Construction of a new C-H-O ternary diagram for diamond deposition from the vapor phase

A new C-H-O ternary diagram is presented based on radical species composition showing the regions for diamond deposition, non-diamond deposition, and no deposition from the vapor phase. This construction is based on the steady-state computations of gas-phase and gas-surface chemistry from the data points presented in the C-H-O ternary diagram based on feed gas composition by Bachmann ct al. (P.K. Bachmann, D. Leers, H. Lydtin. Diamond Relat. Mater. 1 (1991) 1). The analysis of the computational results indicates that the radical species composition does distinguish the three regions and helps explain the contradicting experimental data points using non-typical gas mixtures. The analysis also shows that the revised diagram based on radical species composition works only when carbon monoxide (CO) is treated as a non-participating species. The effects of temperature, pressure and flow rates on this new ternary diagram are also detailed. (C) 2000 Elsevier Science S.A. All rights reserved.