Enhanced unipolar resistive switching in substituted Bi(Fe0.95Mn0.05)O3 bilayer films

Abstract

In this work, Bi(Fe0.95Mn0.05)O3 (BFMO) and 15% Pr-substituted BFMO (BPFMO) thin films are prepared by chemical solution deposition. Unipolar resistive switching is achieved in both Pt/BFMO/Pt and Pt/BFMO/BPFMO/Pt thin-film capacitors as a result of the formation and rupture of conductive filaments that consist of positively charged oxygen vacancies. The Pt/BFMO/Pt capacitor exhibits a resistance ratio of ∼40 between the high and the low resistance states, in which the programming voltages are 3.1 and 4.5 V, respectively, for the Reset and the Set processes. The resistive switching properties can be significantly enhanced by inserting a BPFMO thin layer between the BFMO and the bottom Pt electrode. In the Pt/BFMO/BPFMO/Pt capacitor, not only is the resistance ratio increased by more than two orders of magnitude, up to ∼5 × 103, but also the Reset and Set voltages are drastically reduced to ∼0.8 and ∼2.6 V, respectively. The possible mechanisms of the enhancement in overall resistive switching are discussed in terms of the reduced concentration of oxygen vacancies in the BPFMO layer, which results in the controllable formation/rupture of conductive filaments in the Pt/BFMO/BPFMO/Pt capacitor.