STRUCTURAL CHARACTERIZATION OF AMORPHOUS HYDROGENATED CARBON AND CARBON NITRIDE FILMS DEPOSITED BY PLASMA-ENHANCED CVD

Microstructural investigations of a-C:H and a-CNx:H films obtained by plasma-enhanced CVD were performed by means of Raman spectroscopy and positron annihilation spectroscopy (Doppler-broadening technique). Thermal gas evolution analysis has been used to gain insights about the void distribution. The effects of deposition parameters (self-bias voltage and nitrogen partial pressure in the plasma) on the film microstructure were studied. The incorporation of increasing amounts of nitrogen originates an increase in void density as well as a progressive graphitization of a-C:H films. Raman scattering from a-C:H films deposited at self-bias voltages higher than -800 V reveals a more graphitic structure of these films with respect to those deposited at lower bias.