Enhancing the nonvolatile properties of sol-gel-processed Y2O3 RRAM devices by suppressing oxygen vacancy formation

초록

In this study, Y2O3-based resistive random-access memory (RRAM) devices with an Ag/Y2O3/indium tin oxide structure are fabricated on a glass substrate via sol-gel processing. These Y2O3 RRAM devices demonstrate typical bipolar resistance-switching characteristics without requiring a high-voltage forming process. The presence of oxygen vacancies in the metal-oxide layers alters the electrical properties of these devices. To control the oxygen vacancy concentration, the post-annealing temperatures are varied between 300 and 500 degrees C. As this temperature increases, the concentration of formed oxygen vacancies decreases. The RRAM devices annealed at 500 degrees C feature a reduced number of oxygen vacancies in Y2O3, initially exhibiting the highest high-resistance state. This yields the highest high-to low-resistance state ratio exceeding 10(5). Moreover, the Y2O3 RRAM devices annealed at 500 degrees C exhibit the highest number of endurance cycles (similar to 10(3)) and good data-retention times (similar to 10(4) s). In addition, the reduced oxygen vacancy concentration in these annealed Y2O3 films suppresses the excessive formation of conductive filaments in the low-resistance state and decreases the leakage current in the high-resistance state. Overall, these changes yield a high-to low-resistance state ratio and improved endurance characteristics owing to the reduced oxygen vacancy concentration in the Y2O3 films annealed at 500 degrees C.

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