Application of optical emission spectroscopy for the determination of optimal CVD diamond growth parameters in abnormal glow discharge plasma

Optical emission spectroscopy (OES) has been used to investigate the generation of active species in H-2/CH4 and H-2/Ar/CH4 AC abnormal glow discharge plasmas during chemical vapor deposition of polycrystalline diamond. The vertical, spatially resolved measurements illustrate that the concentration of atomic hydrogen decreases rapidly with distance from the center of the plasma column. The addition of argon to the gas mixture leads to a drop in the electronic temperature and an increase in gas temperature but causes decreased atomic hydrogen concentration and diamond film growth rate due to the reduction in molecular hydrogen concentration. The emissions were monitored as functions of such process parameters as discharge current, gas flow rate, operating pressure and argon content. Obtained relations identified by OES were found to be in good agreement with experimental diamond growth measurements. (C) 2013 Elsevier Ltd. All rights reserved.