Correlation between Electronic Structure, Microstructure, and Switching Mode in Valence Change Mechanism Al₂O₃/TiO_x‐Based Memristive Devices

Abstract

Memristive devices with valence change mechanism (VCM) show promise for neuromorphic data processing, although emulation of synaptic behavior with analog weight updates remains a challenge. Standard filamentary and area‐dependent resistive switching exhibit characteristic differences in the transition from the high to low resistance state, which is either abrupt with inherently high variability or gradual and allows quasi‐analog operation. In this study, the two switching modes are clearly correlated to differences in the microstructure and electronic structure for Pt/Al2O3/TiOx/Cr/Pt devices made from amorphous layers of 1.2 nm Al2O3 and 7 nm TiOx by atomic layer deposition. For the filamentary mode, operando spectromicroscopy experiments identify a localized region of ≈50 nm in diameter of reduced titania surrounded by crystalline rutile‐like TiO2, highlighting the importance of Joule heating for this mode. In contrast, both oxide layers remain in their amorphous state for the interfacial mode, which proves that device temperature during switching stays below 670 K, which is the TiO2 crystallization temperature. The analysis of the electronic conduction behavior confirms that the interfacial switching occurs by modulating the effective tunnel barrier width due to accumulation and depletion of oxygen vacancies at the Al2O3/TiOx interface. The results are transferable to other bilayer stacks.

Light-Mediated Multilevel Flexible High-Efficiency Perovskite Resistive Switching Memory Based on Mn:CsPbCl3 Nanocrystals

“…Subsequently, the filamentary conduction mechanism has been confirmed by the statistical distribution of LRS and HRS on the dependence of different device areas, as shown in Figure b. Neither LRS nor HRS values showed a linear dependence on the electrode area, confirming the conductive filamentary behavior. − To further investigate the metallic conductive filament mechanism of the PMMA&Mn:CsPbCl 3 based devices, we fabricated the Au/PMMA&Mn:CsPbCl 3 /ITO devices and tested the electrical properties, as shown in Figure S4. The analyses presented above show that the resistive switching mechanism is dominated by the formation and the rupture of the Ag conductive filaments.…”