Polarity dependence of forming step on improved performance in Ti/HfOx/W with dual resistive switching mode

- Coexistence of unipolar/bipolar resistive switching in Ti/HfOx/W is investigated.
- Ti/HfOx/W in the negative voltage exhibit arbitrary switching mode transition.
- An improved uniformity of memory window for the device with positive forming.
- The asymmetric O in the HfOx is responsible for the dual resistance switching.
- A plausible dual resistance switching mechanism is proposed.