Symmetric pulse-enabled highly linear analog switching in ALD-grown HfO2/Ta2O5-based memristor for multi-level storage and synaptic applications

Analog memristors with multilevel cells are suitable for analog in-memory and neuromorphic applications. Herein, we report a 2-bit/cell complementary-metal-oxide-semiconductor (CMOS)-compatible HfO 2 /Ta 2 O 5 bilayer memristor with both TiN electrodes fabricated via single thermal atomic layer deposition at 300 °C. The fabricated devices exhibit stable bipolar switching characteristics distinguished between both low resistance state and the high resistance state with a P/E endurance of 10 5 WRITE cycles, as well as show better retention property beyond 10 4 s. The devices exhibited excellent uniformity in terms of low device-to-device (D2D) and low cycle-to-cycle (C2C) variation. Furthermore, analog switching responses are implemented with the pulse width from 2 ms to 500 µs, and the corresponding percentage change in the device resistance was measured. The results exhibit a significant change in the device resistance even at 500 µs, with an overall change in the device resistance in the range of 10%–17%. In addition, the performance of the devices has been verified for neuromorphic applications using the experimentally extracted data. The non-linearity of 0.07, including highly stable synaptic plasticity, has been achieved using symmetric pulses, making the devices compatible for designing an analog memristor-based neuromorphic computing system hardware.