Boron nitride (BN), carbon nitride (CN), and boron carbon nitride (BCN) thin films were deposited on sapphire and silicon using ion beam and electron cyclotron resonance plasma assisted physical vapor deposition. In situ Auger electron spectroscopy was used to investigate the effect of different growth parameters and postgrowth processing on the thin film surface composition. The bulk composition was determined by electron energy loss spectroscopy and electron microprobe analysis. Both BN and CN films show thermal stability up to 900 and 700 degrees C, respectively. Low growth temperatures favor nitrogen incorporation in CN films and the optimum temperature for quasistoichiometric BN is between 450 and 600 degrees C, depending on the nitrogen sources.