Effect of laser power density and deposition temperature on electrical and optical properties of pulsed laser ablated diamond-like carbon films O

Amorphous diamond-like carbon (DLC) thin films were deposited by pulsed laser ablation using an XeCl excimer laser and a pyrolytic graphite target. The effect of the laser power density and the substrate temperature on the optical and electrical properties of the films was studied. It was found to be possible to tailor the electrical and optical properties of the deposited films between diamond-like and graphite-like by varying the peak power density of the laser beam and the deposition temperature. The optical band gap of the films varied from zero (deposition temperature ≥200°C) to a maximum value of 1.35 eV. The real part n of the visible wavelength refractive index ranged from 2.4 to 2.5 for good quality DLC films. It was possible to vary the electrical conductivity by eight orders of magnitude between DLC and graphite-like material. The conductivity of the DLC films exhibited an exp(−T−1/4) dependence on temperature that is characteristic of hopping mechanisms; graphite-like films showed more band-type conductivity.