Temperatures and Hydrogen Atom Concentrations in a Microwave Plasma Used for Diamond Deposition

A spectroscopic analysis of the plasma is presented. The variations of H-atom temperatures and of H-atom mole fraction as a function of the methane percentage introduced in the feed gas and of the power density are shown. A comparison between excited H-atom and ground state H-atom temperatures measured respectively by Two Photon Allowed Transition (TALIF) and Optical Emission Spectroscopy (OES) is made. A study on the validity of the actinometry method (OES) for the H atoms is carried out based on theory and TALIF measurements. Excited H-atom temperature and ratios of emission intensities ( I H / I Ar ) are shown to constitute interesting spectroscopic parameters for measuring gas temperature and ground state H-atom mole fraction by OES.