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Trapped charge modulation at the MoS2/SiO2 interface by lateral electric field in MoS2 field-effect transistors
摘要： Controlling trapped charges at the interface between a two-dimensional (2D) material and SiO2 is crucial for the stable electrical characteristics in field-effect transistors (FETs). Typically, gate-source bias has been used to modulate the charge trapping process with a narrow dielectric layer with a high gate electric field. Here, we observed that charge trapping can also be affected by the lateral drain-source voltage (VDS) in the FET structure, as well as by the gate-source bias. Through multiple VDS sweeps with increasing measurement VDS range, we demonstrated that the charge trapping process could be modulated by the range of the applied lateral electric field. Moreover, we inserted hexagonal boron nitride (h-BN) layer between the MoS2 and SiO2 layer to explore the charge trapping behavior when a better interface is formed. This study provides a deeper understanding of controlling the electrical characteristics with interface-trapped carriers and lateral electrical fields in 2D materials-based transistors.
关键词： charge trapping,high electric fields,MoS2,field-effect transistors
更新于2025-09-23 15:23:52
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Near-Infrared Annihilation of Conductive Filaments in Quasiplane MoSe <sub/>2</sub> /Bi <sub/>2</sub> Se <sub/>3</sub> Nanosheets for Mimicking Heterosynaptic Plasticity
摘要： It is desirable to imitate synaptic functionality to break through the memory wall in traditional von Neumann architecture. Modulating heterosynaptic plasticity between pre- and postneurons by another modulatory interneuron ensures the computing system to display more complicated functions. Optoelectronic devices facilitate the inspiration for high-performance artificial heterosynaptic systems. Nevertheless, the utilization of near-infrared (NIR) irradiation to act as a modulatory terminal for heterosynaptic plasticity emulation has not yet been realized. Here, an NIR resistive random access memory (RRAM) is reported, based on quasiplane MoSe2/Bi2Se3 heterostructure in which the anomalous NIR threshold switching and NIR reset operation are realized. Furthermore, it is shown that such an NIR irradiation can be employed as a modulatory terminal to emulate heterosynaptic plasticity. The reconfigurable 2D image recognition is also demonstrated by an RRAM crossbar array. NIR annihilation effect in quasiplane MoSe2/Bi2Se3 nanosheets may open a path toward optical-modulated in-memory computing and artificial retinal prostheses.
关键词： 2D materials,charge trapping,quasiplane nanosheets,near-infrared annihilation,heterostructures
更新于2025-09-23 15:22:29
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Understanding Temperature-Dependent Charge Extraction and Trapping in Perovskite Solar Cells
摘要： Understanding the factors that limit the performance of perovskite solar cells (PSCs) can be enriched by detailed temperature (T)-dependent studies. Based on p-i-n type PSCs with prototype methylammonium lead triiodide (MAPbI3) perovskite absorbers, T-dependent photovoltaic properties are explored and negative T-coefficients for the three device parameters (VOC, JSC, and FF) are observed within a wide low T-range, leading to a maximum power conversion efficiency (PCE) of 21.4% with an impressive fill factor (FF) approaching 82% at 220 K. These T-behaviors are explained by the enhanced interfacial charge transfer, reduced charge trapping with suppressed nonradiative recombination and narrowed optical bandgap at lower T. By comparing the T-dependent device behaviors based on MAPbI3 devices containing a PASP passivation layer, enhanced PCE at room temperature is observed but different tendencies showing attenuating T-dependencies of JSC and FF, which eventually leads to nearly T-invariable PCEs. These results indicate that charge extraction with the utilized all-organic charge transporting layers is not a limiting factor for low-T device operation, meanwhile the trap passivation layer of choice can play a role in the T-dependent photovoltaic properties and thus needs to be considered for PSCs operating in a temperature-variable environment.
关键词： temperature dependence,charge trapping,recombination,charge extraction,passivation layer
更新于2025-09-23 15:21:01
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Enhanced memory characteristics of charge trapping memory by employing graphene oxide quantum dots
摘要： In this study, graphene oxide quantum dots (GOQDs) are embedded in the charge trapping layer of high-k material HfO2 for nonvolatile memory applications. The fabricated devices exhibit a large memory window of (cid:2)1.57 V under a 63.5 V applied sweeping voltage and show only (cid:2)13.1% of charge loss after a retention time of 1.2 (cid:3) 104 s. This excellent performance is attributed to the quantum well formed in the charge trapping layer. Defect traps in the HfO2 ?lm enhance the charge trapping ef?ciency and retention property of fabricated devices. This work implies that GOQDs embedded in high-k materials are promising for charge trapping memory applications.
关键词： nonvolatile memory,graphene oxide quantum dots,HfO2,charge trapping memory
更新于2025-09-23 15:19:57
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High voltage endurance and switchable resistance effect observed in nanoscale copper groove structure
摘要： A switchable lateral resistance effect with high reverse voltage has been observed in nanoscale copper groove structure. With the stimulation of electric pulse and local illumination of laser, the lateral resistance of the structure can be modulated in a non-volatile manner. We attribute this phenomenon to the different width of depletion region and the Schottky barrier change caused by the nanoscale charge trapping effect. This work may inspire new approach of resistance modulation and help the development of laser-assisted electric pulse merged devices.
关键词： photoelectric effect,charge trapping effect,Schottky barrier
更新于2025-09-19 17:15:36
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CMOS 256-Pixel/480-Pixel Photovoltaic-Powered Subretinal Prosthetic Chips With Wide Image Dynamic Range and Bi/Four-Directional Sharing Electrodes and Their Ex Vivo Experimental Validations With Mice
摘要： After nearly half a century of research into the bias temperature instability, two classes of models have emerged as the strongest contenders. One class of models, the reaction-diffusion models, is built around the idea that hydrogen is released from the interface and that it is the diffusion of some form of hydrogen that controls both degradation and recovery. Although various variants of the reaction-diffusion idea have been published over the years, the most commonly used recent models are based on nondispersive reaction rates and nondispersive diffusion. The other class of models is based on the idea that degradation is controlled by first-order reactions with widely distributed (dispersive) reaction rates. We demonstrate that these two classes give fundamentally different predictions for the stochastic degradation and recovery of nanoscale devices, therefore providing the ultimate modeling benchmark. Using detailed experimental time-dependent defect spectroscopy data obtained on such nanoscale devices, we investigate the compatibility of these models with experiment. Our results show that the diffusion of hydrogen (or any other species) is unlikely to be the limiting aspect that determines degradation. On the other hand, the data are fully consistent with reaction-limited models. We finally argue that only the correct understanding of the physical mechanisms leading to the significant device-to-device variation observed in the degradation in nanoscale devices will enable accurate reliability projections and device optimization.
关键词： NBTI,dispersive reaction rates,first-order processes,PBTI,Bias temperature instability,reaction-diffusion,oxide defects,charge trapping
更新于2025-09-19 17:13:59
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Afterglow Effects as a Tool to Screen Emissive Non-Geminate Charge Recombination Processes in Organic Photovoltaic Composites
摘要： Disentangling temporally-overlapping charge carrier recombination events in organic bulk heterojunctions by optical spectroscopy is challenging. Here, a new methodology for employing delayed luminescence spectroscopy is presented. The proposed method is capable of distinguishing between recombination of spatially-separated charge carriers and trap-assisted charge recombination simply by monitoring the delayed luminescence (afterglow) of bulk heterojunctions with a quasi time-integrated detection scheme. Applied on the model composite of the donor poly(6,12-dihydro-6,6,12,12-tetraoctyl-indeno[1,2-b]fluorene-alt-benzothiadiazole) (PIF8BT) polymer and the acceptor ethyl-propyl perylene diimide (PDI) derivative, i.e. PIF8BT:PDI, the luminescence of charge-transfer (CT) states created by non-geminate charge recombination on the ns – μs time scale is observed. Fluence-dependent, quasi time-integrated detection of the CT luminescence monitors exclusively emissive charge recombination events, while rejecting the contribution of other early-time emissive processes. Trap-assisted and bimolecular charge recombination channels are identified based on their distinct dependence on fluence. The importance of the two recombination channels is correlated with the layer’s order and electrical properties of the corresponding devices. Four different microstructures of the PIF8BT:PDI composite obtained by thermal annealing are investigated. Thermal annealing of PIF8BT:PDI shrinks the PDI domains in parallel with the growth of the PIF8BT domains in the blend. Common to all states studied, the delayed CT luminescence signal is dominated by trap-assisted recombination. Yet, the minor fraction of fully-separated charge recombination in the overall CT emission increases as the difference in the size of the donor and acceptor domains in the PIF8BT:PDI blend becomes larger. Electric field-induced quenching measurements on complete PIF8BT:PDI devices confirm quantitatively the dominance of emissive trap-limited charge recombination and demonstrate that only 40% of the PIF8BT/PDI CT luminescence comes from the recombination of fully-separated charges, taking place within 200 ns after photoexcitation. The method is applicable to other non-fullerene acceptor blends beyond the system discussed here, if their CT state luminescence can be monitored.
关键词： multiple-diode equivalent circuit,fill factor,solar cell,charge trapping,perylene diimides,non-fullerene acceptors,delayed luminescence,photodetector
更新于2025-09-12 10:27:22
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MXene Quantum Dot/Polymer Hybrid Structures with Tunable Electrical Conductance and Resistive Switching for Nonvolatile Memory Devices
摘要： Low-dimensional MXene materials including MXene quantum dots (MQDs) and nanosheets have attracted extensive attention owing to their unique structures and novel properties, but their most attractive features are still less explored than expected. A systematic study of the memory effects of MQD-based electronics is reported. Monodisperse MQDs are prepared by using a one-step facile hydrothermal synthetic method. By varying the MQD content in polyvinylpyrrolidone (PVP) hybrid composite films, the electrical conductance of an indium tin oxide (ITO)/MQD-PVP/gold (Au) sandwich structure can be tuned precisely from insulator behavior to irreversible resistive switching, reversible resistive switching, and conductor behavior. These irreversible and reversible resistive switches are capable of exhibiting write-once-read-many times (WORM) and flash memory effects, respectively. Both types of devices operate stably under retention testing, with a high on/off current ratio up to 100. The tunable memory and transient features of these hybrid films are likely due to MQD charge trapping due to their quantum confinement and dissolvability of memristive components. The results suggest that MXene nanomaterials are promising as resistive switching trigger for emerging nonvolatile memories for data storage, specially data storage security.
关键词： resistive switching,MXene quantum dots,charge trapping,flash memory,nonvolatile memory,write-once-read-many memory
更新于2025-09-12 10:27:22
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Influence of Work Function of Carrier Transport Materials with Perovskite on Switchable Photovoltaic Phenomena
摘要： The hysteresis effect and switchable photovoltaic phenomena in organo-metal halide perovskite have been observed in perovskite solar cells with certain structures and under certain measure conditions. These phenomena were favorably applied to resistive random-access memory and human-brain-mimicking devices, especially using photons as a reading or stress probe apart from using electrical probe. However, the mechanisms causing these effects are not fully understood. In this paper, the perovskite devices with different hole transporting layers, which have the work functions ranging from 5.9 eV to 3.7 eV, were fabricated and systematically characterized by current-voltage measurements and time-resolved photo-response measurements. These measurements show that the switchable photovoltaic phenomena are highly related to the work function of the hole transporting layer. The interfacial electronic structures of perovskite and several materials were studied in details using X-ray and ultraviolet photoemission spectroscopy (XPS and UPS), suggesting that the switchable photovoltaic is extensively dependent on the strong band bending effect. Light-mediated XPS measurements reveals that the degree of band bending in the perovskite layer was manipulated by charge trapping/de-trapping and hole-carrier accumulation. Based on the electrical measurements and band diagram, we propose a model that combines ion migration and charge trapping/detrapping processes to explain the switchable photovoltaic phenomena.
关键词： work function,band bending,hole transporting layer,perovskite,ion migration,charge trapping,switchable photovoltaic
更新于2025-09-11 14:15:04
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Numerical simulation on the surface charge accumulation process of epoxy insulator under needle-plane corona discharge in air
摘要： Most of the HV power equipment with gas–solid insulation suffers a lot from the surface charge accumulation due to corona discharge. The existence of surface charge distorts the local electric field and leads to surface flashover faults in extreme situations. As a result, it is important to figure out the mechanism of surface charge accumulation process. In this study, a simulation model combining both the plasma hydrodynamics and charge trapping–detrapping process was built. The simulation results have a good agreement with the experimental data, the main summary is as follows: in the surface charge accumulation process, the corona discharge intensity increases first and then decreases with time. The curves of the surface potential distributions have different shapes at different times, the central value goes up rapidly with time in the beginning and finally reaches saturation. Surface charges exist in the skin layer of epoxy insulator, some of them may be captured by traps while transporting away under built-in electric field.
关键词： corona discharge,charge trapping–detrapping process,plasma hydrodynamics,epoxy insulator,surface charge accumulation
更新于2025-09-10 09:29:36