Laser deposition of diamondlike carbon films at high intensities

Unhydrogenated diamondlike carbon ~DLC! thin films have been deposited by laser ablation of graphite, using a high power Ti: sapphire solid state laser system. DLC films were deposited onto silicon substrates at room temperature with subpicosecond laser pulses, at peak intensities in the 4310– 5310 W/cm range. A variety of techniques, including scanning and transmission electron microscopy ~SEM and TEM!, Raman spectroscopy, spectroscopic ellipsometry ~SE!, and electron energy loss spectroscopy ~EELS! have been used to analyze the film quality. Smooth, partially transparent films were produced, distinct from the graphite target. Sp volume fractions were found to be in the 50%–60% range, with Tauc band gaps ranging from 0.6 to 1.2 eV, depending on laser intensity. Kinetic energies carried by the carbon ions in the laser induced plasma were measured through time-of-flight ~TOF! spectroscopy. Their most probable kinetic energies were found to be in the 700–1000 eV range, increasing with laser intensity. © 1995 American Institute of Physics.