Microstructural analysis and electro-optic properties of thick epitaxial BaTiO3 films integrated on silicon (001)

Recent advances in epitaxial oxide deposition have enabled the fabrication of thick films of ferroelectric perovskite ${\mathrm{BaTiO}}_{3}$ capable of providing a robust electro-optic response via the Pockels effect in silicon photonic devices. We report a microstructure analysis of such films integrated on Si(001) by molecular beam epitaxy, showing how the crystallographic and polarization orientation change as a function of thickness. The measured electro-optic properties of the film correlate well with the microstructural analysis and demonstrate the potential of Si-integrated ${\mathrm{BaTiO}}_{3}$ for silicon photonics. An effective Pockels coefficient of up to 268 pm/V has been demonstrated in 110-nm-thick films in transmission measurements and 352 pm/V in waveguide measurements.