Surface reaction kinetics of gas-phase diamond growth

Surface reaction kinetics for diamond growth by chemical vapor deposition (CVD) was investigated experimentally. The temperature dependence for the growth rate exhibited surface-reaction controlled kinetics with the activation energy of about 23 kcal/mol below 900 °C. The dependence of the growth rate on the other CVD parameters and the corresponding calculated concentration of H and CH3 gave the growth rate (GR) expression GR= kX0HX1CH3, where k and Xi are a rate constant and the mole fraction of species i, respectively. A decrease in the activation energy for apparent diamond-film growth with increasing nondiamond carbon content was also discussed in relation to the role of gaseous H atoms. A dramatic decrease of the activation energy occurred at high pressure (300 Torr) deposition, since the growth kinetics changed to the diffusion controlled growth.