Reactive magnetron sputtering of germanium carbide films at different substrate temperature

To explore the relationship between the chemical bonding and mechanical properties for germanium carbide （Ge1-xCx ） films, the Ge1-xCx films are prepared via reactive magnetron sputtering in a mixture of CH4/ Ar discharge, and their composition, chemical bonding and hardness were investigated as a function of substrate temperature （Ts）. The results show that Ts remarkably influences the chemical bonding of Ge1-xCx film, which results in a pronounced change in the film hardness. As Ts increases from ambient （60 ℃ ） to 500 ℃ , the Ge content in the film gradually increases, which promotes forming sp3 C-Ge bonds in the film at the expense of sp2C-C bonds. Furthermore, it is found that with increasing Ts the fraction of C -H bonds in Ge1-xCx film gradually decreases, which is attributed to an enhancement in the desorption rate of C - Hn （ n = 1, 2, 3 ） species decomposed from methane. The transition from graphite-like sp2 C - C to diamond-like sp^3 C-Ge bonds as well as the reduction in C - H bonds in the film with increasing Ts promotes forming the compact three-dimensional network structure, which significantly enhances the hardness of the film from 5.8 to 10. 1 GPa.