Chemical vapor deposition thermal laser

Different fabrication methods such as the thermal evaporation [4], MOCVD (metal organic chemical vapor deposition) [5], laser ablation and wet chemical synthesis [6,7] have been reported for the preparation of ZnO nanoparticles and films. 

Sol-gel Chemical vapor deposition (thermal, plasma, laser induced)... 

The synthesis of MNCGs can be obtained by sol-gel, sputtering, chemical vapor-deposition techniques. Ion implantation of metal or semiconductor ions into glass has been explored since the last decade as a useful technique to produce nanocomposite materials in which nanometer sized metal or semiconductor particles are embedded in dielectric matrices [1,2,4,23-29]. Furthermore, ion implantation has been used as the first step of combined methodologies that involve other treatments such as thermal annealing in controlled atmosphere, laser, or ion irradiation [30-32]. 

The preparation of CNTs is a prerequisite step for the further study and application of CNTs. Considerable efforts have been made to synthesize high quality CNTs since then-discovery in 1991. Numerous methods have been developed for the preparation of CNTs such as arc discharge, laser vaporization, pyrolysis, and plasma-enhanced or thermal chemical vapor deposition (CVD). Among these methods, arc discharge, laser vaporization, and chemical vapor deposition are the main techniques used to produce CNTs. 

Fabrication methods include thermal evaporation, sputtering, magnetron sputtering, pulsed laser evaporation, molecular beam epitaxy, chemical vapor deposition, electrolytic and electroless deposition, and growth from solution. 

Higher germanes have also been studied for the purpose of investigating routes for chemical vapor deposition (CVD) of germanium. For example, the results obtained from the sensitized thermal decomposition of Me4Ge promoted by multiphoton vibrational excitation of SF5 using a pulsed CO2 laser are consistent with the pyrolytic decomposition " that points out to a Ge—C bond cleavage as the primary process (equation 36). 

Chemical vapor deposition (CVD) is an atomistic surface modification process where a thin solid coating is deposited on an underlying heated substrate via a chemical reaction from the vapor or gas phase. The occurrence of this chemical reaction is an essential characteristic of the CVD method. The chemical reaction is generally activated thermally by resistance heat, RF, plasma and laser. Furthermore, the effects of the process variables such as temperature, pressure, flow rates, and input concentrations on these reactions must be understood. With proper selection of process parameters, the coating structure/properties such as hardness, toughness, elastic modulus, adhesion, thermal shock resistance and corrosion, wear and oxidation resistance can be controlled or tailored for a variety of applications. The optimum experimental parameters and the level to which... 

Nowadays, many advanced techniques are available in the ceramic industry to coat a solid layer onto a solid surface or to make ceramic materials with special properties [99-1 IS], such as spin-coating [99], chemical vapor deposition [100-106], and chemical vapor infiltration [106-109], thermal spray [110-112], plastic spray [113], and spray-coating [114]. The deposition can be caused by conventional heating, by laser beam, or by microwave heating. 

These specialized forms of CVD, referred to as nontraditional techniques for the purpose of this review, include laser (LCVD), aerosol (ACVD), hot filament (HFCVD), and ion beam (IBGVD) chemical vapor deposition. In such enhanced CVD technologies, a thermal CVD reaction occurs simultaneously with another driving force, which results... 

The OAG method has a general nature and can be applied to a variety of materials other than Si. Based on the OAG method, we have synthesized nanowires of a wide range of semiconducting materials including Ge [35], GaN [36, 37], GaAs [38, 39], GaP [41], SiG [40], and ZnO (whiskers) [42]. The actual OAG process was activated by laser ablation, hot-filament chemical vapor deposition (HFCVD) or thermal evaporation. 

At a microscopic level the contact surface is restricted by peaks and valleys and even highly polished surfaces may exhibit a high peak to valley ratio. This makes it necessary to use an extremely flat contact surface between the heat source and thermal spreader to guarantee an efficient transfer of heat. Chemical vapor deposition diamond with a thickness of 1000 pm has been used for Multi Chip Modules (MCM) for this purpose. Heat spreaders are used in the electronic industry for IC packaging and solid-state lasers. 

The methods proposed in the literature to do so, e.g. spin-coating [9], thermal evaporation [10], chemical vapor deposition [11], flash evaporation [12], laser deposition [13] and r.f. reactive sputtering [14], are rather scarce and complex. Moreover, they are often more dedicated to the deposition of active phase on flat and/or monolithic supports (to produce model catalysts for surface science purposes) than on powder supports. These methods thus usually only allow the production of samples at a small scale, so that they are often inadequate for the production of pulverulent real catalysts in large amounts. 

High-speed coating process, such as plasma spray and electron physical vapor deposition (EB-PVD), has been used for thick coating typically thermal barrier coating (TBC), To improve the performance of TBC, a new coating route should be developed. This review briefly introduces conventional high-speed coating processes, and also describes a new laser chemical vapor deposition (LCVD) technique invented by the present authors. 

Numerous processing techniques are used to deposit and bond Ca-P powders to substrates, in-clusing plasma and thermal spraying (de Groot et al., 1987 Koch et al., 1990), ion-beam and other sputter-deposition techniques (Ong et al., 1S>91 Wolke et al., 1994), electrophoretic deposition (Ducheyne et al., 1986, 1990), sintering (de Groot, 1983 Ducheyne et al., 1986, 1990), sol-gel techniques (Chai et al., 1998), pulsed laser deposition (Garcia et al., 1998), and chemical vapor deposition (Gao et al., 1999). 

Laser assisted chemical vapor deposition (LCVD) is a relatively new process. It has already shown promise of becoming a major route for the fabrication of (1) potentially continuous small diameter fibers having premium structural, thermal or optical functionality, (2) complex fiber based microparts such as microsprings and solenoids, and (3) microdevices which operate by using coupled electrical, magnetic and thermal fields. Three excellent reviews should be consulted for details [1-3]. 

H, Westberg, Thermal laser assisted chemical vapor deposition, Acta Universitatis Upsaliensis, Comprehensive summary of dissertations, No. 375, Faculty of Science, University of Uppsala, Sweden (1992). 

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