Comprehensive classification of DLC films formed by various methods using NEXAFS measurement

Structural analysis was performed on the 55 kinds of diamond-like carbon (DLC) films. The ratio of sp(2) hybridized carbon in the film, sp(2)/(sp(2) + sp(3)) ratio, was determined by the carbon K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy using synchrotron radiation in the soft Xray region. In addition, hydrogen content in the DLC film was determined by elastic recoil detection analysis (ERDA) using an electrostatic accelerator. Furthermore, the density of the DLC film was measured by X-ray reflectivity method. Analyzed DLC films were divided broadly into four groups. Group 1 was characterized by high density, low sp(2)/(sp(2) + sp(3)) ratio and low H content. Group 2 was characterized by low density, high sp(2)/(sp(2) + sp(3)) ratio and low H content. Group 3 was characterized by medium density, and medium sp(2)/(sp(2) + sp(3)) ratio and relative high H content. Most samples in the present study were belonging to this group. Group 4 was characterized by low sp(2)/(sp(2) + sp(3)) ratio in spite of low density. H contents of samples in this group were relatively high. (c) 2008 Elsevier B.V. All rights reserved.