Systematic study of diamond film deposition in an atmospheric-pressure stagnation-flow flame reactor

An experimental study of diamond-film deposition is reported that utilized a scaled-up, stagnation-flow flame reactor. Films were deposited using highly strained premixed acetylene-oxygen-hydrogen flames. The roles of flame stoichiometry, deposition temperature, and the use of nitrogen and argon diluents are evaluated. The experimental growth results are analyzed based on the participation of methyl and hydrogen radicals in the diamond growth process. The deposition results, both growth rates and film quality based on Raman and SEM analysis, correlated well with recent calculations of the predicted methyl radical to atomic hydrogen ratios. Flame temperature was found to have a pronounced effect on diamond deposition that is likely coupled to the delivery of methyl radicals and hydrogen atoms to the substrate surface. Overall, the atmospheric-pressure reactor performed well, demonstrating successful scale-up, but flame stability and other engineering controls were necessary for achieving uniform diamond deposition and high growth rates.