Journal Article

A strong electro-optically active lead-free ferroelectric integrated on silicon

Erni, Rolf, Abel, Stefan, Fompeyrine, Jean, Chelnokov, Alexei, Sousa, Marilyne, Offrein, Bert J., Stöferle, Thilo, Marchiori, Chiara, Caimi, Daniele, Rossel, Christophe, Rossell, Marta D.

2013

Overview

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. The strong electro-optical response of BaTiO 3 could be useful for making high-speed switches for optical telecommunications. Abel et al . demonstrate the ability to maintain this response in BaTiO 3 films grown directly onto silicon, extending its potential to the development of silicon photonics.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/301/119/996 / 639/624/1075/401 / 639/624/399/1099 / Barium / Ferroelectrics / Humanities and Social Sciences / Lithium / multidisciplinary / Optical properties / Science / Science (multidisciplinary) / Silicon / Thin films