Rheological analysis of creep in hydrogenated amorphous carbon films

We present a nanoindentation study to detect time-dependent deformations in non-polymeric hydrogenated amorphous carbon films. When the bonded hydrogen content increases from 18 to 36 at.%, as measured by Fourier transform infrared spectroscopy, we find that the film becomes less graphitic and softer. Moreover, its hardness shows a larger sensitivity to strain rate and the film with the higher hydrogen content also exhibits a larger and slower creep deformation when subjected to a step-loading experiment. The creep data compares well to the Burgess model and we discuss the influence of Van der Waals bonds on the deformation of the carbon network. (c) 2006 Elsevier B.V. All rights reserved.