Study of SiO2/TiO2 and TiO2/SiO2 interfaces in the SiO2/TiO2/SiO2/c-Si prepared by cathodic pulverization radio frequency

The atomic structure of the TiO2/SiO2 and SiO2/TiO2 interfaces has been investigated in SiO2/TiO2/SiO2 multilayers deposited by radio frequency reactive sputtering without breaking the vacuum on the crystalline substrate cooled by water. The characterizations of these interfaces have been performed using three complementary techniques sensitive to surface and interface state: X-ray photoelectron spectroscopy (XPS), grazing incidence X-ray diffraction (GIXD), and specular X-ray reflectometry (GIXR). The concentration profiles and Si2p and O1s core level chemical displacements show that TiO2/SiO2 and SiO2/TiO2 interfaces are very diffuse. The reflectometry measurements confirm this character and indicate that the silicon, titanium, and oxygen atomic concentrations vary gradually at the interfaces. The grazing incidence X-ray spectra indicates that the interfacial layers are not well crystallized and are formed by SiO2-TiO2, TiO, Ti2O3, Ti3O5, Ti5Si3, Ti5Si4, TiSi, and TiSi2 components.