X-ray photoelectron spectroscopy study of carbon nitride coatings deposited by IR laser ablation in a remote nitrogen plasma atmosphere

The reactive pulsed laser deposition technique was used to deposit carbon n itride (CNx) coatings on a silicon substrate. In this process, an infrared transversely excited atmospheric pressure CO2 laser ablation of a graphite target in a remote nitrogen plasma afterglow was used to provide simultaneo usly both carbon- and nitrogen-containing species. Evidence of different CN bonding configurations has been observed in the deposited coatings. For ni trogen pressures (P-N2) of greater than or equal to 700 Pa there is an incr ease in the contribution of sp(2) carbon atoms that is associated with grap hitization of the CN, coatings. For P-N2 increasing from zero to 100 Pa, th e comparison between XPS core-level and valence band spectra of the CN, coa tings shows good correlation between the p-derived states (C 2p electrons) of C-C pi bonds in the valence band and the sp(2) carbon atom concentration deduced from the C 1s spectra. The progressive positive contribution of nitrogen lone pair electrons to th e valence band is consistent with the increase of the N-C sp(3) contributio n with P-N2. The decrease in the sp(2) carbon atom contribution is associat ed with the increase of the nitrogen concentration in the coatings. Copyrig ht (C) 2001 John Wiley & Sons, Ltd.