INVESTIGATION OF GAS-PHASE MECHANISMS DURING DEPOSITION OF DIAMOND FILMS

The deposition of diamond films is investigated by optical emission spectroscopy measurements. Using the microwave chemical vapour deposition technique, the system C:H:O is surveyed starting from hydrogen-rich oxygen-free mixtures by gradually adding oxygen and reducing the hydrogen content until finally reaching C:H:O = 1:4:1, i.e. CH4 + O-1/2(2). CH and C2 are shown to give good measures for different active carbon species, CH being correlated with the growth rate while C2 correlates inversely to the film quality. The main role of O2 is the transformation of active carbon into the more stable carbon monoxide.