Research Article

Tuning the growth and strain relaxation of ferroelectric BaTiO₃ thin films on SrRuO₃ electrode: influence on electrical properties

¹ Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Université Paris-Saclay, C2N – Orsay, 91405 Orsay, France
² Laboratoire de Physique des Couches Minces et Matériaux pour l'Electronique (LPC2ME), Univ d'Oran1, Ahmed Ben Bella, Oran, Algeria

^* e-mail: amina.aidoud@c2n.upsaclay.fr

Received: 29 October 2011
Received in final form: 12 November 2017
Accepted: 5 December 2017
Published online: 30 January 2018

Abstract

This study is focused on the link between the structural and electric properties of BaTiO₃ thin films grown on SrRuO₃-buffered (001) SrTiO₃ substrates, SrRuO₃ acting as bottom electrode. The growth regime and film structure are here tuned through the growth pressure for pulsed laser deposition in the 1–200 mTorr range. The dielectric, ferroelectric and leakage current properties are systematically measured for the different strain states of the BaTiO₃ thin films on SrRuO₃. The results are discussed with the help of ab initio calculations on the effects of Ba- and Ti-vacancies on BaTiO₃ lattice parameters. A sharp increase of the dielectric constant is evidenced in the high pressure region, where the tetragonality of the BaTiO₃ is decreasing rapidly with growth pressure. We interpret this divergence of the dielectric function as the signature of the vicinity of the phase boundary between the out-of-plane and in-plane orientations of the tetragonal BTO films.