Effect of NiC layer thickness on the microstructure of magnetron-sputtered NiC/C multilayers

This study examined how the structural characteristics of NiC/C multilayer films prepared through magnetron sputtering change with different NiC layer thicknesses at the nanometer scale. When maintaining constant 3.0 nm carbon layers, the interfacial roughness expanded from 0.28 to 0.82 nm as the NiC layer thickness reduced from 5.1 to 1.0 nm. Particularly noticeable changes in interface roughness occurred when the NiC layers were thinner than 2.0 nm, which can be attributed to the random distribution of NiC crystalline structures. Two primary factors may explain this phenomenon: first, the non-uniform nucleation of NiC on amorphous carbon layers; second, the incorporation of C into Ni layers. Additionally, a crystal merging model was developed to demonstrate how NiC layer thickness variations influence crystalline dimensions during film deposition. The findings suggest that carbon integration into nickel layers enhances interface properties exclusively when the NiC layer exceeds the threshold thickness of 2.0 nm.