Integration Of Solution‐Processed BaTiO3 Thin Films with High Pockels Coefficient on Photonic Platforms

Abstract The heterogeneous integration of ferroelectric BaTiO 3 thin films on silicon (Si) and silicon nitride (SiN)‐based platforms for photonic integrated circuits (PICs) plays a crucial role in the development of future nanophotonic thin film modulators. Since the electro‐optic (EO) properties of ferroelectric thin films strongly depend on their crystal phase and texture, the integration of BaTiO 3 thin films on these platforms is far from trivial. So far, a conventional integration route using a SrTiO 3 template film in combination with high vacuum deposition methods has been developed, but it has a low throughput, is expensive and requires monocrystalline substrates. To close this gap, a cost‐efficient, high‐throughput and scalable method for integrating highly textured BaTiO 3 films is needed. Therefore, an alternative method for the integration of highly textured BaTiO 3 films using a La 2 O 2 CO 3 template film in combination with a chemical solution deposition (CSD) process is presented. In this work, the structural and EO properties of the solution‐processed BaTiO 3 film are characterized and its integration into an optical ring resonator is evaluated. The BaTiO 3 film exhibits a fiber texture, has a large Pockels coefficient ( r eff ) of 139 pm V −1 , and integration into a ring resonator‐based modulator shows a V π L of 1.881 V cm and a bandwidth of > 40 GHz. This enables low‐cost, high‐throughput, and flexible integration of BaTiO 3 films on PIC platforms and the potential large‐scale fabrication of nanophotonic BaTiO 3 thin‐film modulators.