Diamond-like carbon (DLC) and carbon nitride (CN) bilayer films with Al and AIN interlayer were fabricated by pulse cathode arc technique. The structure, composition, morphology and mechanical properties of the films were investigated by Raman, Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), Knoop sclerometer and surface profilometer. The results indicated that the complete diffusion between C and Al atoms occurs in the Al/DLC and AlICN, bilayer. Al interlayer induces the increase of the size and ordering of Csp(2) clusters in the films but AIN interlayer increases the disordering degree of Csp2 clusters. XPS results showed that a higher content of Csp(3)/Csp(2) bonds presents in the AlICN, bilayer, and Al and AIN interlayer decreases the atomic ratio of N/C. AFM with phase contrast mode illustrated the morphologic characteristics of the bilayer films. All the bilayers show a nano-structural surface. The morphology changes of the bilayer were well explained by the surface state of the substrate and the growth mechanism of DLC films. The hardness of Al/DLC bilayer decreases but it increases for the other bilayers compared to the corresponding DLC (CN) monolayer. The internal stress of the bilayer is significantly lower than that of the monolayer except for the AlNICN, bilayer. These studies could make the difference at the time of choosing a suitable functional film for certain application. (C) 2014 Elsevier B.V. All rights reserved.