Carbon nitride films on silicon (111) and (100) wafers and Ti/C substrates with nitrogen concentration up to 50 at. % have been prepared by ion beam enhanced deposition carried out in a single ion source system. The possibility of synthesis of carbon nitride films was investigated. The nitrogen concentration and the compositions of the films were analyzed by Rutherford backscattering which gave out the nitrogen concentration of the films ranging from 37 to 50 at. %, Fourier transform infrared spectroscopy, and x‐ray photoelectron spectra. The characteristics of C 1s peaks at 284.6, 285.9, 287.5, 289.5, eV and N 1s peaks at 396.0, 398.4, 399.9, 402.1 eV enabled us to analyze the compositions of the films. The results of the analyses indicate that various phases such as different carbon phases, a tetrahedrally bonded phase (β‐C3N4) and other carbon nitrides (the ratio of N/C varied from 0.5 to 1.1) are contained in the films. Furthermore the concentration of the tetrahedrally bonded phase increases with the increment of the nitrogen concentration. © 1996 American Institute of Physics.