The composition, growth mechanism, and phases of carbon nitride thin films obtained from the reaction of laser ablated carbon and atomic nitrogen have been investigated. The nitrogen composition was found to increase to a limiting value of 50% as the fluence was decreased for laser ablation at both 532 nm and 248 nm. Analysis of these data shows that the overall growth rate determines the nitrogen composition, and suggests that a surface reaction between carbon and nitrogen represents a key step in the growth mechanism. Infrared spectroscopy has also been used to assess the phases present in the carbon nitride thin films. The implications of these results to the stoichiometry of covalent carbon nitride are discussed. ©1995 American Institute of Physics.