Substrate Effects on the Microstructure and Mechanical Properties of SiO2 Thin Films

The SiO2 films deposited respectively on K9 and two different orientations of Y3Al5O12 (YAG) crystals were manufactured by electron beam technology. X-ray diffraction (XRD) and nano-scratch tests were used to demonstrate the microstructures and mechanical properties of films. The crystal orientation of SiO2 thin films on K9 is noncrystalline structure and the other two, YAG (100) and YAG (111), are polycrystalline structures. The Young modulus of all films are similar. The nano-scratch tests show that the damage mechanisms of SiO2 thin films on K9 and YAG are different. The adhesive forces of the films on YAG (100) and YAG (111) are much less than homologous film on K9. The microstructures of the films and the divergences of the elastic modulus between films and substrates are taken to explain the different mechanical behaviors of the films on three substrates.