Production of boron nitride using chemical vapor deposition method

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2014
Mercan, Özge
Boron nitride is a promising material with its outstanding characteristics like chemical inertness, large band gap, high oxidation resistance and thermal conductivity. It is also used as ceramic matrix component which transfers external load and deflects matrix cracks. Therefore, it has become a subject matter for many studies. In this study, the process of boron nitride (BN) production from diborane (B2H6) and ammonia (NH3) on tungsten (W) substrate in impinging jet reactor is investigated using chemical vapor deposition (CVD) method. The process parameters; temperature of the substrate, total gas flow rate and concentration ratio of the precursors are studied to obtain the highest deposition rate in the impinging jet reactor. The composition, structure and morphology of the produced films were studied using XRD, XPS, Raman Spectroscopy and SEM methods. XRD analyses of the products showed that boron nitride formed on the tungsten substrate. Atomic ratio of the elements in the produced film was obtained from XPS analysis which shows that other boron products might be formed in the product as well. Raman Spectroscopy gave information about the existence of the B-N bonds. SEM analyses showed that the morphology of the produced films changes with respect to temperature. Effect of temperature on deposition rate was studied between 900oC and 1200oC. It is found that deposition rate is positively correlated with temperature. Different molar ratios of B2H6 to NH3 were studied in order to analyze the effects of different molar ratios on the deposition rate and morphology of the film. It is found that, at the molar ratio of 0.033 and 0.099, the morphology of the film is similar. At the molar ratio of 0.050, rounded grains on the topography were observed. Deposition rate of the film reaches to maximum when the reactants are fed to the reactor at the molar ratio of 0.050. The effects of total flow rate on the deposited film were investigated keeping the concentration of the reactants constant. Total flow rate is negatively correlated with deposition rate due to the residence time of the reactants in the reactor. Thickness analyses were done to observe the profıle throughout the fılm. As a result, it is found that the highest deposition rate is obtained at the temperature of 1200oC with a total flow rate of 150 ml/min and molar ratio ([B2H6]/[NH3]) of 0.050.

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Citation Formats
Ö. Mercan, “Production of boron nitride using chemical vapor deposition method,” M.S. - Master of Science, Middle East Technical University, 2014.