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Turning electrical switching behaviors in WO <sub/><i>x</i> </sub> thin films by thickness
摘要： The tunability of electrical switching behaviors in WOx thin films were investigated in this paper. Electrical responses of the WOx films were observed to be highly sensitive to the film thickness. As the film thickness increases from 50 to 100 nm, the switching behavior changes from complementary resistive switching (CRS) to threshold switching (TS). A defect-related dynamic evolution of filament is responsible for the switching behavior. Such a controllable electrical switching can well broaden the application of the WOx thin film.
关键词： threshold switching,WOx thin film,Electrical switching behavior,turning,complementary resistive switching
更新于2025-09-23 15:23:52
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Performance-Enhancing Selector via Symmetrical Multilayer Design
摘要： Two-terminal selectors with high nonlinearity, based on bidirectional threshold switching (TS) behaviors, are considered as a crucial element of crossbar integration for emerging nonvolatile memory and neuromorphic network. Although great efforts have been made to obtain various selectors, existing selectors cannot fully satisfy the rigorous standard of assorted memristive elements and it is in great demand to enhance the performance. Here, a new type of Ag/TaOx/TaOy/TaOx/Ag (x < y) selector based on homogeneous trilayered oxides is developed to attain the required parameters including bidirectional TS operation, a large selectivity of ≈1010, a high compliance current up to 1 mA, and ultralow switching voltages under 0.2 V. Tunable operation voltages can be realized by modulating the thickness of inserted TaOy. All-TaOx-based integrated 1S1R (one selector and one memristor) cells, prepared completely by magnetron sputtering and no need of a middle electrode, exhibit a nonlinear feature, which is quite characteristic for the crossbar devices, avoiding undesired crosstalk current issues. The tantalum-oxide-based homojunctions offer high insulation, low ion mobility, and rich interfaces, which is responsible for the modulation of Ag conductive filaments and corresponding high-performance cation-based selector. These findings might advance practical implementation of two-terminal selectors in emerging memories, especially resistive random access memories.
关键词： conductive filaments,1S1R,multilayers,threshold switching,TaOx,selector
更新于2025-09-23 15:23:52
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Threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes with high temperature stability
摘要： This letter reports the observation of threshold switching and memory behaviors of epitaxially regrown GaN-on-GaN vertical p-n diodes. This mechanism was ascribed to the conductive path formed by traps in the insulating layer at the regrowth interface after soft breakdown. The device can reliably switch more than 1000 cycles at both room temperature and 300 oC with small fluctuation on the set and reset voltage. The set voltage increased with the increasing temperature due to the enhanced thermal detrapping effect that made it harder to form conductive path at high temperatures. Besides, the device showed memory behaviors when the reset voltage was higher than 4.4 V. This work can serve as important references to further developing GaN-based memory devices and integrated circuits.
关键词： memory,breakdown,wide bandgap semiconductor,threshold switching,p-n diodes,Gallium nitride
更新于2025-09-23 15:22:29
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Firing voltage reduction in thermally annealed Gea??Asa??Te thin film with ovonic threshold switching
摘要： Recently, chalcogenide materials have exhibited ovonic threshold switching characteristics, improving their suitability as selector devices to effectively depress the sneak current in the cross-point array (CPA) structures. However, chalcogenides must be subjected to a firing process before they can exhibit the threshold switching behavior. The firing process causes operation problems with respect to the memory operation process in the case of the CPA structure. Although the firing process is expected to be related to Joule heating with a high electric current, the physical nature of the changes during the firing process remains unclear. In this study, selector devices are fabricated by sandwiching amorphous Ge–As–Te thin films between the TiN and W layers. Furthermore, the authors examine the microstructure of the Ge–As–Te thin films before and after the electric firing process using transmittance electron microscopy (TEM, JEOL JEM-F200). The TEM analysis of the pristine Ge–As–Te thin films denotes the uniform contrast of the image, which implies the uniform chemical composition of the film. However, the Ge–As–Te thin films exhibit nonuniform contrast due to the effects of Joule heating after the electric firing process. The Ge–As–Te thin films were thermally annealed at 150 and 250 °C for 1 min via the rapid thermal annealing process to verify the effects of thermal treatment on the firing process in chalcogenide thin films. The effect of thermal annealing on the threshold switching behavior was also investigated by studying the compositional stability. Their results showed that the thermal annealing process caused the uniform compositions on the pristine Ge–As–Te films to be fluctuated with decreasing firing voltage for threshold switching.
关键词： Ge–As–Te thin films,chalcogenide materials,thermal annealing,ovonic threshold switching,firing process
更新于2025-09-23 15:21:01
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Research on Temperature Effect in Insulator-Metal Transition Selector Based on NbO? Thin Films
摘要： In this paper, the NbOx, which was regarded as a promising material based on its insulator–metal transition (IMT) effects, was applied as the switching layer of the device. The threshold switching characteristics were comprehensively investigated with particular emphasis on temperature dependence. The conduction mechanism for high-resistance state (HRS) was ?tted and veri?ed to be Schottky emission. With the increase in temperature, the ?tting results demonstrated that the Schottky barrier decreased, leading to a reduction in the resistance of HRS. Furthermore, according to Fourier’s law of heat conduction, the ?uctuation range of temperature was smaller, causing a narrow distribution of the threshold voltage as the operating temperature increased. In addition, the increasing temperature caused high energy of electrons, which would induce an IMT more easily, leading to a lower threshold voltage. This paper provided the promise for improving the thermal stability of selected devices.
关键词： selector,Insulator–metal transition (IMT),threshold switching (TS),Schottky emission
更新于2025-09-23 15:21:01
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Trap-controlled space-charge-limited conduction in amorphous As <i> <sub/>x</sub></i> Te <sub/> 1a?? <i>x</i> </sub> thin films with ovonic threshold switching
摘要： Ovonic threshold switching (OTS) in chalcogenide materials has attracted considerable interest for application in electronic devices to suppress leakage current in cross-point array structures. Although OTS appears to originate from an electronic process, the exact mechanism of OTS remains unclear with respect to sub-threshold conduction and threshold switching. In this study, we demonstrated that the sub-threshold conduction characteristics is affected by the structures of the exponentially distributed trap states in amorphous chalcogenide materials. Using binary AsxTe1?x thin films, we investigated the effects of trap distribution on OTS characteristics, analyzed the band structures, and developed a trap-controlled space-charge-limited conduction model.
关键词： Ovonic threshold switching,space-charge-limited conduction,amorphous AsxTe1?x thin films,chalcogenide materials
更新于2025-09-23 15:19:57
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Optically Modulated Threshold Switching in Corea??Shell Quantum Dot Based Memristive Device
摘要： The threshold switching (TS) phenomenon in memristors has drawn great attention for its versatile applications in selectors, artificial neurons, true random number generators, and electronic integrations. The transition between nonvolatile resistive switching and volatile TS modes can be realized by doping, varying annealing and voltage sweeping conditions, or imposing different compliance current. Here, a strategy is reported to achieve such transition by the noninvasive UV light stimulus based on InP/ZnS quantum dot (QD) memristor. The core–shell InP/ZnS QDs with quasi-type II band alignment ensures photoexcited electrons localized in InP core, photoexcited hole state distributed in the outer shell, and subsequent lifetime controlling of conductive filament under light irradiation. Systematic mechanism investigations indicate that UV photogenerated holes are accumulated on the surface of the QD film, which is consistent with rapid transfer of photogenerated holes in the core–shell InP/ZnS structure. Based on the light-modulated effect, a reconfigurable 9 × 9 visual data storage array with a key pattern and a simple leaky integrate-and-fire circuit are constructed. These results suggest the potential of direct optical modulation of memory mode through energy band engineering, leading to future optoelectronic and electronic device for the implementation of neuromorphic visual system and artificial neural networks.
关键词： quantum dots,light modulation,volatile threshold switching
更新于2025-09-23 15:19:57
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Ovonic threshold switching in polycrystalline zinc telluride thin films deposited by RF sputtering
摘要： Chalcogenide materials of the amorphous phase with low band gaps were reported to show Ovonic threshold switching (OTS), making them suitable for selection devices in cross-point memory arrays. Herein, we report that ZnTe films with polycrystalline structures show OTS behavior. Nearly stoichiometric ZnTe thin films were deposited by an RF sputtering method. X-ray diffraction analysis indicated that the films were polycrystalline. The optical band gaps of the ZnTe films were estimated as 2.2 eV from UV-visible spectroscopy transmittance measurements. Photoluminescence measurements indicated the existence of deep-level defects in the ZnTe thin films. Although these ZnTe films have a polycrystalline structure with a relatively high band gap, I-V profiles show OTS characteristics, with a selectivity of over 104, fast threshold switching time in the sub-10 ns scale, and thermal stability up to 400°C. ZnTe also shows switching endurance for more than 109 cycles without Vth drift, maintaining its selectivity of 104. Thus, we improved the threshold switching characteristics by using a wide-band-gap and polycrystalline-structured ZnTe-based chalcogenide material. Post-annealing experiments indicated that the thermal budget of the ZnTe thin film was sufficient for stacked cross-point array structures, thereby overcoming a previous limitation of chalcogenide switching materials. This material is promising for application in high-density cross-point memory arrays as the selection device.
关键词： crystalline,ovonic threshold switching,selection device,thermal stability,zinc telluride
更新于2025-09-19 17:15:36
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Origin of Current‐Controlled Negative Differential Resistance Modes and the Emergence of Composite Characteristics with High Complexity
摘要： Current-controlled negative differential resistance has significant potential as a fundamental building block in brain-inspired neuromorphic computing. However, achieving the desired negative differential resistance characteristics, which is crucial for practical implementation, remains challenging due to a lack of consensus on the underlying mechanism and design criteria. Here, a material-independent model of current-controlled negative differential resistance is reported to explain a broad range of characteristics, including the origin of the discontinuous snap-back response observed in many transition metal oxides. This is achieved by explicitly accounting for a non-uniform current distribution in the oxide film and its impact on the effective circuit of the device rather than a material-specific phase transition. The predictions of the model are then compared with experimental observations to show that the continuous S-type and discontinuous snap-back characteristics serve as fundamental building blocks for composite behavior with higher complexity. Finally, the potential of our approach is demonstrated for predicting and engineering unconventional compound behavior with novel functionality for emerging electronic and neuromorphic computing applications.
关键词： negative differential resistance,neuromorphic computing,threshold switching,nonlinear transport,nanoelectronics
更新于2025-09-19 17:13:59
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Chemical Vapor Deposited Vanadium Pentoxide Nanosheets with Highly Stable and Low Switching Voltages for Effective Selector Devices
摘要： Recently, attempts to overcome the physical limits of memory devices have led to the development of promising materials and architectures for next-generation memory technology. The selector device is one of the essential ingredients of high-density stacked memory systems. However, complicated constituent deposition conditions and thermal degradation are problematic, even with effective selector device materials. Herein, we demonstrate the highly stable and low threshold voltages of vanadium pentoxide (V2O5) nanosheets synthesized by facile chemical vapor deposition, which have not been previously reported on the threshold switching properties. The electrons occupying trap sites in poly-crystalline V2O5 nanosheet contribute to the perfectly symmetric threshold switching feature at the bias polarity and low threshold voltages in V2O5, confirmed by high-resolution transmission electron microscopy measurements. Furthermore, we find an additional PdO interlayer in V2O5 nanodevices connected with a Pd/Au electrode after thermal annealing treatment. The PdO interlayer decreases the threshold voltages, and the Ion/Ioff ratio increases because of the increased trap density of V2O5. These studies provide insight into V2O5 switching characteristics, which can support low power consumption in non-volatile memory devices.
关键词： nanosheets,selector devices,vanadium pentoxide,threshold switching,thermal annealing treatment
更新于2025-09-10 09:29:36