Relaxation in photo-induced conductivity of polycrystalline BiFeO₃ film

¹ College of Science and Technology, North China Electric Power University, 071051 Baoding, P.R. China
² College of Physics Science and Technology, Hebei University, 071002 Baoding, P.R. China

^a e-mail: btliu@mail.hbu.edu.cn

Received: 29 December 2014
Revised: 25 April 2015
Accepted: 15 May 2015
Published online: 14 August 2015

Abstract

Polycrystalline BiFeO₃ (BFO) film is deposited on Pt(1 1 1)/Ti/SiO₂/Si(0 0 1) substrate via magnetron sputtering. Integrated Pt/SrRuO₃ (SRO) are used to be top electrode to produce the Pt/SRO/BFO/Pt thin film capacitor. The remanent polarization is 59.5, 69.3, 77 and 89.8 μC/cm² measured at 22.5, 25, 27.5 and 30 V, respectively. The photoconductivity is reported in BFO film under the illumination by the 5 mW/cm² purple light of 404 nm. It is found that the leakage current density in purple light displays the tendency of decline with the increased illumination times, which can be explained by the recombination and capture of the photo-induced charges by the ionized vacancies. The relaxation time for the illuminated leakage current density reaching the steady state is 210 and 570 s at positive and negative bias, respectively. The obtained large relaxation time at negative bias is considered to be that negative bias is in the same direction as the SRO/BFO interface field.