The chemical composition of as-grown and surface treated amorphous boron carbon thin films by means of NEXAFS and XPS

Boron carbon (BC) thin film alloys have been grown using the technique of plasma enhanced chemical vapor deposition. The electronic and chemical properties of the boron carbon thin films have been investigated with the techniques of near edge X-ray absorption fine structure spectroscopy and X-ray photoemission spectroscopy. The spectroscopic data indicates that the chemical bonding of the BC alloys is very similar to that of single crystal boron carbide. However, the lack of long-range order, i.e. amorphous structure, of the BC alloys shifts the B 1s and C 1s core level states relative to single crystal boron carbide, indicative of ionization states associated with defects. Comparison of the π∗ and σ∗ states across the C 1s absorption edge of the BC films with those of diamond and graphite indicates that the carbon bonding is predominantly sp3 in character. Boron bonding is a mixture of sp2 and sp3 hybridization based on comparisons with c- and h-boron nitride.