Effect of thermal treatment on resistive switching characteristics in Pt/Ti/Al2O3/Pt devices

Resistive switching characteristics of Pt/Ti/Al2O3/Pt memory devices annealed at various temperatures including 400 °C, 500 °C and 600 °C for 1 h under ambient condition were investigated in the study. The Al2O3 thin films annealed at up to 600 °C for 1 h remain amorphous phase based on the X-ray diffraction (XRD) analyses. As increasing annealing temperature, the forming voltage (activating the pristine device) of the memory device decreases in contrast to the rising trend of the turn-on voltage (switching from high to low resistance state). However, the turn-off voltage (switching from low to high resistance state) is almost uninfluenced by thermal annealing. These phenomena might be attributed to the interdiffusion between Ti and Al2O3, based on the analyzed results of secondary ion mass spectroscopy (SIMS) and high resolution transmission electron microscope (HR-TEM). Moreover, the thermal annealing process eventually creates high conducting paths with a high density of oxygen vacancies between the two electrodes.