CNx coatings sputtered by DC magnetron: hardness, nitrogenation and optical properties

CNx coatings were deposited by DC magnetron sputtering at lower constant N- 2 pressure 0.1 Pa. Nitrogenation of samples was controlled by increase in t he DC current. It led a decrease in the nitrogen content N/C in the films, but increased their microhardness. Evaluation of optical properties combini ng spectroscopic ellipsometry (1.5-4 eV) and the VUV reflection spectroscop y (4-14 eV) by means of Kramers-Kronig analysis showed increase of the pi-p lasmon resonance peak, which indicates enhancement of amount of pi-bonded e lectrons. It is linked with increase of sp2 hybridization. The optical ener gy gap values indicate semimetallic properties of the CNx films. A shift in the epsilon(2)(omega) maximum corresponding to sigma-sigma* electron trans itions in carbon demonstrates deeper band structure changes in highly nitro genated samples. (C) 1999 Elsevier Science S.A. All rights reserved.