Correlation between sp2/sp3 ratio or hydrogen content and water contact angle in hydrogenated DLC film

Abstract

Water contact angle has been measured to indirectly assess the Sp 2/sp3 ratio and hydrogen content of DLCH film under post N2 annealed treatment with O2 content under 100ppm. XPS spectrum is used to measure the C1s bonding type and calculate the sp 2/sp3 ratio. The surface morphology of DLCH film was examined by SEM and AFM. From experimental results, it seems the surface morphology was not a critical factor on water contact angle value, at least for DLCH film. A quantitative correlation between water contact angle and Sp 2/Sp3 ratio of DLCH film is established from which the hydrogen content can be estimated by the Sp2/Sp3 ratio as well as Angus equation. © 2007 The Japan Institute of Metals.