Influence of N_2 Addition for Diamond Films Synthesized by Combustion Flame Method Using High Purity Acetylene Gas

Diamond films have been synthesized by combustion flame using commercial acetylene-oxygen mixture gas. But, the combustion flame condition was unstable by emitting of the acetylene gas during the synthesis of diamond films. This cause was that purity of commercial acetylene gas was not stable by included impurities in dissolution acetylene. In this study, high purity acetylene gas was used, because the purity of the pure acetylene gas was stable by using high purity special dissolution acetylene. But, diamond films were not synthesized on a Mo substrate by combustion flame using high purity acetylene gas. Therefore, nitrogen gas as diamond promotion ingredient was added to high purity acetylene-oxygen mixture gas to synthesize diamond films. And, to investigate of the synthesis of the diamond film, nitrogen flow rate was changed. Here, to prevent the film delamination, a three-step synthesis method was used. The results show that the synthesized film in the case of the nitrogen flow rate 0.500cm^3/s was a good diamond film.