Diamond like carbon coatings deposited by microwave plasma CVD: XPS and ellipsometric studies

Abstract

Diamond-like carbon (DLC) films were deposited by microwave assisted chemical vapour deposition system using d.c. bias voltage ranging from -100 V to -300 V. These films were characterized by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry techniques for estimating sp 3/sp2 ratio. The sp3/sp2 ratio obtained by XPS is found to have an opposite trend to that obtained by spectroscopic ellipsometry. These results are explained using sub-plantation picture of DLC growth. Our results clearly indicate that the film is composed of two different layers, having entirely different properties in terms of void percentage and sp3/sp2 ratio. The upper layer is relatively thinner as compared to the bottom layer. © Indian Academy of Sciences.