MicroRaman and microhardness study of nitrogen implanted diamond-like carbon films

Amorphous carbon films grown by PE-chemical vapour deposition have been implanted with nitrogen ions at room temperature, with an energy of 150 keV and doses up to 1 x 10(17) cm(-2). After implantation, the implanted region of the layers show structural inhomogeneities with sizes of approximately 100 mu m. The different regions in the layers (implanted and not implanted) have been analysed by Raman scattering and Microhardness measurements. The results obtained show that the film hardness in the inhomogeneous region exceeds approximately five times the hardness of the implanted region without inhomogeneities. This effect is related to the ion beam induced compaction of the film and to a structural transformation in the inhomogeneous region, as suggested by MicroRaman measurements. The appearance of the inhomogeneities with the implantation is likely to be related to the existence of local mechanical strains in the film. (C) 1998 Elsevier Science Ltd. All rights reserved.