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). The rmal gas evolution analysis has been used to gain insights about the v oid distribution. The effects of deposition parameters (self-bias volt age and nitrogen partial pressure in the plasma) on the film microstru cture were studied. The incorporation of increasing amounts of nitroge n originates an increase in void density as well as a progressive grap hitization 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 str ucture of these films with respect to those deposited at lower bias.