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 A degrees C to 800 A degrees 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 A degrees C and laser frequency of 10 Hz.