Ion-Sliced BaTiO 3 Thin Films: Structural and Optical Properties for Photonic Integration

High Resolution Image Download MS PowerPoint Slide Barium titanate (BaTiO 3 ) is a promising material for integrated photonics due to its large electro-optic and second-order nonlinear coefficients. Crystal ion slicing (CIS) enables the fabrication of thin BaTiO 3 films, but ion implantation introduces crystal damage and strain that can degrade their structural and optical quality. We investigate bulk BaTiO 3 subjected to low- and high-dose implantation as well as exfoliated CIS-processed flakes following thermal annealing. In bulk, ion implantation reorients ferroelectric domains from partially out-of-plane to fully in-plane polarization. Low doses relax the initial surface strain but do not enable exfoliation, whereas higher doses allow BaTiO 3 thin film release at the cost of increased crystalline disorder. Raman spectroscopy reveals that phonon coherence and crystallinity, key to electro-optic performance, are restored only after thermal recovery, while second-harmonic generation microscopy shows that CIS-exfoliated flakes retain ferroelectric order and χ (2) activity even before annealing. Thermal annealing further reorganizes the ferroelectric domain structure underlying the χ (2) nonlinear response and returns the optical dispersion into close agreement with that of bulk BaTiO 3 . The results suggest that optimized CIS processing can yield optically nonlinear and electro-optically active films suitable for integrated photonics, with an accessible thickness range that surpasses what is achievable with epitaxial growth methods.