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1.
    
Ferroelectrics are multifunctional materials that reversibly change their polarization under an electric field. Recently, the search for new ferroelectrics has focused on organic and bio‐organic materials, where polarization switching is used to record/retrieve information in the form of ferroelectric domains. This progress has opened a new avenue for data storage, molecular recognition, and new self‐assembly routes. Crystalline glycine is the simplest amino acid and is widely used by living organisms to build proteins. Here, it is reported for the first time that γ‐glycine, which has been known to be piezoelectric since 1954, is also a ferroelectric, as evidenced by local electromechanical measurements and by the existence of as‐grown and switchable ferroelectric domains in microcrystals grown from the solution. The experimental results are rationalized by molecular simulations that establish that the polarization vector in γ‐glycine can be switched on the nanoscale level, opening a pathway to novel classes of bioelectronic logic and memory devices.  相似文献   

2.
    
Volatile threshold switching (TS) and non‐volatile memory switching (MS) are two typical resistive switching (RS) phenomena in oxides, which could form the basis for memory, analog circuits, and neuromorphic applications. Interestingly, TS and MS can be coexistent and converted in a single device under the suitable external excitation. However, the origin of the transition from TS to MS is still unclear due to the lack of direct experimental evidence. Here, conversion between TS and MS induced by conductive filament (CF) morphology in Ag/SiO2/Pt device is directly observed using scanning electron microscopy and high‐resolution transmission electron microscopy. The MS mechanism is related to the formation and dissolution of CF consisting of continuous Ag nanocrystals. The TS originates from discontinuous CF with isolated Ag nanocrystals. The results of current–voltage fitting and Kelvin probe force microscopy further indicate that the TS mechanism is related to the modulation of the tunneling barrier between Ag nanocrystals in CF. This work provides clearly experimental evidence to deepen understanding of the mechanism for RS in oxide‐electrolyte‐based resistive switching memory, contributing to better control of the two RS behaviors to establish high‐performance emerging devices.  相似文献   

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4.
    
Mechanical flexibility and electrical reliability establish the fundamental criteria for wearable and implantable electronic devices. In order to receive intrinsically stretchable resistive switching memories, both the electrode and storage media should be flexible yet retain stable electrical properties. Experimental results and finite element analysis reveal that the formation of 3D liquid metal galinstan (GaInSn) calabash bunch conductive network in poly(dimethyl siloxane) (PDMS) matrix allows GaInSn@PDMS composite as soft electrode with the stable conductivity of >1.3 × 103 S cm−1 at the stretching strains of >80% and a fracture strain extreme of 108.14%, while the third‐generation metal–organic framework MIL‐53 thin film with a facial rhombohedral topology enables large mechanical deformation up to a theoretical level of 17.7%. Combining the use of liquid metal–based electrode and MIL‐53 switching layer, for the first time, intrinsically stretchable RRAM device Ag/MIL‐53/GaInSn@PDMS is demonstrated that can exhibit reliable resistive switching characteristics at the strain level of 10%. The formation of fluidic gallium conductive filaments, together with the structural flexibility of the GaInSn@PDMS soft electrode and MIL‐53 insulating layer, accounts for the uniform resistive switching under stretching deformation scenario.  相似文献   

5.
    
Developing a means by which to compete with commonly used Si‐based memory devices represents an important challenge for the realization of future three‐dimensionally stacked crossbar‐array memory devices with multifunctionality. Therefore, oxide‐based resistance switching memory (ReRAM), with its associated phenomena of oxygen ion drifts under a bias, is becoming increasingly important for use in nanoscalable crossbar arrays with an ideal memory cell size due to its simple metal–insulator–metal structure and low switching current of 10–100 μA. However, in a crossbar array geometry, one single memory element defined by the cross‐point of word and bit lines is highly susceptible to unintended leakage current due to parasitic paths around neighboring cells when no selective devices such as diodes or transistors are used. Therefore, the effective complementary resistive switching (CRS) features in all Ti‐oxide‐based triple layered homo Pt/TiOx/TiOy/TiOx/Pt and hetero Pt/TiOx/TiON/TiOx/Pt geometries as alternative resistive switching matrices are reported. The possible resistive switching nature of the novel triple matrices is also discussed together with their electrical and structural properties. The ability to eliminate both an external resistor for efficient CRS operation and a metallic Pt middle electrode for further cost‐effective scalability will accelerate progress toward the realization of cross‐bar ReRAM in this framework.  相似文献   

6.
    
High‐performance memristors based on AlN films have been demonstrated, which exhibit ultrafast ON/OFF switching times (≈85 ps for microdevices with waveguide) and relatively low switching current (≈15 μA for 50 nm devices). Physical characterizations are carried out to understand the device switching mechanism, and rationalize speed and energy performance. The formation of an Al‐rich conduction channel through the AlN layer is revealed. The motion of positively charged nitrogen vacancies is likely responsible for the observed switching.  相似文献   

7.
    
Resistive switching devices herald a transformative technology for memory and computation, offering considerable advantages in performance and energy efficiency. Here, a simple and scalable material system of conductive oxide interfaces is employed, and their unique properties are leveraged for a new type of resistive switching device. An Al2O3–TiO2-based valence-change resistive switching device, where the conductive oxide interface serves both as the bottom electrode and as a reservoir of defects for switching, is demonstrated. The amorphous–polycrystalline Al2O3–TiO2 conductive interface is obtained following the technological path of simplifying the fabrication of the 2D electron gases (2DEGs), making them scalable for practical mass integration. Physical analysis of the device chemistry and microstructure with comprehensive electrical analysis of its switching behavior and performance is combined. The origin of the resistive switching is pinpointed to the conductive oxide interface, which serves both as the bottom electrode and as a reservoir of oxygen vacancies. The latter plays a key role in valence-change resistive switching devices. The new device, based on scalable and complementary metal–oxide–semiconductor (CMOS)-technology-compatible fabrication processes, opens new design spaces toward increased tunability and simplification of the device selection challenge.  相似文献   

8.
    
Crossbar‐type bipolar resistive memory devices based on low‐temperature amorphous TiO2 (a‐TiO2) thin films are very promising devices for flexible nonvolatile memory applications. However, stable bipolar resistive switching from amorphous TiO2 thin films has only been achieved for Al metal electrodes that can have severe problems like electromigration and breakdown in real applications and can be a limiting factor for novel applications like transparent electronics. Here, amorphous TiO2‐based resistive random access memory devices are presented that universally work for any configuration of metal electrodes via engineering the top and bottom interface domains. Both by inserting an ultrathin metal layer in the top interface region and by incorporating a thin blocking layer in the bottom interface, more enhanced resistance switching and superior endurance performance can be realized. Using high‐resolution transmission electron microscopy, point energy dispersive spectroscopy, and energy‐filtering transmission electron microscopy, it is demonstrated that the stable bipolar resistive switching in metal/a‐TiO2/metal RRAM devices is attributed to both interface domains: the top interface domain with mobile oxygen ions and the bottom interface domain for its protection against an electrical breakdown.  相似文献   

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10.
    
This study demonstrates a synergistic approach of dual nanostructure engineering to improve the performance of AlOx‐based resistive random access memory (RRAM) devices. More precisely, a novel material stack engineering of RRAM with nonlinear area scalable low current switching and extensive improvement of reliability and variability issues is reported. Dual nanostructures (nanodome bottom electrode and nanocrystals in switching layer) in RRAM is an effective way to change the switching from filamentary to a nonfilamentary one, resulting in forming‐free highly stable device. Several methods such as transmission electron microscopy, energy dispersive spectroscopy, and atomic force microscopy have been employed to investigate the morphology of the RRAM devices. Enhanced electric field within the enclave of switching layer is controlling the intrinsic distribution of oxygen vacancy profile with extrinsic operation. As compare to filamentary RRAM, nonfilamentary devices can effectively control dc switching for >103 cycles, ac switching for >106 cycles without any severe fluctuation of resistance states for different levels. Area and temperature‐dependent semiconducting behavior along with time‐dependent high resistance states are certainly confirming the nonfilamentary switching process. In addition, the device yield improvement ≈98% using nonfilamentary switching, is making dual nanostructure devices a very promising candidate for high‐density memory application, is highlighted.  相似文献   

11.
    
High‐performance polymer memory is fabricated using blends of ferroelectric poly(vinylidene‐fluoride‐trifluoroethylene) (P(VDF‐TrFE)) and highly insulating poly(p‐phenylene oxide) (PPO). The blend films spontaneously phase separate into amorphous PPO nanospheres embedded in a semicrystalline P(VDF‐TrFE) matrix. Using low molecular weight PPO with high miscibility in a common solvent, i.e., methyl ethyl ketone, blend films are spin cast with extremely low roughness (Rrms ≈ 4.92 nm) and achieve nanoscale phase seperation (PPO domain size < 200 nm). These blend devices display highly improved ferroelectric and dielectric performance with low dielectric losses (<0.2 up to 1 MHz), enhanced thermal stability (up to ≈353 K), excellent fatigue endurance (80% retention after 106 cycles at 1 KHz) and high dielectric breakdown fields (≈360 MV/m).  相似文献   

12.
    
This study investigates the electrical behavior of a hybrid memory device with both memory and selector characteristics. Electrical measurements and simulations indicate that the electrical behaviors (nonvolatile characteristics in Al2O3 layers and volatile characteristics in TiO2 layers) are linked to the stability of the conductive filament (CF) used. The binding energy between the Ag atoms in the CF is crucial for achieving nonvolatile or volatile characteristics. Thus, the hybrid memory device exhibits tunable threshold-voltage characteristics and a consistent off-state without requiring an additional selector device. Furthermore, the buffer metal layer between the active electrode and oxide layer affects the filament-formation process in terms of the switching time. Experimental results show that the buffer layer significantly affects ion motion, such as redox reactions and ion migration. Thus, hybrid memory devices with a Zr buffer layer can solve the voltage–time dilemma, enabling fast and low-voltage switching. Robust XNOR-based neural network applications are developed using hybrid memory devices in a cross-point array with characteristics such as scalability, simple structure, and excellent switching characteristics. By carefully considering the on–off ratio and device variability, hybrid memory devices can ensure reliable operation with a high pattern recognition accuracy in XNOR-based neural neuromorphic hardware systems.  相似文献   

13.
    
Light‐tunable resistive switching (RS) characteristics are demonstrated in a photochromophore (BMThCE)‐based resistive random access memory. Triggered by nondestructive ultraviolet or visible light irradiation, two memory‐type RS characteristics can be reversibly modulated in the same device upon a narrow range of applied voltage (<6 V), accompanied by the photochromophores in the active layer reversibly changed between ring‐open state (namely, o ‐BMThCE) and ring‐closed state (namely, c ‐BMThCE). The o ‐BMThCE‐based memory exhibits a write‐once‐read‐many characteristic with a high current on/off ratio of 105, while the c ‐BMThCE‐based one shows a flash characteristic. Both of the RS characteristics present good nonvolatile stability with the resistance states maintained over 104 s without variation. This RS modulation is possibly related to the formation and rupture of conductive filaments, which formed along channels consisting of BMThCE trapping molecules. This work provides a new memory element for the design of light‐controllable high density storage and data encryption technology.  相似文献   

14.
    
Composite films consisting of fluorinated graphene flakes with vanadium oxide (V2O5) nanoparticles exhibit a stable bipolar resistive switching effect that depends on the size of the composite particles, on the proportion between the film components, on the heat‐treatment conditions of the films (or on the hydration degree of V2O5 nanoparticles), and on the area of the structures. The ON/OFF current ratio of printed crossbar structures reaches 106–109 for films 20–50 nm thick, with the switching voltage varying in the range from 1.5 to 3.7 V, 30 ns time for structure switching, and endurance characteristics up to 1.3 × 103 switching cycles without any changes in ON/OFF current ratio. A mechanism to describe the resistive switching effect implying the formation of sign‐alternating electric fields in a multibarrier structure is proposed. The investigated structures are of interest for the fabrication of nonvolatile memory cells, including memory cells for flexible and printed electronics.  相似文献   

15.
    
Organic resistive memory devices are one of the promising next‐generation data storage technologies which can potentially enable low‐cost printable and flexible memory devices. Despite a substantial development of the field, the mechanism of the resistive switching phenomenon in organic resistive memory devices has not been clearly understood. Here, the time–dependent current behavior of unipolar organic resistive memory devices under a constant voltage stress to investigate the turn‐on process is studied. The turn‐on process is discovered to occur probabilistically through a series of abrupt increases in the current, each of which can be associated with new conducting paths formation. The measured turn‐on time values can be collectively described with the Weibull distribution which reveals the properties of the percolated conducting paths. Both the shape of the network and the current path formation rate are significantly affected by the stress voltage. A general probabilistic nature of the percolated conducting path formation during the turn‐on process is demonstrated among unipolar memory devices made of various materials. The results of this study are also highly relevant for practical operations of the resistive memory devices since the guidelines for time‐widths and magnitudes of voltage pulses required for writing and reading operation can be potentially set.  相似文献   

16.
    
Nonvolatile optoelectronic memories integrated with the functions of sensing, data storage, and data processing are promising for the potential Internet of things (IoT) applications. To meet the requirements of IoT devices, multifunctional memory devices with low power consumption and secure data storage are highly desirable. This study demonstrates an optoelectronic resistive switching memory integrated with sensing and logic operations by adopting organic–inorganic hybrid CH3NH3PbI3?xClx perovskites, which possess unusual defect physics and excellent light absorption. The CH3NH3PbI3?xClx cell exhibits low operation voltage of 0.1 V with the assistance of light illumination, long‐term retention property, and multiple resistance states. Its unique optoelectronic characteristics enable to perform logic operation for inputting one electrical pulse and one optical signal, and detect the coincidence of electrical and optical signal as well. This design provides possibilities for smart sensor in IoT application.  相似文献   

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18.
    
The resistive random access memory (RRAM) device has been widely studied due to its excellent memory characteristics and great application potential in different fields. In this paper, resistive switching materials, switching mechanism, and memory characteristics of RRAM are discussed. Recent research progress of RRAM in high-density storage and nonvolatile logic application are addressed. Technological trends are also discussed.  相似文献   

19.
    
Coexistence of negative differential resistance (NDR) and resistive switching (RS) memory is observed using a Ag|TiOx|F‐doped‐SnO2 memory cell at room temperature. Unlike other reports, the coexistence of NDR and RS strongly depends on the relative humidity levels at room temperature. The NDR disappears when the cells are placed in a dry air ambient (H2O < 5 ppm) or in vacuum, but the coexistence emerges and gradually becomes obvious after the cells are exposed to ambient air with relative humidity of 35%, and then becomes dramatically enhanced as the relative humidity becomes higher. Due to the excellent stability and reversibility of the coexistence of NDR and RS, a multilevel RS memory is developed at room temperature. Hydroxide ion (OH−) is induced by gas‐phase water‐molecule splitting on the surface and interface of the memory cell. The OH− interacts with oxygen vacancies and transports in the bulk of memory cell to facilitate the migration of Ag ions and oxygen vacancies along grain boundaries. These processes are responsible for the moisture‐modulated and room‐temperature coexistence. This work demonstrates moisture‐modulated coexistence of NDR and RS for the first time and gives an insight into the influence of water molecules on transition‐metal‐oxide‐based RS memory systems.  相似文献   

20.
    
Electronic devices with simultaneous manifestation of multiphysical properties are of great interest due to their possible application in multifunctional devices. In the present study, simultaneous execution of negative differential resistance (NDR) effect, current rectification (≈105), and resistive switching characteristics (≈103) are demonstrated in BaTiO3/CeO2 heterostructure. Although the negative differential effect has gained huge attention, its instability and poor reproducibility at room temperature are the main obstacles to its possible application in electronic devices. However, in this report, the NDR is observed even after hundreds of cycles in BaTiO3/CeO2 heterostructure at 300 K. For a detailed analysis of the NDR effect, AC conductance spectroscopy is performed, which reveals that the presence of NDR is associated with trapping/detrapping of charge carriers at interface states formed at the BaTiO3/CeO2 interface. In addition, the resistive switching and rectification effect are demonstrated due to a barrier at the BaTiO3/CeO2 interface, which can be strongly modulated by thickness (20, 50, and 80 nm) based ferroelectric polarization of BaTiO3. However, the results show that the remarkable performance of these devices makes them a potential candidate for application in multifunctional devices.  相似文献   

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