We compared the resistive switching performances of built-in graded oxygen concentration
TaO x films and uniform TaO x films under the 100 μA compliance current. The device with a
graded oxygen concentration demonstrates increased low resistance and high resistance
states, as well as improved stability without the need of higher switching voltages. Using the
pulse mode, the switching voltages were confirmed to be less than 1.0 V for the pulse widths
of 100 ns and 50 ns and less than 3.3 V for that of 10 ns, showing great advantages over …