Raman characterization of amorphous carbon films

Amorphous carbon films, deposited with the LASER-ARC technique, were characterized using Raman scattering experiments at an excitation wavelength of 633 nm provided by a He-Ne laser. To distinguish between the homogeneous amorphous film and incorporated particles spatial resolved measurements have been carried out with a laser spot diameter of 1 pm. Typical diamond-like films, grown near room temperature, show a broad Raman band between 1000 cm(exp-1) and 1800 cm(exp-1) that can be fitted by two gaussian distributions very well. Films deposited at higher substrate temperatures reveal more and more graphitic features in the spectra. The spectra of particles consists of a graphite-like fraction originated by the graphitic structure of the particle and a diamond-like portion caused by the covering DLC film. The degree of disorder and diamond-likeness in the film structure is quantified by the peak position, the free width at half maximum (FWHM) and intensity relation of the fitted "D"- an d "G"-peaks. Additional to Raman experiments investigations of the morphology of the DLC film and embedded particles by AFM, TEM, electron diffraction and EELS were carried out