Improved resistive switching characteristics of a multi-stacked HfO 2 /Al 2 O 3 /HfO 2 RRAM structure for neuromorphic and synaptic applications: experimental and computational study.

Atomic Layer Deposition (ALD) was used for a tri-layer structure (HfO ₂ /Al ₂ O ₃ /HfO ₂ ) at low temperature over an Indium Tin Oxide (ITO) transparent electrode. First, the microstructure of the fabricated TaN/HfO ₂ /Al ₂ O ₃ /HfO ₂ /ITO RRAM device was examined by the cross-sectional High-Resolution Transmission Electron Microscopy (HRTEM). Then, Energy Dispersive X-ray Spectroscopy (EDS) was performed to probe compositional mapping. The bipolar resistive switching mode of the device was confirmed through SET/RESET characteristic plots for 100 cycles as a function of applied biasing voltage. An endurance test was performed for 100 DC switching cycles @0.2 V wherein; data retention was found up to 10 ⁴ s. Moreover, for better insight into the charge conduction mechanism in tri-layer HfO ₂ /Al ₂ O ₃ /HfO ₂ , based on oxygen vacancies (V _OX ), total density of states (TDOS), partial density of states (PDOS) and isosurface three-dimensional charge density analysis was performed using WEIN2k and VASP simulation packages under Perdew-Burke-Ernzerhof _Generalized Gradient approximation (PBE-GGA). The experimental and theoretical outcomes can help in finding proper stacking of the active resistive switching (RS) layer for resistive random-access memory (RRAM) applications.
Competing Interests: There are no conflicts to declare.
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