HARD HYDROGENATED CARBON-FILMS WITH LOW-STRESS

Analysis of hard a-C:H films with low stress prepared by methane plasm a decomposition is reported. Films with hardness as high as 14 GPa and stress as low as 0.5 GPa were obtained. These films have a high Raman I-d/I-g ratio (similar to 1.0), and small Tauc's band gap (similar to 0.4 eV). This letter also supplies strong evidence that the subimplan tation deposition model, used to explain the formation of la-C and ta- C:H films, is also valid for a-C:H films deposited by methane plasma d ecomposition. It is proposed that the rigidity of the films is basical ly provided by a matrix of dispersed cross-linked sp(2) sites, in addi tion to the contribution of the sp(3) sites. (C) 1998 American Institu te of Physics.