The surface topography, structural and mechanical properties of Ge _{1 - X}C_x films prepared by magnetron co-sputtering

Non-hydrogenated germanium carbide (Ge_1-xC_x) films were prepared by magnetron co-sputtering method in a discharge of Ar. The surface topography, chemical bonding configurations and hardness were characterized by means of atomic force microscopy, X-ray photoelectron spectroscopy (XPS) and nanoindentation technique. The substrate temperature (T_s) exhibited important influence on the film surface topography. With the increase of T_s, the films became smoother owing to stronger diffusion. The film mass density varied between 4.40 g/cm³ and 4.47 g/cm³ depending on T_s. A progressive densification of the film microstructure occurred with T_s increasing. The XPS results showed that both the content of the GeGe bond and the content of the CGe bond in the films increased as T_s increased. The relationship between the chemical bonding and the mechanical properties of the Ge_{1 - x}C _x films was also explored. It showed that the hardness of the films increases from 7.47 GPa to 11.48 GPa as T_s increases from 200°C to 700°C. Therefore, increasing the substrate temperature led to a more dense and hard Ge_{1 - x}C_x film.