Spectroscopic determination of C{sub 2} in Ar/H{sub 2}/CH{sub 4} and Ar/H{sub 2}/C{sub 60} microwave plasmas for nanocrystalline diamond synthesis.

We have measured the steady state concentration of gas phase C{sub 2} in Ar/H{sub 2}/CH{sub 4} and Ar/H{sub 2}/C{sub 60} microwave plasmas used for the deposition of nanocrystalline diamond films. High sensitivity white light absorption spectroscopy is used to monitor the C{sub 2} density using the d{sup 3}II {l_arrow} A{sup 3}II (0,0) vibrational band of C{sub 2} as chamber pressure, microwave power, substrate temperature and feed gas mixtures are varied in both chemistries. Understanding how these parameters influence the C{sub 2} density in the plasma volume provides insight into discharge mechanisms relevant to the deposition of nanocrystalline diamond.