Abstract: According to the non-equilibrium thermodynamic coupling model, a phase diagram for diamond growth in C-H-Cl system was calculated. A diamond growth region which is in
good agreement with many reported experiments exists in the calculated phase diagram. Compared to the diamond growth region in the phase diagram of diamond growth in
C-H system, the diamond growth region presented here moves toward the end of low substrate temperature. The effect of chlorine addition on diamond growth
in the vapor phase was also discussed according to the reaction mechanism.

Key words: C-H-Cl system, diamond, phase diagram