The effect of high resistivity AlOδ layer on low-power consumption of TaOx based resistive switching memory

Two top electrode (TE) metals, Al and Ta, were deposited on TaOx/Pt to investigate the effect of different interfacial states between TE and TaOx on resistive switching (RS). During TE metals deposition, 4-nm-thick AlO delta interface layer (IL) formed in situ in Al/TaOx/Pt, whereas no IL formed in Ta/TaOx/Pt. The AlOd IL acts as a series resistor (R-S) rather than an RS layer. Therefore, Al/TaOx/Pt can suppress voltage or current overshoot effect during the set process owing to the IL voltage-division effect. The high R-s (AlO delta: 60 k Omega) may facilitate the formation of a finer conductive filament, allowing the Al/TaOx/Pt sample to be set under an ultra-low current (similar to 5 mu A). In contrast, Ta/TaOx/Pt requires a much larger current (similar to 5 mA). Although the power consumption is low, the endurance performance of Al/TaOx/Pt is not good enough. During repeated RS, the oxygen ions in TaOx are consumed to oxidize TE Al owing to the high oxygen affinity of Al. This process causes an increase in the oxygen vacancy concentration of TaOx, reducing the durability of Al/TaOx/Pt. Therefore, the series IL not only functions as a voltage divider but can also exchange oxygen ions with the RS layer, which significantly influences the low power consumption and high-endurance.