In plane strained Barium Titanate thin films directly integrable on Silicon

Integrating ferroelectric materials onto Si is a critical part of the design new photonic devices such as optical modulators and switches. However, a difficult question to answer thus far has been how to optimize the crystalline orientation in these materials. One interesting material is Barium Titanate (BTO), because it exhibits the largest known Pockels effect which is the modulation of the refractive index by an electric field. However, many applications and device geometries require BTO with the polarization pointing in plane with the substrate, but so far it has proven difficult to optimize BTO to maximize in plane domains. Here, we present a method for the growth of single crystal BTO films that are entirely in plane and strain tunable. In this study, we use extensive X-ray characterization, TEM imaging and direct measurement of the Pockels coefficient in these films to show that the films are entirely in plane oriented BTO. This provides a method for high quality in plane oriented BTO to be directly integrated on Silicon.