readily available through one-pot syntheses using metal halides and allyl Grignard reagents or by alkylation of alkali-metal salts. The relatively low molecular weight of a C₃H₅ ligand contributes to high vapor pressures whilst the stability of the allyl radical is predicted to reduce decomposition temperatures. These compounds represent a class of volatile precursors for organometallic chemical vapor deposition (OMCVD) of thin films. Film growth studies using iridium, molybdenum, palladium, platinum, rhodium, selenium, tellurium and tungsten compounds are reviewed and the relationships between pyrolysis pathways and film purity are discussed.     

硅纳米线的化学气相沉积法合成

硅纳米线是近十几年来在纳米科学与技术领域快速发展的一种重要材料．通过精细的结构设计与材料合成,硅纳米线在生物传感、锂离子电池、太阳能电池和光电化学等领域展示出良好的应用前景．化学气相沉积（CVD）法是一大类重要的自下而上合成硅纳米线方法．本文简介了CVD法合成硅纳米线的主要进展,包括具有单一结构和复合结构的硅纳米线的合成．其中,单一结构的硅纳米包括本征（无掺杂）、掺杂和超长的硅纳米线;复合结构的硅纳米线包括轴向异质结、径向异质结、转折结构和树枝状结构的硅纳米线．     

Functionalization of parylene during its chemical vapor deposition

Two possible mechanisms for the reaction of four halogenated (metha)acrylate‐based molecules with Parylene [poly (paraxylylene)] during its chemical vapor deposition were proposed. The chemical reactivity of acrylate double bond with the paraxylylene biradical was calculated for all four (metha)acrylate‐based molecules. These calculations allowed the evaluation of the energetically favorable mechanism and indeed a direct correlation was found between both predicted and experimental reactivities. Next, the reactivity of the (metha)acrylate‐modified Parylene films was evaluated through their reaction with different amines. The obtained amidated Parylene films were characterized with X‐ray photoelectron spectroscopy, Kaiser test for primary amines, and fluorescence microscopy. The strong reactivity of (metha)acrylate‐modified Parylene films toward nucleophilic substitution emphasizes a general method for the functionalization of self‐supported Parylene films grown on the reacting solutions using the novel solid on liquid deposition process. This paves the way to the development of multifunctional materials in a one‐step process resulting from the deposition Parylene over liquid patterns. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Ti-Si-N films prepared by plasma-enhanced chemical vapor deposition

Ti-Si-N thin films were deposited on HSS substrates at 560°C using plasmaenhanced chemical vapor deposition. Feed gases used were TiCl₄, SiCl₄, N₂, and H₂. The composition of the films could be controlled well through adjustment of the mixing ratio of the chlorides in the feed gases. The Si content in the film varied in the range of O to 40 at. %. It was jbund that a small addition of Si to a TiN film improved the morphology significantlv, showing dense and glasslike structure. Also a much smootherand more homogeneous interface between thefilm and the substrate was obtained. The Ti-Si- N films containing 10–15 at. % Si showed the maximal microhardness value of about 6350 kgf/mm², much higher than that of TiN films.     

Two-dimensional model for thermal plasma chemical vapor deposition

A formulation of a global mathematical two-dimensional model for Thermal Plasma Chemical Vapor Deposition (TPCVD) is reported. Both gas-phase and surface chemical kinetics as well as ordinary and thermal diffusion are incorporated. Flow is assumed to be steady, laminar and swirlless at this stage. The results include velocity, pressure, density, temperature and chemical species distributions in the reactor, and the heat flux and the film growth characteristics at the substrate.The model has been applied to a low pressure diamond TPCVD. Two basic cases have been investigated: (1) supersonic jet regime, and (2) high speed subsonic jet regime. The results for both cases are presented and compared. In both cases, the hydrocarbon species needed for the diamond formation are assumed to be premixed in the plasma jet.The main conclusions are: (1) The low pressure high speed jets are very narrow and slow down only at the substrate through a bow shock, (2) the faster the jet, the bigger the total deposited amount of diamond but also the higher the heat flux and diamond growth rate nonuniformities.     

Structure,composition, and electrical resistance of thin ruthenium metallic layers obtained by pulsed chemical vapor deposition

We systemize the experimental data on the relationship of the specific electrical resistance, density, structure, and composition of thin ruthenium layers (TRLs) synthesized in the temperature range 160-310 °C by pulsed chemical vapor deposition with a carbonyl-diene precursor Ru(CO)₃(C₆H₈) and NH₃ and N₂O as second reagents. The main impurity in TRLs after their deposition and annealing is carbon with a concentration of ~30-50 at.%. To increase the density and decrease the electrical resistance of TRLs to values below 50 μOhm?cm it is reasonable to use N₂O in the synthesis and also to apply the subsequent thermal annealing of TRLs at temperatures up to 700 °C, which improves the crystal structure of the layers.     

Model of carbon nanotube growth through chemical vapor deposition

This Letter outlines a model to account for the catalyzed growth of nanotubes by chemical vapor deposition. It proposes that their formation and growth is an extension of other known processes in which graphitic structures form over metal surfaces at moderate temperatures through the decomposition of organic precursors. Importantly, the model also states that the form of carbon produced depends on the physical dimensions of the catalyzed reactions. Experimental data are presented that correlate nanotube diameters to the size of the catalyst particles. Nanotube stability as a function of nanotube type, length and diameter are also investigated through theoretical calculations.     

Initiated chemical vapor deposition of trivinyltrimethylcyclotrisiloxane for biomaterial coatings

Organosilicon polymers show great utility as both biocompatible and electrically insulating materials. In this work, thin films of a novel organosilicon polymer are synthesized by initiated chemical vapor deposition utilizing trivinyltrimethylcyclotrisiloxane as a monomer and tert-butyl peroxide as a free-radical-generating initiator. Use of an initiator allows for the formation of polymer films at filament temperatures as low as 250 degrees C, significantly lower than those required to thermally polymerize the monomer species. The mild reaction conditions allow for the retention of all siloxane ring moieties within the resulting polymer. Films deposited at filament temperatures of 600 degrees C or higher exhibit damage to this moiety. The all-dry deposition process generates a highly cross-linked matrix material in which over 95% of the vinyl moieties present on the monomer units have been reacted out to form linear polymerized hydrocarbon chains. While each hydrocarbon backbone chain averages 8.9 monomer units in length, as evaluated by X-ray photoelectron spectroscopy analysis, each monomer unit is involved in three independent chains, resulting in polymer films of such high molecular weight that they are completely insoluble. Kinetic analysis of the deposition process indicates that the film formation rate is limited by the adsorption of reactive species to the deposition substrate, with an apparent activation energy of -23.2 kJ/mol with respect to the substrate temperature. These results are consistent with a surface growth mechanism, ideal for the coating of nonuniform or high aspect ratio substrates.     

Epitaxial polymerization of 1,3-butadiyne by chemical vapor deposition

1,3-Butadiyne was epitaxially polymerized on the graphite basal plane by chemical vapor deposition to form a homogeneous thin film. The film thickness varied from 100 to 3000 Å depending on the polymerization condition. The films on the graphite showed a variety of interference colors such as blue, purple, or gold depending on the film thickness. Raman spectra revealed that the polymerized film was mainly composed of ? C?C? bonds. Electron diffraction pattern and the ESCA spectrum of the film were quite similar to those of graphite, suggesting that butadiyne was polymerized in an epitaxial manner.     

Magic carbon clusters in the chemical vapor deposition growth of graphene

Ground-state structures of supported C clusters, C(N) (N = 16, ..., 26), on four selected transition metal surfaces [Rh(111), Ru(0001), Ni(111), and Cu(111)] are systematically explored by ab initio calculations. It is found that the core-shell structured C(21), which is a fraction of C(60) possessing three isolated pentagons and C(3v) symmetry, is a very stable magic cluster on all these metal surfaces. Comparison with experimental scanning tunneling microscopy images, dI/dV curves, and cluster heights proves that C(21) is the experimentally observed dominating C precursor in graphene chemical vapor deposition (CVD) growth. The exceptional stability of the C(21) cluster is attributed to its high symmetry, core-shell geometry, and strong binding between edge C atoms and the metal surfaces. Besides, the high barrier of two C(21) clusters' dimerization explains its temperature-dependent behavior in graphene CVD growth.     

New molecular compound precursor for aluminum chemical vapor deposition

A new type of precursor for aluminum chemical vapor deposition (Al‐CVD) has been developed by mixing dimethylaluminum hydride (DMAH) and trimethylaluminum (TMA). The new precursor has proven itself to be effective for Al‐CVD, where a good selectivity between the Si and the SiO₂ mask, a 3.0 μΩ cm resistivity and a pure Al film with low C and O contamination levels (under 100 ppm) were achieved. Quadrupole mass and infrared absorption analysis have shown that the precursor contains a new molecular compound, consisting of a DMAH monomer and a TMA monomer. The mixture has lower viscosity than DMAH and can be easily bubbled for a stable precursor vapor supply. Copyright © 2000 John Wiley & Sons, Ltd.