Phosphorus doping and defect studies of diamnond-like carbon films by pulsed laser deposition using camphoric carbon target

Phosphorous is doped in diamond-like carbon (DLC) films by pulsed (XeCl) laser deposition technique using a camphoric carbon (CC) target, obtained from burning camphor (C10H16O), a natural source. The activation energy of undoped film is approximately 0.17 eV and increased to approximately 0.23 eV for the film deposited from the target containing 1% P. With a further increase of P content, the activation energy decreases to approximately 0.12 eV for the film deposited from the target containing 7% P. Study of activation energy reveals that the Fermi level of the carbon film moves from the valence band edge to near the conduction band edge through the mid-gap. The Tauc gap, conductivity, activation energy together with electron spin resonance (ESR) spectroscopic studies reveal successful doping of P in the films deposited from target containing up to 5% P upon modifications in the gap states. (C) 2001 Elsevier Science B.V. All rights reserved.