X-Ray absorption studies of cubic boron-carbon-nitrogen films grown by ion beam assisted evaporation

We have synthesised boron carbon nitride (BCN) thin films with tetrahedral structure by evaporation of B,C and concurrent ion bombardment. The him structure and composition are characterised by infrared and X-ray absorption near edge (XANES) spectroscopies. The addition of Ar to the N-2 assisting gas is necessary to reach a momentum transfer above the threshold to promote tetrahedral bonding. Under these conditions, c-BCN compounds are achieved, but the carbon content is limited to similar to5 at.%, This phase grows on the top of a similar to 50-nm h-BCN layer oriented perpendicular to the substrate. The hexagonal BCN phase permits the accommodation of a carbon content between 10 and 15 at.%. The percentage of cubic and hexagonal phases is controlled by the temperature and ion assisting parameters. There is a narrow window for promoting the cubic structure with values similar to those reported for c-BN. (C) 2001 Elsevier Science B.V. All rights reserved.