Measurement of C2 radical density in microwave methane/hydrogen plasma used for nanocrystalline diamond film formation

C-2 radical density in a conventional microwave plasma-enhanced chemical vapor deposition (MWPCVD) with CH4/H-2 mixture was measured using absorption spectroscopy. At the typical growth conditions for MWPCVD used for nanocrystalline diamond formation, C-2 radical density in the plasma was of the order of 10(12) cm(-3). Correlation between nanocrystalline diamond growth and C-2 radical density was discussed. (C) 2002 Elsevier Science B.V. All rights reserved.