Influence of carbon content and nitrogen vacancies on the bonding structure and mechanical performance of graphite-like BCxN thin films

X-ray absorption near edge structure (XANES) was used to investigate two sets of graphite-like BCxN thin films with similar B:C:N ratios but different amounts of nitrogen vacancies, which become oxygen-filled in the surface-most region. The two sets of samples were grown on Si (100) at room temperature by ion beam assisted deposition using two different ion/atom ratios. Nitrogen vacancy defects were detected in the B1s XANES spectra due to an oxygen decoration mechanism taking place at the film surface, which is correctly described by a core-level shift model. Analysis of the O1s XANES spectra showed two different types of oxygen incorporation in the samples under study. The tribomechanical properties of the BCxN samples were tested by the pin-on-disk technique, revealing the substantial role played by both the carbon intake in the hexagonal BCN planes and the concentration of nitrogen vacancies generated during the growth.