Analytical electron microscopy and Raman spectroscopy studies of carbon nitride thin films

Abstract

Deposition of carbon nitride thin films on Si(100) and polycrystalline Zr substrates was performed by dc magnetron sputtering of a graphite target under a pure nitrogen ambient. The resulting carbon nitride films (CN_x) are primarily amorphous with a small volume fraction of nanocrystallites. Both energy‐dispersive x‐ray analysis and electron energy loss spectroscopy measurements showed that the amorphous matrix has uniform nitrogen‐to‐carbon ratios ∼0.4–0.8 depending on deposition conditions. Carbon and nitrogen K edge structures obtained from electron energy loss spectroscopy studies suggest that the amorphous carbon nitride matrix is primarily sp² bonded. Apart from the carbon–nitrogen stretching vibration, Raman spectra of CN_x films closely resemble those of diamondlike carbon films. Intensity and peak width changes of Raman features in the 1300–1600 cm⁻¹ range due to inorganic carbon (D and G peak) under different deposition conditions are explained in terms of the extent of structural disorder in these films.