Epitaxy of SrTiO₃ on Silicon: The Knitting Machine Strategy

SrTiO₃ (STO) crystalline layers grown on Si open unique perspectives for the monolithic integration of functional oxides in silicon-based devices, but their fabrication by molecular beam epitaxy (MBE) is challenging due to unwanted interfacial reactions. Here we show that the formation of single-crystal STO layers on Si by MBE at the moderate growth temperature imposed by these interface reactions results from the crystallization of a partially separated amorphous mixture of SrO and TiO₂ activated by an excess of Sr. We identify the atomic pathway of this mechanism and show that it leads to an antiphase domain morphology. On the basis of these results, we suggest and test alternative STO growth strategies to avoid antiphase boundary formation and significantly improve the STO structural quality. The understanding provided by these results offers promising prospects to crystallize perovskite oxides on semiconductors at moderate temperature and circumvent the issue of parasitic interface reactions.