Nucleation enhancement and growth of diamond films using an enclosed combustion flame
This research investigates the growth of diamond thin films using an enclosed oxyacetylene torch. Using statistical experimental design, we have systematically explored the parameter space to construct maps of nucleation density, film quality, and growth rate as functions of growth conditions. The deposition process is divided into nucleation enhancement and growth, and each step is optimized separately. In the study of the nucleation enhancement, we vary R = O2C2H2, substrate-flame distance (z), and pretreatment time and determine the nucleation density and nucleation uniformity using electron microscopy. For the growth study, the variables are R, z, and substrate temperature, and we employ two different Raman scattering measurements to assess film quality. In one case, we determine a quality ratio β = diamond peak/(diamond peak+nondiamond peak); the second indicator is the luminescence determined from the baseline of the spectrum. In the growth study, the best film quality is comparable to the best films grown in an atmospheric flame in which R is cycled. We also find that the growth rate is a factor of 10 less than in the atmospheric flame.
