Optical properties of a-C and a-C:H diamond-like films prepared by high power excimer laser ablation

The amorphous carbon films have many superior properties such as high hardness, high wear resistance, low coefficient of friction, etc., making them suitable for many applications so that many studies have focused on the synthesis and characterization of carbon coatings, in the past years. The films can be prepared by different techniques, among them was pulsed laser deposition (PLD) which has attracted much attention mainly due to the good quality film it produces. In this work amorphous carbon ( a-C) and a-C: H films were deposited by high frequency and high power pulsed XeCl excimer laser ablation of pyrolytic graphite targets at room temperature. The effect of the laser power density and the pressure of hydrogen atmosphere on the optical properties of the films were studied by setting the laser peak power density on the target at 10(8), 10(9) and 10(10) W/cm(2), respectively, and the pressure of the hydrogen was 0, 2, 20 and 50 Pa while the laser density at 10(10) W/cm(2). Raman spectra as well as the UV and IR transparency, were used for film analysis. The results indicate that the optical property of the films was improved with the increase of the laser power density and the hydrogen pressure, respectively. The reason was demonstrated according to the pulsed laser deposition mechanism.