Structural and mechanical properties of ta-C films grown by pulsed laser deposition

Diamond-like carbon (DLC) films have been prepared by pulsed laser deposition (PLD) (wavelength 248 nm), ablating highly oriented pyrolytic graphite (HOPG) at room temperature in a vacuum of 10(-2) Pa, at fluences between 0.5 and 35 J cm(-2). Films have been deposited on Si(100) with and without a ceramic interlayer, namely SiC, TiC, or TiN. Structural analysis with Raman and infrared spectroscopy shows that the films are hydrogen free and undergo a transition from mainly disordered graphitic to up to 84% tetrahedral amorphous carbon (ta-C) above a laser threshold fluence of 5 J cm(-2), corresponding to 2.5 x 10(8) W cm(-2) Nanoindentation indicates that film hardness is as high as 70 GPa. The measured residual stresses do not exceed 2 GPa. Scratch tests show excellent adhesion properties of films deposited on SiC. Friction coefficients as low as 0.05 have been measured.