Experimental and computational investigation of the thermal effects on CVD diamond films by oxy-acetylene combustion method

Scope and method of study. This study was undertaken to make a step forward to the industrialization of the oxy-acetylene combustion method in diamond synthesis by developing guidelines for producing a good-quality diamond film. Systematic experiments of the substrate temperature measurements were conducted to study the influence of several parameters on the substrate temperature profile. Also, the dependencies of morphology and quality of the diamond film produced by the oxyacetylene combustion method were studied by analyzing the produced films using SEM (scanning electron microscope). To predict the substrate surface temperature distribution, a computer code was developed based on the heat transfer model developed in this study.; Findings and conclusions. The experimental techniques used in this study established the radial variation of the substrate surface temperature under a variety of operating conditions. The experimental results indicated clearly that the shape and the magnitude of the substrate surface temperature profile were influenced by several parameters. These parameters were the oxygen and acetylene flow rates, the substrate position in the combustion flame, the substrate-heat sink distance, the coolant flow rate, and the nozzle size. For a desired substrate surface temperature level and shape, it was found that a proper combination of these parameters should be used. The morphology and quality of a diamond film were shown to have a strong relation with the substrate temperature profile and the nozzle size. The cubo-octahederal structure was produced at substrate surface temperatures above 900{dollar}spcirc{dollar}C while the octahederal structure was dominant at temperatures below 900{dollar}spcirc{dollar}C. Diamond films consisting of large grains resulted from small nozzle size and high substrate surface temperature. The predicted substrate surface temperature profiles from the computer simulations were in good agreement with the experimental results. The developed computer code was shown to be an efficient tool to predict the resulting morphology and quality of a diamond film under certain operating conditions.