Non-destructive characterization of mechanical and structural properties of amorphous diamond-like carbon films

Abstract

Amorphous diamond-like carbon (DLC) films show promising properties for wear protection applications. Pulsed laser deposition (PLD), laser-induced pulsed vacuum arc deposition (laser-arc) and mass-selected ion beam deposition (MSIBD) are techniques which enable deposition of DLC films with the desired properties by providing sufficiently high carbon energy. Two non-destructive methods were used to determine the properties of films deposited by these three deposition techniques: (1) ellipsometry, which gives information about the micro-structure through the optical properties; and (2) laser-acoustic analysis enabling the measurement of the Young's modulus of thin films down to less than 100 nm film thickness. These methods were used to investigate the effect of the carbon ion energy and the substrate temperature during deposition on the film quality. A clear correlation between the Young's modulus and the optical parameters was found. All three deposition techniques are characterized by a critical substrate temperature above which sp 2 rich films are deposited. The PLD and MSIBD systems have a higher ion energy and a lower deposition rate than the laser-arc system. This is the reason for the higher critical substrate temperature below which sp 3 rich films are formed for PLD and MSIBD compared with laser-arc.