Pulsed laser deposition and physical properties of carbon nitride thin films

Carbon nitride thin films were grown using an approach that combines pulsed laser deposition and atomic beam techniques. The composition and phases of the carbon nitride materials obtained from the reaction of laser ablated carbon and atomic nitrogen have been systematically 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 and 248 nm. Analysis of these experiments show that the growth rate determines the overall nitrogen composition, and thus suggests that a key step in the growth mechanism involves a surface reaction between carbon and nitrogen. Infrared spectroscopy has also been used to assess the phases present in the carbon nitride thin films. This spectroscopic measurement indicates that a cyanogen-like impurity occurs in films with nitrogen compositions greater than 30%. Investigations of the effects of thermal annealing have been carried out, and show that the impurity phase can be eliminated to yield a single phase material. In addition, systematic measurements of the electrical resistivity and thermal conductivity of the carbon nitride films were made as a function of nitrogen content. The implications of these results are discussed.