<title>Effect of technique parameters on characteristics of hydrogen-free DLC films deposited by surface wave-sustained plasma</title>

Abstract

Hydrogen-free diamond-like carbon (DLC) films were deposited by a new-type surface wave-sustained plasma physical vapor deposition (SWP-PVD) system under various technique conditions. Electron density was measured by a Langmuir probe, while the film thickness and hardness were characterized using a surface profilometer and a nanoindenter, respectively. Surface morphology was investigated by an atomic force microscope (AFM). It was found that the electron density and deposition rate increased following the increase in microwave power, target voltage, or gas pressure. The typical electron density and deposition rate were about 1.87-2.04×10¹¹ cm^-3 and 1.61-14.32 nm/min respectively. AFM images indicated that the grains of films changes as the technique parameters vary. The optical constants, refractive index <i>n</i> and extinction coefficient <i>k</i>, were obtained using an optical ellipsometry. With the increase in microwave power from 150 to 270 W, the extinction coefficient of DLC films increased from 0.05 to 0.27 while the refractive index decreased from 2.31 to 2.18.