Vapor growth parameters

Tanemura M, Iwata K, Takahashi K, Fujimoto Y, Okuyama F, Sugie H, et al. Growth of aligned carbon nanotubes by plasma-enhanced chemical vapor deposition optimization of growth parameters. J Appl Phys 2001 90 1529-33. 

Figure 46 Chemical vapor deposition parameters for growth of cBN. (Data from Refs. 278, 280, 281, 291, 293.)...

The effect of gravity on the liquid and vapor parameters in the inlet and outlet cross-section is presented in Figs. 8.12 and 8.13. It is seen that an increase in the gravity is accompanied by a significant growth of the liquid pressure (Fig. 8.12a). At the same time an increase of the vapor pressure in the outlet cross-section is observed. However, the rate of liquid and vapor pressure growth are very different. This causes an increase of the difference AP = gravity... 

It is shown that an increase in the heat flux is accompanied by an increase in the liquid and vapor velocities, the meniscus displacement towards the outlet cross-section, as well as growth of vapor to liquid forces ratio and heat losses. When is large enough, the difference between the intensity of heat transfer and heat losses are limited by some final value, which determines the maximum rate of vaporization. Accordingly, when is large all characteristic parameters are practically invariable. 

Chemical vapor deposition (CVD) of carbon from propane is the main reaction in the fabrication of the C/C composites [1,2] and the C-SiC functionally graded material [3,4,5]. The carbon deposition rate from propane is high compared with those from other aliphatic hydrocarbons [4]. Propane is rapidly decomposed in the gas phase and various hydrocarbons are formed independently of the film growth in the CVD reactor. The propane concentration distribution is determined by the gas-phase kinetics. The gas-phase reaction model, in addition to the film growth reaction model, is required for the numerical simulation of the CVD reactor for designing and controlling purposes. Therefore, a compact gas-phase reaction model is preferred. The authors proposed the procedure to reduce an elementary reaction model consisting of hundreds of reactions to a compact model objectively [6]. In this study, the procedure is applied to propane pyrolysis for carbon CVD and a compact gas-phase reaction model is built by the proposed procedure and the kinetic parameters are determined from the experimental results. 

Besides the already mentioned techniques, a low-temperature plasma has been adopted to enhance the reaction in CVC. Through the synthesis of AIN UFPs by an RF-plasma-enhanced CVC using trimethylaluminum [A1(CH3)3] and NH3 as reactants, the effect of experimental parameters on the rate of powder formation, particle size, and structure was examined (60). A high RF current was primarily connected to a high electron density, which activated the gas-phase reaction to promote the powder formation rate. The increase of both susceptor temperature and A1(CH3)3 concentration also increased the powder formation rate and enhanced the grain growth, where both mechanisms—coalescence by particle collision and vapor deposition on to particle surfaces—were believed to occur. 

The high vapor pressure of Zn allows even metallic mode operation without reactive gas baffling since desorption of surplus Zn can be achieved by sufficient substrate heating. The feasibility of this approach has been shown using high-rate reactive MF sputtering for ZnO Al films with a resistivity of 300 pXl cm at a growth rate of 9 nms-1. The process parameters are summarized in Table 5.2 [51]. 

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