Coexistence of unipolar and bipolar switching in nanocrystalline spinel ferrite ZnFe2O4 thin films synthesized by sol-gel method

Abstract

In this letter, we report the coexistence of unipolar and bipolar switching in a solution-based nanocrystalline spinel ferrite ZnFe2O4 thin film prepared by the sol-gel method. It is seen that the Au/ZnFe2O4/Pt device could be activated between unipolar and bipolar switching modes just by choosing RESET-voltage polarity. Conversions between unipolar to bipolar switching modes are reversible and controllable. The results show that the SET-voltage of unipolar switching is smaller than that of bipolar switching, while memory windows (ON/OFF ratio) are identical. Furthermore, filaments are induced by the migration of oxygen vacancies (VOs), which are responsible for reducing variations in SET voltages of unipolar switching. By analyzing the current transport conduction mechanism, the electrode-limited Schottky emission mechanism is dominated in the high field region. Temperature dependence of low and high resistance states indicates that conductive filaments are composed of VOs and metallic Zn atoms, involving Joule heating and electrochemical redox reaction effects. Investigation on coexisting both unipolar and bipolar switching modes in a single Au/ZnFe2O4/Pt memory cell would open a pathway for spinel ferrite based low-cost nonvolatile memory.

Recent Advances in Spinel Ferrite-Based Thin Films: Synthesis, Performances, Applications, and Beyond

“…The sol gradually turns into gel via the loss of fluid solvent during the aging process. Finally, the compounds are obtained through the calcination process (Ismail et al, 2018;Choueikani et al, 2021;Zhao et al, 2021).…”

Recent Progress in Solution‐Based Metal Oxide Resistive Switching Devices

“…[235] However, for certain active metals such as Al, a thick interfacial layer of oxide (AlO x ) can form on both electrodes, which leads to significant degradation during resistive switching operation by affecting the resistive switching layer's stoichiometry. [171] Asymmetrical devices are composed by two different electrodes and can have inert-inert (e.g., Pt-Au [265] ), inert-active (e.g., Pt-Al, [80] Pt-Ti, [266] Au-Al, [197] Pt-Ag, [87] Au-Ag, [156] and TaN-Cu [226] ), or (noninert)-active (e.g., Cu-Al, [177] Cu-Ag, [199] Ti-Cu, W-Al, [267] LNO-Al, [149] FTO-Ti, [73] FTO-Al, [201] ATO-Cu, [143] ITO-Ag, [192] ITO-Al, [148] and ITO-Ti [81] ) electrode structures. Figure 14 shows the reported metal oxide S-RRAMs with different configurations, symmetric and asymmetric structures.…”

“…2018 [265] ZnFe and then incorporated in p ++ -Si/HfO 2 /Cu resistive switching devices. [123] These exhibited an electroforming-free and bipolar resistive switching behavior and also a low variability, large resistance window (10 4 ), and suitable endurance end retention characteristics for radiation sensing.…”

Cation ratio and oxygen defects for engineering the magnetic transition of monodisperse nonstoichiometric zinc ferrite nanoparticles

“…Néel [19] predicted that the reducing particle size of the antiferromagnetic materials may induce ferromagnetism because of the uncompensated magnetic spins on the surface. Further, ZnFe 2 O 4 nanostructures with various morphological characteristics have been fabricated through different mechanisms, including coprecipitation [20], hydrothermal route [21], ball milling [22], sol-gel method [23], and thermal decomposition [14,18,24]. Anomalous superparamagnetism or ferromagnetism can be observed when the particle size is in the nanometer range [25].…”