Enhancement of adhesion strength and corrosion resistance of nitrogen or platinum/ruthenium/nitrogen doped diamond-like carbon thin films by platinum/ruthenium underlayer

A platinum/ruthenium (PtRu) underlayer was grown on highly conductive p-Si (100) substrates, on which nitrogen doped diamond-like carbon (N-DLC) thin films without or with incorporation of Pt and Ru (PtRuN-DLC) were deposited, both via a DC magnetron sputtering system. The effect of PtRu underlayer on the bonding structure, surface morphology and adhesion strength of the N-DLC and PtRuN-DLC films was investigated using X-ray photoelectron spectroscopy (XPS) and micro-Raman spectroscopy, atomic force microscopy (AFM) and micro-scratch testing, respectively. The effect of the PtRu underlayer on the corrosion performance of these films in a 0.1 M HCl solution was diagnosed using electrochemical impedance spectroscopy (EIS). Although the incorporation of Pt and Ru into the N-DLC films promoted sp² sites in the films via metal-induced graphitization, the PtRu underlayer along with the incorporation of Pt and Ru in the N-DLC films could enhance the charge transfer resistance of the films, indicating the increased corrosion resistance of the films.