Thermodynamics of diamond film deposition at low pressure from chlorinatedprecursors

The thermodynamics of diamond film deposition at low pressure from a C-H-Cl system have been made according to a non-equilibrium thermodynamic couplin g model proposed by J.-T. Wang in previous papers. A projective ternary C-H -Cl phase diagram and a temperature-gas composition phase diagram for carbo n deposition from the C-H-Cl system are obtained. Diamond growth regions, w hich represent the constraints of temperature and gas composition suitable for diamond growth, are predicted in our phase diagrams. Diamond growth reg ions accord with many experimental data reported in references. Thermodynam ic analyses show that the substrate temperature range suitable for diamond film deposition moves towards the low-temperature region with increasing Cl addition, and becomes narrower. Our analyses also indicate that Cl additio n enhances growth rate through two effects: increasing CH3 and C2H2 concent rations at growth surface and accelerating abstraction of surface-terminati ng atoms. The effects of Cl addition on diamond film quality are also discu ssed.