Structural and mechanical characterization of diamond like carbon films grown by microwave plasma CVD

Abstract

Diamond like carbon (DLC) films is useful for tribology, optical and biocompatible coating applications. Plasma-activated processes such as radio frequency (RF) plasma CVD and electron cyclotron resonance (ECR) microwave (MW) plasma CVD are usually used to grow DLC films. By using a bowl shaped steel substrate holder in a 3 kW MW plasma CVD reactor (without ECR), DLC films have been grown at relatively high pressure using CH(4), H(2) and Ar gas mixture. Raman spectra of the grown films show typical G (1580 cm(-1)) and D (1350 cm(-1)) bands and transmission electron microscopy (TEM) image show nanocrystalline structure, further, FTIR and UV-visible spectra show presence of hydrogenated sp(3) polymeric carbon and high visible transmittance (similar to 85%) of the films. These films show reasonable mechanical properties (hardness around 6-16 GPa and Young's modulus 160-200 GPa) and have smooth surface morphologies as revealed by atomic force microscope (AFM) having rms roughness value about 3 nm. These films show polymeric DLC characteristics, which may be useful as anti-corrosion and scratch-resistant coatings. (C) 2010 Elsevier B.V. All rights reserved.