The morphology of the carbon nitride (C1-xNx) thin films deposited by the reactive ion beam sputter deposition technique has been studied. A pure graphite target has been sputtered using nitrogen ions. Some of the deposited films have been irradiated with the primary nitrogen ion beam during the deposition. The films were prepared at room temperature on the crystalline Si substrates. The IR absorption spectrum of the C1-xNx film irradiated with lower energy (0.6 keV) ions has an absorption band that peaked at 1550 cm(-1), which has been attributed to the graphitic sp(2)-bonded carbon (G band) in the study of Raman spectroscopy, while the nonirradiated film which was deposited with a 0.6 keV beam has shown neither a G band nor a D band corresponding to the disordered sp(3)-bonded carbon in the IR spectra. On the other hand, the films irradiated with a higher energy (1.0 keV) ion beam have shown a very broad "D-band" IR spectrum in the IR range between 1000 and 1700 cm(-1). The x-ray photoelectron spectroscopy spectra indicate that all films contain nearly equal quantities of the C=N triple and C=N conjugated double bonds, while the LR absorption peaks attributed to the C=N stretching mode are larger in the ion-irradiated samples than in the nonirradiated ones. These results suggest that sputtering by and/or irradiation of a higher energy ion beam contribute to form terminations of the diamondlike carbon network, which contains pyridinelike structures, in the form of cyano-radicals since the absorption peak due to the C=N stretching mode is enhanced when cyano-radicals bond with a conjugated system in the neighboring sites.