Fig. 2 (a) The I-t and V-t curves under triangle pulses (5.8 V, 10
ms). (b) Potentiation and depression process by positive pulses (5.8 V,
5 ms) and negative pulses (-4 V, 5 ms).
The multi-level states modulation capability of self-rectifying
Pt/HZO/TiN device is shown in Fig. 2. The I-t and V-tcurves of Pt/HZO/TiN device under triangle pulses (5.8 V, 10 ms) are
shown in Fig. 2a . The gradual increase of response current
demonstrates the potential for multi-level modulation. Then, the
identical rectangle pulses (5.8 V, 5 ms) for potentiation and (-4 V, 5
ms) for depression are employed to further investigate the device
performance. It should be noted that all the current was readout at the
same read pulse (3 V, 5 ms). As seen from Fig. 2b , the read
current was gradually tuned up by 50 potentiation pulses and down by 50
depression pulses. The above results confirm the good gradual switching
properties of self-rectifying Pt/HZO/TiN device under both potentiation
and depression pulses, which can be used to mimic the synaptic behaviors
in brain-inspired computing systems.