Pulsed laser deposition and modification of diamondlike 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 Jrcm2. The hydrogen-free films grown at high pulse energy densities above 6 Jrcm2 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 sp3-bonded. The maximum growth rate was as high as 120 nmrmin using 50 Hz laser pulse repetition rate. Hydrogen-free films grown at relatively low pulse energy density of 3.3 Jrcm2 showed optical bandgaps of 0.8 eV and refractive indices of 2.8 at 678.3 nm wavelength, the dispersion more resembling that of graphite. The films were completely amorphous and preferentially sp2-bonded. Furthermore, the influence of argon and nitrogen ion bombardment as well as excimer laser irradiation of the growing films was studied. q1998 Elsevier Science B.V.