The deposition of diamond films via the oxyacetylene torch: Experimental results and thermodynamic predictions

Abstract

The deposition of diamond films has been carried out via the oxyacetylene torch onto Mo and Si substrates. The phase diagram for deposition of diamond in the substrate temperature T s versus reactant ratio O / C plane has been experimentally determined. The growth of diamond has been observed for 650 ≤ T s ≤1320°C and 0.89 ≤ O 2 / C 2H 2 ≤ 0.99. The thermodynamic quasi-equilibrium model for the CVD of diamond has been extended to the C-H-O system and applied to O 2/C 2H 2 mixtures. Predictions for the rates of formation of gaseous species and of solid carbon have been obtained as functions of T s, the O/C ratio, and pressure. The CVD phase diagram for the oxyacetylene torch has been predicted and compared with our own experimental results and those of other workers. The distributions of film morphologies on the substrate surfaces are described and explained in terms of the changing O / C ratio in the flame and the variation of the substrate temperature within the growth region.