Hard hydrogenated carbon films with low stress

Analysis of hard a-C:H films with low stress prepared by methane plasma dec omposition 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 lette r also supplies strong evidence that the subimplantation deposition model, used to explain the formation of ta-C and ta-C:H films, is also valid for a -C:H films deposited by methane plasma decomposition. It is proposed that t he rigidity of the films is basically provided by a matrix of dispersed cro ss-linked sp(2) sites, in addition to the contribution of the sp(3) sites. (C) 1998 American Institute of Physics. [S0003-6951(98)02431-0].