STUDY OF NITROGEN PRESSURE EFFECT ON THE LASER-DEPOSITED AMORPHOUS-CARBON FILMS

The series of amorphous carbon films (a-C) deposited at a vacuum of 2x 10(-3) Pa and nitrogenated amorphous carbon films (a-CN) deposited at different nitrogen pressures were grown by the pulsed laser deposition method. The influence of the molecular nitrogen pressure in the depos ition chamber on the film properties was investigated. Electrical resi stivity, intrinsic stress and UV-Vis transmission of the films were me asured for this purpose. The optical bandgap was calculated from the a bsorption edge of the UV-Vis spectra. Changes of the structure, of the chemical bonding and of the stoichiometry were investigated using Ram an spectroscopy, X-ray photoelectron spectroscopy, and Rutherford back scattering spectroscopy respectively. Carbon nitride formation was ind icated. The promotion of the sp(2) bonding is indirectly indicated by Raman spectroscopy. A rapid enhancement of electrical resistivity of s amples deposited at nitrogen pressure p(N) above 5 Pa was observed. We concluded that two contradictory effects result in non-monotonous dep endence of the electrical resistivity and optical bandgap on the nitro gen pressure p(N): graphitization and carbon nitride formation. The hi gh compressive stress decreased with increasing nitrogen pressure p(N) and it even changed to tensile stress above 5 Pa. Formation of the vo ids in the structure is discussed.