Thickness dependent structural evolution in Mg-Zn-Ca thin film metallic glasses

Mg-Zn-Ca thin film metallic glasses were prepared by using direct current magnetron sputtering and their film thickness dependences of density, morphology and local atomic structure were systematically investigated. It is found that all the films prepared are fully amorphous. The film density and the coordination number around Zn atoms decrease while the surface roughness increases with increasing film thickness. When the film thickness is larger than the critical value of 400 nm, the average atomic distance, the granular size on the film surface and the columnar size on the film cross-section remain almost unchanged, demonstrating that the films grow in an equilibrium mode.