Improved leakage current density in Fe³⁺/Fe²⁺-doped epitaxially grown Ba_0.6Sr_0.4TiO₃ thin films based on the domain matching model

State Key Laboratory of High Performance Ceramics and Superfine Microstructures, Shanghai Institute of Ceramics, Chinese Academy of Sciences - 1295 Ding Xi Road, Shanghai, 200050, PRC

^(a) sddx320@163.com (corresponding author)

Received: 9 February 2014
Accepted: 8 May 2014

Abstract

A doping mode and its mechanism are proposed for Fe³⁺/Fe²⁺-doped (Ba,Sr)TiO₃ thin films of the perovskite structure (ABO₃), in which the substitutions of Fe³⁺/Fe²⁺ for the B site are coexisting to match the lattice distortion and release the strain energy, which is kind of like “domain matching”. Experimental results indicated that Fe dopant had little effect on the epitaxial growth of Ba_0.6Sr_0.4TiO₃ thin films, but had much effect on the suppression of defects such as oxygen vacancies, and the reduction of the leakage current density. With different Fe dopants, the Poole-Frenkel emission, the Schottky junction and the ohmic-like contact separately dominated the leakage current in different voltage regions.