CNX COATINGS SPUTTERED BY DC MAGNETRON : HARDNESS, NITROGENATION AND OPTICAL PROPERTIES

Abstract CN x coatings were deposited by DC magnetron sputtering at lower constant N 2 pressure 0.1 Pa. Nitrogenation of samples was controlled by increase in the DC current. It led a decrease in the nitrogen content N/C in the films, but increased their microhardness. Evaluation of optical properties combining spectroscopic ellipsometry (1.5–4 eV) and the VUV reflection spectroscopy (4–14 eV) by means of Kramers–Kronig analysis showed increase of the π-plasmon resonance peak, which indicates enhancement of amount of π-bonded electrons. It is linked with increase of sp 2 hybridization. The optical energy gap values indicate semimetallic properties of the CN x films. A shift in the e 2 (ω) maximum corresponding to σ–σ∗ electron transitions in carbon demonstrates deeper band structure changes in highly nitrogenated samples.