The interface of epitaxial SrTiO3 on silicon: in situ and ex situ studies

The formation of interfacial layers between silicon and the overgrown epitaxial ${\mathrm{SrTiO}}_3$ as a function of the growth temperature has been studied in detail using x-ray photoelectron spectroscopy and high-resolution transmission electron microscopy. Models for the chemical compositions and atomic bonding states have been established. With a good understanding of the mechanisms of the interfacial layer formations, the molecular-beam epitaxy growth process can be well controlled to form high-quality, single-crystalline oxide films, as well as a desired interface between the grown oxide and silicon substrate. The epitaxial relationship has been found to be ${\mathrm{SrTiO}}_3$ $\text{(001)∥}\mathrm{Si}\text{(001),}$ and ${\mathrm{SrTiO}}_3$ $\text{〈100〉∥}\mathrm{Si}\text{〈110〉.}$