Stress relaxation through thermal gradient structure of tetrahedral amorphous carbon thin film deposited on Ge–Se–Sb-based chalcogenide glass

Surface thermal gradient effects, which can improve interfacial adhesion between chalcogenide glasses and tetrahedral amorphous carbon (ta-C) films, are used to relax intrinsic stress at the ta-C deposition temperature. The intrinsic stress of ta-C is difficult to control through substrate bias voltage applied to the insulating substrate; however, under increased deposition temperatures, thermal stress is generated by the different thermal expansion coefficients of the ta-C film and the chalcogenide glass. Here, an ion source was used to increase the substrate temperature at the initial stage of deposition to simultaneously relax the thermal and intrinsic stresses. The 100-nm-thick ta-C coating film was applied by filtered cathodic vacuum arc deposition. The ta-C coating was deposited at varying surface temperatures. At the effective surface temperature of 80 °C, the adhesive strength exceeded 12.5 N/mm. In Raman and infrared (IR) transmittance spectral results, the I(D)/I(G) ratio was increased and the IR transmittance was decreased by 2%. [Display omitted] •Chalcogenide glass substrate temperature was modified before depositing ta-C film.•Higher initial substrate temperature led to better adhesion of deposited ta-C film.•Established thermal gradient eliminated internal and external stress in film.