Effects of methane concentration on growth stability of thick diamond film prepared by DC arc plasma jet

Diamond film wafers with different thickness were prepared by high power DC are plasma jet CVD method. The diamond film growth was unstable at some methane concentrations and the instability degree depends on the methane concentration. Theoretical analysis and experimental investigation show that the instability is mainly attributed to the high super saturation of carbon concentration due to the high temperature arc jet. Based on the experimental observations, it is suggested that in order to realize stable growth of high-quality thick diamond film, the methane concentrations should be controlled at a low level.