Electrical Analysis of Atomic Layer Deposited Thin HfO₂ and HfO₂/Ta₂O₅-Based Memristive Devices

Here, we report the detailed fabrication and electrical analysis of atomic layer deposited single (i.e., HfO₂) and bilayer (i.e., HfO₂/Ta₂O₅)-based memristive devices. The bilayer devices show stable retention properties >103 s with an improved ON/OFF ratio. Moreover, the bilayer devices also exhibit higher change in the device resistance (25%–30%) as compared to resistance change (∼12%) in single-layer devices under the same electrical programming scheme. The least values of coefficient of variability (CV) in cycle-to-cycle (C2C) in the device resistance states are 0.19% low-resistance state (LRS) and 0.28% high-resistance state (HRS) for single-layer device, while in the case of bilayer devices, these values are 1.10% (LRS) and 0.29% (HRS). Furthermore, the impedance spectroscopy (EIS) analysis reveals that the switching mechanism is more dominant due to the change in the device resistance rather than the device capacitance. Therefore, this work opens a new way to further explore the ac analysis of memristive devices and their potential applications in various fields.