SiO₂–TiO₂ interfaces studied by ellipsometry and x-ray photoemission spectroscopy

We present an in situ study of the formation of the interfaces between TiO₂ and SiO₂ evaporated thin films using spectroscopic ellipsometry and x-ray photoemission spectroscopy (XPS). The growth of TiO₂ on SiO₂ was studied previously, but the reverse case has not received much attention up to now. In this article, we show that a common description is valid for both interfaces, which are formed by crosslinking Ti–O–Si bonds. We show also that the growth of TiO₂ on SiO₂ begins with an amorphous interface layer even when growth occurs at 400 °C. The interface is sharp, a few angstroms, as determined by angular XPS; when SiO₂ grows on TiO₂, the interface is thicker, about 10 Å. Roughness and interdiffusion play roles in interface formation and their role will be discussed. © 2002 American Institute of Physics.