PULSED-LASER DEPOSITION AND MODIFICATION OF DIAMOND-LIKE CARBON-FILMS

Diamondlike carbon (DLC) films were prepared by pulsed laser ablation from a polycrystalline graphite target using an KrF-excimer laser beam , where the pulse energy density was varied in the range of 2 to 8 J/c m(2). The hydrogen-free films grown at high pulse energy densities abo ve 6 J/cm(2) showed optical bandgaps of 1.8 eV and refractive indices of 2.60 at 678.3 nm wavelength having similar dispersion like that of diamond. The films were completely amorphous and preferentially sp(3)- bonded. The maximum growth rate was as high as 120 nm/min using 50 Hz laser pulse repetition rate. Hydrogen-free films grown at relatively l ow pulse energy density of 3.3 J/cm(2) showed optical bandgaps of 0.8 eV and refractive indices of 2.8 at 678.3 nm wavelength, the dispersio n more resembling that of graphite. The films were completely amorphou s and preferentially sp(2)-bonded. Furthermore, the influence of argon and nitrogen ion bombardment as well as excimer laser irradiation of the growing films was studied. (C) 1998 Elsevier Science B.V.