NEW FORMS OF HYDROGEN-FREE AMORPHOUS-CARBON FILMS

Amorphous carbon films free of hydrogen, deposited at room temperature by magnetron sputtering, were found to exhibit amorphous diamond char acter. The films were studied during deposition with real time and in situ spectroscopic ellipsometry (SE), from which the transparency, spe ctral dependence and composition were determined. Raman spectroscopy a nd X-ray reflectivity were also used to investigate the film type, bon ding formation and density. In addition, stress measurements conducted with the cantilever technique prove that the internal stresses in the films are compressive and above 4 GPa. The results from the above tec hniques show thar films rich in sp(3) C-C bonds are dense, highly stre ssed and metastable. These films do nor exhibit in Raman spectra the c haracteristic G and D bands of DLC films, but instead a new band appea rs at about 1120 cm(-1). This band disappears when the spectra are rec orded with higher laser intensities and the film undergoes a phase tra nsformation. Electron diffraction patterns obtained from specimens aft er chemical etching reveal amorphous highly deformed sp(2) and sp(3) C -C sites, whereas the same specimens prepared with Ar ion bombardment exhibit polycrystalline diamond structure. (C) 1998 Elsevier Science L td. All rights reserved.