The Bipolar Resistive Switching in BiFeO3 Films

Pure-phase polycrystalline BiFeO₃ films have been successfully prepared by pulsed-laser deposition on surface oxidized Si substrates using LaNiO₃ buffer layer with substrate temperature (T _s) ranging from 550?°C to 800?°C and a laser frequency of 5?Hz and 10?Hz. Bipolar resistive switching has been observed in all the films using LaNiO₃ as bottom electrodes and silver glue dots as top electrodes, the resistivity switches from a high-resistance state (HRS) to a low-resistance state (LRS) with positive voltage applied on the top Ag electrodes, and from LRS to HRS with positive voltage applied on the bottom LaNiO₃ electrodes. The mechanism of the resistive switching has been confirmed to be due to the voltage polarity dependent formation/rupture of the conducting filaments formed by the O vacancies. The highest resistive ratio of HRS to LRS, of more than 2 orders of magnitude, has been achieved in the highest resistive BiFeO₃ film prepared at T _s of 650?°C and laser frequency of 10?Hz.