Multilevel resistive switching in solution-processed CuFe2O4/TiO2 heterostructure

Low-cost, stable, and easy-to-fabricate resistive switching memory (RSM) devices are highly desirable for next-generation nonvolatile memories. Spinel-structured CuFe2O4 (CFO), composed of earth-abundant, environmentally friendly elements, is a multifunctional material mainly featuring super-paramagnetism. This work explores the potential of spin-coated CFO thin films as an active material in RSM. A simple fluorine-doped tin oxide (FTO)/CFO/Ag device shows a bipolar resistive switching behavior with the problems like scattered SET and RESET voltages and endurance deterioration. Adding a TiO2 layer in the conventional device, we overcame the above limitations and achieved additional advantages of multilevel switching and improved temperature stability. The solution-processed FTO/TiO2/CFO/Ag bilayer device shows stable endurance with a maximum ON/OFF ratio of 100 with the ability to have multiple high resistance states and exhibits excellent temperature stability up to 250 °C. Our results further enhance the multifunctionality of CFO with the potential of being low-cost multilevel RSM.