Growth and Properties of Carbon Nitride Thin Films

Recent research on carbon nitride thin films grown using pulsed laser deposition combined with atomic beam techniques is reviewed. The composition, growth mechanism and phases of these films 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 nm and 248 nm wavelengths. Time of flight mass spectroscopy investigations of the ablation products have shown that the fluence variations affect primarily the yield of the carbon reactant. These experiments demonstrate that the overall film growth rate determines the average nitrogen composition, and furthermore, suggest that a key step in the growth mechanism involves a surface reaction between carbon and nitrogen. Infrared spectroscopy has been used to assess the phases present in the carbon nitride thin films as a function of the overall nitrogen content. These measurements have shown that a cyanogen-like impurity occurs in films with nitrogen compositions greater than 30%. Studies of thermal annealing have shown, however, that this impurity phase can be eliminated to yield a single phase C2N material. In addition, systematic studies of the electrical resistivity and thermal conductivity of the carbon nitride films are discussed.