Laser-induced physical vapour deposition of diamond-like carbon films

Abstract

Diamond-like carbon (DLC) films have been grown on various substrates at low temperatures and low pressure by ablation of carbon particles using KrF excimer laser pulses of 30 ns duration. It is shown that the film properties strongly depend on the energy density of the incident laser beam and the deposition temperature. At energy densities above 8 J cm −2 and low substrate temperatures (below 200°C), the coatings are transparent while, at lower energy densities or higher substrate temperatures, only opaque films are obtained. The thin films were characterized by optical spectroscopy, X-ray diffraction, Raman scattering and scanning electron microscopy. In addition to film growth and characterization, the kinetic energies and masses of laser-ablated carbon ions have been investigated by time-of-flight spectroscopy. We observe an almost linear relation between kinetic particle energy and laser energy density, with maximum values as high as 220 eV at 23 J cm −2, indicating a strong correlation between the laser energy density, the particle energies and the DLC film properties.