Integration Of Solution-Processed BaTiO3 Thin Films with High Pockels Coefficient on Photonic Platforms
: 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
Publisher: WILEY-V C H VERLAG GMBH
: WEINHEIM
: 2024
: Advanced Functional Materials
: ADVANCED FUNCTIONAL MATERIALS
: ADV FUNCT MATER
: 2403024
: 34
: 37
: 10
: 1616-301X
: 1616-3028
DOI: https://doi.org/10.1002/adfm.202403024
: https://doi.org/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 (r(eff)) of 139 pm V-1, and integration into a ring resonator-based modulator shows a V pi L 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.
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E.P. and E.L. contributed equally to this work. The authors thank Laura Van Bossele and Els Bruneel for performing the XRD (theta-2 theta) and XPS measurements, respectively. GIWAXS experiments were performed at the NCD-SWEET beamline at ALBA Synchrotron with the collaboration of ALBA staff. TEM measurements were performed by H.R. at the UGent TEM Core Facility. E.P. gratefully acknowledges the support and funding as an SB-PhD Fellow of the Research Foundation Flanders (FWO, grant number 3S041219). H.R. gratefully acknowledges the support and funding as a postdoctoral fellow in fundamental research by the Research Foundation Flanders (FWO, grant number 1273621N). P.P. acknowledges the Jenny and Antti Wihuri Foundation for the financial support. This work was financially supported by the Special Research Fund - UGent (BOF20/GOA/027).
