Si-Integrated BaTiO3 for Electro-Optic Applications: Crystalline and Polarization Orientation Control

Recent research has demonstratedthat BaTiO3 epitaxiallygrown on Si is capable of a large electro-optical response via thePockels effect crucial for fabricating efficient phase modulatorsin integrated silicon photonics. However, the typical crystallographicorientation evolution of epitaxial BaTiO3 on SrTiO3-buffered Si yields a dead layer (a region of the film witha low electro-optic response) for most device geometries. We reporton a Si-on-insulator-integrated film stack incorporating a MgO bufferlayer that effectively alleviates this problem. The film quality isconfirmed with crystallographic characterization; electro-optic measurementsyield an effective Pockels coefficient of 119 pm/V for a 100 nm thickfilm.