title: A strong electro-optically active lead-free ferroelectric integrated on silicon.
abstract: The development of silicon photonics could greatly benefit from the linear electro-optical properties, absent in bulk silicon, of ferroelectric oxides, as a novel way to seamlessly connect the electrical and optical domain. Of all oxides, barium titanate exhibits one of the largest linear electro-optical coefficients, which has however not yet been explored for thin films on silicon. Here we report on the electro-optical properties of thin barium titanate films epitaxially grown on silicon substrates. We extract a large effective Pockels coefficient of r(eff) = 148 pm V(-1), which is five times larger than in the current standard material for electro-optical devices, lithium niobate. We also reveal the tensor nature of the electro-optical properties, as necessary for properly designing future devices, and furthermore unambiguously demonstrate the presence of ferroelectricity. The integration of electro-optical active films on silicon could pave the way towards power-efficient, ultra-compact integrated devices, such as modulators, tuning elements and bistable switches.
authors.affiliation: IBM Research-Zurich, 8803 Rüschlikon, Switzerland. sab@zurich.ibm.com
authors.forename: Stefan
authors.initials: S
authors.lastname: Abel
authors.forename: Thilo
authors.initials: T
authors.lastname: Stöferle
authors.forename: Chiara
authors.initials: C
authors.lastname: Marchiori
authors.forename: Christophe
authors.initials: C
authors.lastname: Rossel
authors.forename: Marta D
authors.initials: MD
authors.lastname: Rossell
authors.forename: Rolf
authors.initials: R
authors.lastname: Erni
authors.forename: Daniele
authors.initials: D
authors.lastname: Caimi
authors.forename: Marilyne
authors.initials: M
authors.lastname: Sousa
authors.forename: Alexei
authors.initials: A
authors.lastname: Chelnokov
authors.forename: Bert J
authors.initials: BJ
authors.lastname: Offrein
authors.forename: Jean
authors.initials: J
authors.lastname: Fompeyrine