Electrical Analysis of Atomic Layer Deposited Thin HfO<sub>2</sub> and HfO<sub>2</sub>/Ta<sub>2</sub>O<sub>5</sub>-Based Memristive Devices
Sanjay Kumar, Deepika Yadav, Rahul Ramesh, Spyros Stathopoulos, Andreas Tsiamis, Themis Prodromakis
Abstract
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 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\gt 10^{{3}}$ </tex-math></inline-formula> s with an improved <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small>/<sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> 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 (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C} _{\text {V}}$ </tex-math></inline-formula>) 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.