OPTICAL-PROPERTIES OF NITROGEN-RICH CARBON-FILMS DEPOSITED BY DC MAGNETRON SPUTTERING

Nitrogen-rich carbon films were grown by d.c. magnetron sputtering fro m a graphite target in various nitrogen/argon gas mixtures using two d ifferent substrate temperatures. Infrared spectroscopical investigatio ns were carried out in order to determine differences in the him compo sition and structure caused by the variation of the deposition conditi ons. The spectra are interpreted in terms of two bands which are typic ally found in the Raman spectra of CNx films. While the band at 1280 c m(-1) only slightly increases in absorption intensity with increasing nitrogen incorporation, the band at 1520 cm(-1) becomes much more pron ounced. Both bands shift to higher wavenumbers with increasing nitroge n content. Additionally, the films show a decrease in the absorption a bove 2500 cm(-1). The existence of different functional groups absorbi ng at 2130 cm(-1) can be suppressed by substrate heating up to 400 deg rees C during preparation, C=N groups absorbing above 2200 cm(-1), how ever, remain in the samples. In order to support the IR results additi onal ellipsometric measurements, investigations of him density and sto ichiometry were performed. Heating the substrates during deposition le ads to a reduced nitrogen incorporation.