ECR sputtering and electron/ion alternative irradiation for multilayer carbon films fabrication with tunable layer thickness

In this work, we proposed a method of electron cyclotron resonance (ECR) sputtering and electron/ion alternative irradiation to form multilayer carbon films with different single layer thicknesses. The soft electron irradiated layers and protective ion irradiated layers were deposited as the component layers. The transmission electron microscopy (TEM) and Raman spectra proved that the graphene sheets structure in electron irradiated layers could be preserved in multilayer carbon films. We found a rule of the dependence of the surface roughness, mechanical and tribological properties of the multilayer films on the single layer thickness. With the decrease of single layer thickness, the surface roughness decreased and the mechanical and tribological properties improved notably. The mechanisms of the long wear life with low friction coefficient were further discussed based on the hardness enhancement and the cracking length limitation. This work indicated that by decreasing the single layer thickness, ECR sputtering and electron/ion alternative irradiation can fabricate films with combined properties of the component materials, which can be expected for broad nanolayered surface science and engineering applications.