The effect of CO2 on the high-rate homoepitaxial growth of CVD single crystal diamonds

In this paper, we report the effect of gaseous carbon dioxide (CO₂) introduced in the typical reaction atmosphere of CH₄/H₂/N₂ (60/500/1.8 in sccm) on the growth rate, morphology and optical properties of homoepitaxy single crystal diamonds (SCDs) by microwave plasma chemical vapor deposition. The additional carbonaceous sources supplied by CO₂ are favorable to increase the growth rate, and meanwhile, the oxygen related species generated would enhance the etching effect not only to eliminate the non-diamond phase of SCD but also to decrease the growth rate. The appropriate addition of CO₂ can increase the high growth rate, decrease the surface roughness, and reduce the concentration of N-incorporation. It is demonstrated that adding CO₂ strongly affects the contents of various reaction species in plasma, which would determine the growth features of CVD SCDs.