Filament-assisted diamond growth kinetics

We have measured the growth rate of chemical vapor deposition diamond films under filament-assisted conditions using a microbalance. The pressure was varied from 20 to 200 Torr, and the ratio R of CH4 to H2 was varied from 0.2% to 1%. Raman spectra showed only diamond features for our films. We found that for R≳0.2%, where filament carburization was not an issue, the growth rate scaled as Rα, where α is an empirical constant that varies from about 1 at 20 Torr to about 0.5 at 200 Torr. A comparison of these results to predictions of our gas-phase/gas-surface model for diamond growth shows that the model accurately predicts both the value of α and how α varies with pressure. Reasons for the success of our very simple model are discussed.