Thermal Stability of Epitaxial SrTiO$_{3}$ Thin Films on Si (001)

Epitaxial SrTiO$_{3}$ on Si(001) is important for application as a high $\kappa$ (Kappa) gate oxide and is also suitable as a buffer layer for the subsequent growth of other perovskite oxide thin films to enable integration of perovskite oxide functionality with Si. For the latter application, the thermal stability of the interface structure in epitaxial SrTiO$_{3}$ thin films grown by molecular-beam epitaxy on Si (001) becomes a key issue since most of the perovskite layers are grown at relatively high temperatures (750-850\r{ }C). SrTiO$_{3}$ and Si are intrinsically thermodynamically unstable in proximity to each other, with some reduction of the rTiO$_{3}$ and oxidation of the Si to be expected. We have used x-ray diffraction and micro-analytical techniques including optical microscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study the thermal stability of epitaxial SrTiO$_{3}$ thin films grown by molecular beam epitaxy (MBE) on Si (001). Elemental composition of the amorphous interface layer (AIL) and of the epitaxial SrTiO$_{3}$ film will change during various thermal treatments and gas environments encountered in the subsequent growth of other oxide layers.