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

• Published in: Advanced functional materials Vol. 34; no. 37
• Main Authors: Picavet, Ewout, Lievens, Enes, De Geest, Kobe, Rijckaert, Hannes, Fernandez, Edgar Gutierrez, Bikondoa, Oier, Solano, Eduardo, Paturi, Petriina, Singh, Nishant, Pannier, Tinus, Liu, Jiayi, Yin, Xin, Van Thourhout, Dries, Beeckman, Jeroen, De Buysser, Klaartje
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-09-2024
• Subjects: Barium titanates; chemical solution deposition; ferroelectric BaTiO3 film; Ferroelectric materials; Ferroelectricity; fiber textured films; heterogeneously integrated optical phase modulator; High vacuum; Integrated circuits; La2O2CO3 template film; Optical properties; Photonic crystals; Platforms; Pockels effect; Resonators; Silicon nitride; Substrates; Texture; Thin films; Vacuum deposition
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202403024

The heterogeneous integration of ferroelectric BaTiO3 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 BaTiO3 thin films on these platforms is far from trivial. So far, a conventional integration route using a SrTiO3 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 BaTiO3 films is needed. Therefore, an alternative method for the integration of highly textured BaTiO3 films using a La2O2CO3 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 BaTiO3 film are characterized and its integration into an optical ring resonator is evaluated. The BaTiO3 film exhibits a fiber texture, has a large Pockels coefficient (reff) of 139 pm V−1, and integration into a ring resonator‐based modulator shows a VπL of 1.881 V cm and a bandwidth of > 40 GHz. This enables low‐cost, high‐throughput, and flexible integration of BaTiO3 films on PIC platforms and the potential large‐scale fabrication of nanophotonic BaTiO3 thin‐film modulators.
Here, an alternative method is proposed for the integration of highly textured BaTiO3 films using a La2O2CO3 template film in combination with a chemical solution deposition (CSD) process. This process route enables the cost‐effective, high‐throughput and flexible processing of high‐quality heterogeneously integrated BaTiO3 phase modulators.