A theoretical study of the chemical vapor deposition of (100) diamond: An explanation for the slow growth of the (100) surface

Abstract

In this investigation we use B3LYP density functional theory (DFT) to investigate the CVD growth mechanism of (100) diamond. Our results are consistent with the Garrison mechanism in which the dimer-opening step involves simultaneous formation of a surface olefin and dissociation of the dimer. We calculate this step to have a barrier of 9.6 kcal/mol. The olefin is then attacked by a surface radical to form a six-membered ring. We find this reaction to be the rate-limiting step with an activation energy of 13.6 kcal/mol. This is in excellent agreement with the experimental value of 15 kcal/mol obtained by the selective growth method and XPS. The direct ring-opening and ring-closing reaction from adsorbed CH2 radical has an activation energy of 49.4 kcal/mol and does not contribute significantly to the growth rate. The barrier on larger clusters that include the effects of neighboring adsorbed hydrogen increases to 15.6 kcal/mol. Additionally, our calculated vibrational frequencies agree within 2% of experimental IR and HREELS spectra. (C) 2000 American Institute of Physics. [S0021-9606(00)70541-1].