X-Ray absorption studies of cubic boron-carbon-nitrogen films grown by ionbeam 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 str ucture and composition are characterised by infrared and X-ray absorption n ear edge (XANES) spectroscopies. The addition of Ar to the N-2 assisting ga s 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 sub strate. The hexagonal BCN phase permits the accommodation of a carbon conte nt between 10 and 15 at.%. The percentage of cubic and hexagonal phases is controlled by the temperature and ion assisting parameters. There is a narr ow window for promoting the cubic structure with values similar to those re ported for c-BN. (C) 2001 Elsevier Science B.V. All rights reserved.