Resistive switching and synaptic learning performance of TiO2 thin film based device prepared by sol-gel and spin coating technique.

Abstract

TiO2 thin film based devices of resistance random access memory (RRAM) was fabricated by sol-gel and spin coating technique. The composition, surface morphology, and microstructure of the TiO2 films were characterized by using X-ray diffraction (XRD), Raman, scanning electronic microscopy (SEM) and transmission electron microscopy (TEM) respectively. The fabricated Al/TiO2 film/FTO device exhibited electroforming-free bipolar resistive switching characteristics with a stable ON/OFF ratio higher than 300. The endurance cycling performance was still good after 100 direct sweeping cycles. A retention time of no less than 104 s was confirmed. Switching mechanism was systematically discussed based on the test results, and space-charge-limited current (SCLC) was found to be responsible for the switching behaviour. A multilevel memory performance was also realized in the as-fabricated devices. The synaptic performance was also investigated by applying consecutive positive (0 to 2V) and negative (0 to -1.6V) voltage sweeps. The fabricated devices were found to have learning-experience behaviour.