Promise For Electronic Devices Research Articles

An Encapsulation-Free and Hierarchical Porous Triboelectric Scaffold with Dynamic Hydrophilicity for Efficient Cartilage Regeneration.

Tissue engineering and electrotherapy are two promising methods to promote tissue repair. However, their integration remains an underexplored area, because their requirements on devices are usually distinct. Triboelectric nanogenerators (TENGs) have shown great potential to develop self-powered devices. However, due to their susceptibility to moisture, TENGs have to be encapsulated in vivo. Therefore, existing TENGs cannot be employed as tissue engineering scaffolds, which require direct interaction with surrounding cells. Here, the concept of triboelectric scaffolds (TESs) is proposed. Poly(glycerol sebacate), a biodegradable and relatively hydrophobic elastomer, is selected as the matrix of TESs. Each hydrophobic micropore in multi-hierarchical porous TESs efficiently serves as a moisture-resistant working unit of TENGs. Integration of tons of micropores ensures the electrotherapy ability of TESs in vivo without encapsulation. Originally hydrophobic TESs are degraded by surface erosion and transformed into hydrophilic surfaces, facilitating their role as tissue engineering scaffolds. Notably, TESs seeded with chondrocytes obtain dense and large matured cartilages after subcutaneous implantation in nude mice. Importantly, rabbits with osteochondral defects receiving TES implantation show favorable hyaline cartilage regeneration and complete cartilage healing. This work provides a promising electronic biomedical device and will inspire a series of new in vivo applications.

Nonvolatile behavior of resistive switching memory in Ag/WOx/TiOy/ITO device based on WOx/TiOy heterojunction

Two-terminal structure memristors are the most promising electronic devices that could play a significant role in artificial intelligence applications of the next generation and the post-Moore era. In this work, we fabricated the memristive device by depositing a heterojunction WOx/TiOy functional layer onto an indium tin oxide substrate using magnetron sputtering. The Ag/WOx/TiOy/ITO device exhibits improved memory behavior of bipolar resistive switching (RS) nonvolatile compared to TiOy-based single-layer memristors, enabling it to meet high-density information storage requirements. Moreover, our device exhibited the coexistence of the negative differential resistance effect and the behavior of the RS memory. Through a comprehensive analysis of conductivity on the curve of current–voltage (I–V), a physical model based on the mechanism of space charge-limited current, ohmic conduction, and Schottky emission was suggested to explain the behavior device RS memory. This study's findings demonstrate that including a heterojunction bilayer WOx/TiOy as a functional layer can significantly improve the performance of memristive devices. This advancement expands the potential application of ferroelectric metallic oxide heterojunctions within the field of memristors.

Spectroscopic and electrical properties of polymer nanocomposite films based on PMMA/PVDF incorporated with silicon oxide (SiO2) for promising electronic devices

Spectroscopic and electrical properties of polymer nanocomposite films based on PMMA/PVDF incorporated with silicon oxide (SiO2) for promising electronic devices

Resurrected and Tunable Conductivity and Ferromagnetism in the Secondary Growth La0.7Ca0.3MnO3 on Transferred SrTiO3 Membranes.

To avoid the epitaxy dilemma in various thin films, such as complex oxide, silicon, organic, metal/alloy, etc., their stacking at an atomic level and secondary growth are highly desired to maximize the functionality of a promising electronic device. The ceramic nature of complex oxides and the demand for accurate and long-range-ordered stoichiometry face severe challenges. Here, the transport and magnetic properties of the La0.7Ca0.3MnO3 (LCMO) secondary growth on single-crystal freestanding SrTiO3 (STO) membranes are demonstrated. It has been experimentally found that on an only 10 nm thick STO membrane, the LCMO can offer a bulk-like Curie temperature (TC) of 253 K and negative magnetoresistance of -64%, with a weak dependence on the thickness. The resurrected conductivity and ferromagnetism in LCMO confirm the advantages of secondary growth, which benefits from the excellent flexibility and transferability. Additionally, this study explores the integration strategy of complex oxides with other functional materials.

Memristors Constructed by CsPbIBr2 Inorganic Halide Perovskite for Artificial Synapse and Logic Operation

Neuromorphic devices are one of the promising electronic devices that are implementing artificial neural networks and substituting for traditional semiconductor devices in recent years. Inorganic halide perovskite (IMHP) is considered as an advantageous material to constitute neuromorphic components. Herein, the CsPbIBr2 memristor displays superior resistive‐switching properties under various temperature and storage periods. In addition, synaptic plasticity, including paired pulse facilitation and spiking timing‐dependent plasticity, is observed for CsPbIBr2 device, whose resistance manipulation is also established in both DC and pulse modes. Moreover, the decimal operation function of numbers by applying pulse stimulation to the device to regulate the device conductance is realized. This work demonstrates the feasibility of IMHP in neuromorphic devices, accelerating the application of neuromorphic computing.

Stretchable helical fibers with skin-core structure for pressure and proximity sensing

As a multifunctional monitoring platform based on the human environment, fiber-based capacitive sensors are promising wearable electronic devices. However, it is of great challenge to select suitable dielectric materials and construct a bimodal capacitive sensor with excellent stretchability, high compatibility and stable sensing capability. Here, we report a bacterial cellulose (BC)@BC/carbon nanotube (CNT) helical fiber with skin-core structure, and biodegradable BC as the skin and conductive BC/CNT as the core, which exhibits tensile strength of 148 MPa and break elongation of 536 %. Two helical fibers are cross-assembled into a bimodal sensor, dedicated to detecting pressure and proximity. In the contact mode, the capacitance of the sensor increases with the increase of the pressure (0–50 N) with good sensitivity of 2.92 N−1. In the noncontact mode, the sensor exhibits a monitoring range of 0–20 cm, and the capacitance change rate is 31 % when the finger is close to 0.5 cm. Additionally, our bimodal sensor can be used to detect the body’s omnidirectional motion and even help referees to efficient judgment in sports. In a word, our capacitive sensor provides a tremendous advantage and foundation for the development of smart fibers and the research of intelligent textiles.

Effect of Proton Irradiation Fluence on the Linearity and Symmetry of Conductance Tuning of a HfO x /TiO x Heterojunction-Based Memristor

Binary metal oxide memristor-based artificial neural synapses offer the advantages of high-density information storage, high-efficiency computing, low power consumption and strong antiradiation damage and are therefore promising aerospace electronic devices. However, the unclear damage trends and mechanisms causing nonlinearity and asymmetry during conductance tuning under irradiation have restricted further development. Here, the damage trends and mechanisms caused by proton irradiation in Au/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> /Ti memristors were studied. Results show that when the fluence of proton (25 MeV) irradiation increases to 2×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> p/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , the Au/HfO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> /TiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><i>x</i></sub> /Ti memristor cannot return to its original high-resistance state upon conductance reduction, making the conductance tuning less linear and symmetric. X-ray photoelectron spectroscopy analysis revealed that the mechanism underlying the decrease in the linearity and symmetry of the conductance tuning is proton irradiation increasing oxygen vacancies in the heterojunction. These results can guide better design of metal oxide memristive devices suitable for aerospace devices and better modeling of devices with nonideal properties under irradiation.

Thermal Conductivity of a Two-Dimensional Diamondene Sheet: A Molecular Study

Diamondene, as a novel two-dimensional layered material, exhibits a high carrier mobility resembling those of diamond thin films and holds great promise in electronic devices, while its thermal properties are yet to be investigated. In this paper, the thermal behaviors of diamondene are investigated using molecular dynamic simulation, and the effects of orientation, temperature, hydrogenation, and defect on the thermal conductivity are considered. At simulated temperatures of 300 K, for diamondene, the thermal conductivities of the armchair direction consist of with that of the zigzag direction. The thermal conductivity of quantum correction is reduced to 89% of the classical MD results. The thermal conductivity is sensitive to strain engineering but almost independent of surface chemical functionalization. Thermal conductivity decreases with defect concentration and then enhances (stable stage at a defect concentration range of 20 and 80%). The phenomena are explained by phonon-density-state and micro-heat-flux scatting. It is attributed to the interplay between two cooperating/competing mechanisms of phonon and the compressive effect of the scatted phonon at different chirality. Our study offers a fundamental understanding of thermal transport in diamondene, which will enrich the studies of 2D materials in the field of thermal transfer.

Perspectives of spin-valley locking devices

Valleytronics is an emerging field of research which utilizes the valley degree of freedom to encode information. However, it is technically nontrivial to produce a stable valley polarization and to achieve efficient control and manipulation of valleys. Spin–valley locking refers to the coupling between spin and valley degrees of freedom in the materials with large spin–orbit coupling (SOC) and enables the manipulation of valleys indirectly through controlling spins. Here, we review the recent advances in spin–valley locking physics and outline possible device implications. In particular, we focus on the spin–valley locking induced by SOC and external electric field in certain two-dimensional materials with inversion symmetry and demonstrate the intriguing switchable valley–spin polarization, which can be utilized to design the promising electronic devices, namely, valley-spin valves and logic gates.

Exploring conductance modulation and implementation of convolutional neural network in Pt/ZnO/Al2O3/TaN memristors for brain-inspired computing

Oxide-based memristors have emerged as a promising electronic device for high-density memory and neuromorphic applications. In our study, we explored the tunable analog switching and biological synaptic functions of a Pt/ZnO/Al2O3/TaN memristive device. Using transmission electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS), we confirmed the presence of a TaOxNy interface layer at the anode contact, believed to play a critical role in resistance transitions. The memristive device showed excellent performance, including a stable and reproducible analog switching memory with a low operating voltage (μ=̶2.0/+1.7V), good cycling endurance (2 × 102), a high on/off ratio (>103), and retention up to 104 s at 85 °C. Additionally, multi-state resistances were achieved by varying the reset voltage, enabling the creation of neuromorphic synapses and high-density memories. Direct-current mode set and reset transitions showed multi-state resistance changes similar to potentiation and depression behaviors in biological synapses. Further simulations, including long-term potentiation (LTP) and long-term depression (LTD), paired pulse facilitation (PPF), and convolutional neural network (CNN) simulations for handwritten digits, showed an accuracy of 86.5%. These results indicate that the memristive device is highly suitable for use in high-density memory and brain-inspired computer systems.

Nonvolatile resistive switching memory behavior in WOx/BiFeOy heterojunction based memristor

Memristors with a two-terminal structure are considered to be one of the most promising electronic devices capable of overcoming the Von Neumann bottleneck, which is highly anticipated in the post-Moore era and next-generation artificial intelligence applications. In this work, a memristive device was fabricated using a WOx/BiFeOy heterojunction as functional layer on F-doped SnO2 (FTO) substrate by magnetron sputtering. The Ag/WOx/BiFeOy/FTO device exhibits enhanced bipolar nonvolatile resistive switching (RS) memory behavior compared with single-layer BiFeOy-based memristors, which can meet the requirements of high-density information storage. By performing a comprehensive conductivity analysis on the current-voltage (I-V) curve, it was proposed a reasonable physical model to explain the RS memory behavior of the device based on space-charge-limited current (SCLC) mechanism and the Schottky emission. Therefore, this work indicates that the bilayer WOx/BiFeOy heterojunction as functional layer can effectively improve the performance of memristive devices, which will further expand the application of ferroelectric/metal oxide heterojunction in the field of memristors.

Synthesis of high-purity and high-crystallinity single-walled carbon nanotubes homogeneously dispersed by wet process

• The highly crystalline single-walled carbon nanotubes are basic electronic elements. • It is necessary to remove contaminants in hc-SWCNTs to disperse them homogeneously. • Carbon contaminants in hc-SWCNTs disperse the shear force of hc-SWCNT bundles. • The shear force to disperse hc-SWCNTs is required to break up their aggregates. • Highly purified hc-SWCNTs could be dispersed without deteriorated chemical stability. Field emission (FE) electron sources based on high-purity and high-crystallinity single-walled carbon nanotubes (hc-SWCNTs) are promising electronic devices from the viewpoint of industrial application. However, to utilize high-purity hc-SWCNTs as a component of electronic devices, it is necessary to homogeneously disperse hc-SWCNTs using a wet process. Shear force is required to break up aggregates of hc-SWCNTs to produce a film with uniformly dispersed hc-SWCNTs, but contaminants such as fine graphite in the aggregates disperse the shear force of hc-SWCNT bundles. Therefore, it is necessary to remove these contaminants to achieve the uniform dispersion of hc-SWCNTs. In this study, we have succeeded in the highly efficient synthesis of hc-SWCNTs with few contaminants by the arc discharge method using glass-like carbon as a raw material to produce SWCNTs. It was demonstrated that hc-SWCNTs with low foreign matter contamination can be uniformly dispersed without the need for wet dispersion tools such as a homogenizer and a jet mill. Moreover, the long-term stability of the current emitted by FE devices fabricated using the dispersed solution can be obtained.

Transient Response and Firing Behaviors of Memristive Neuron Circuit.

The signal transmission mechanism of the Resistor-Capacitor (RC) circuit is similar to the intracellular and extracellular signal propagating mechanism of the neuron. Thus, the RC circuit can be utilized as the circuit model of the neuron cell membrane. However, resistors are electronic components with the fixed-resistance and have no memory properties. A memristor is a promising neuro-morphological electronic device with nonvolatile, switching, and nonlinear characteristics. First of all, we consider replacing the resistor in the RC neuron circuit with a memristor, which is named the Memristor-Capacitor (MC) circuit, then the MC neuron model is constructed. We compare the charging and discharging processes between the RC and MC neuron circuits. Secondly, two models are compared under the different external stimuli. Finally, the synchronous and asynchronous activities of the RC and MC neuron circuits are performed. Extensive experimental results suggest that the charging and discharging speed of the MC neuron circuit is faster than that of the RC neuron circuit. Given sufficient time and proper external stimuli, the RC and MC neuron circuits can produce the action potentials. The synchronous and asynchronous phenomena in the two neuron circuits reproduce nonlinear dynamic behaviors of the biological neurons.

Pressure evolution of electronic and structural properties in transition metal dichalcogenide 1T-Co1.06Te2

Two-dimensional transition metal dichalcogenides (TMDs) are important materials for promising electronic devices because they usually exhibit excellent and highly tunable electronic properties. Here, we report on the pressure-driven electronic phase transition in a TMD 1T-Co1.06Te2. High-pressure transport measurements reveal a sign reversal of the Hall coefficients at a critical point of P C ∼ 32 GPa, evidencing a transition from hole band(s) dominated transport into one that is dominated by electron band(s). Synchrotron x-ray diffraction experiments demonstrate that no structural phase transition occurs below 46.3 GPa, indicating an electronic origin of the transition. Moreover, a kink anomaly of the lattice constant ratio c/a is also observed at P = P C. These results might indicate a Lifshitz transition which refers to a change of Fermi surface topology in absence of structural transition.

Strain effects on the behavior of intrinsic point defects within the GaN/AlN interface

Defect behaviors in GaN-based compounds studied by using density functional theory have exhibited widely practical applications for optoelectronic devices. Ga is usually used to solubilize in AlN to release the lattice mismatch and the interface strain. In this study, we investigate the formation energies and diffusion barriers of intrinsic point defects within the GaN/AlN interface. The intrinsic defect with the lowest formation energy is positively charged N vacancy, and negatively charged Ga vacancy is the defect with second lower formation energy. Compared with the case in bulk GaN, the GaN/AlN interface promotes the generation of Ga vacancy and inhibits the generation of N vacancy. Meanwhile, the defect diffusion barrier of N vacancy within the GaN/AlN interface is higher than that in the bulk GaN. The hydrostatic compressive/ tensile strain significantly promotes the generation of these two vacancy defects, while biaxial tensile strain and the biaxial compressive strain slightly promote and inhibit the generation of these two vacancy defects, respectively. These interface and strain effects provide the significant information in understanding the electrical properties of GaN-based devices, especially under the extreme conditions. Our work therefore not only elucidates defect behaviors under different strains in GaN/AlN interface, but also paves the way for understanding and designing promising electronic devices with interface engineering.

Ferris-wheel-assisted parylene-C dielectric deposition for improving organic thin-film transistor uniformity

Organic thin film transistor is one of the most promising electronic device technologies for flexible and printed electronics, but device uniformity remains a challenge for large-scale integration circuit design. Despite the advances in semiconductor layers, the quality of dielectric layers is equally important. Parylene-C dielectric has good intrasample thickness uniformity, but demonstrates significant variation among samples fabricated at the same time, thus causing device non-uniformity. In this study, we present a two-dimensional (2D) sample rotation method using a Ferris wheel to improve the thickness uniformity of parylene-C dielectrics. The Ferris wheel averages the deposition rate of parylene-C dielectric on different samples over an identical spherical space, rather than over different horizontal planes by the conventional one-dimensional sample rotation with a rack. The dielectrics fabricated on different cabins of the Ferris wheel demonstrate better thickness uniformity than those fabricated on different floors of the rack, and thus better uniformity of transistors. Specifically, using the 2D rotation Ferris wheel, the coefficient of variation of dielectric thickness is lowered to 0.01 from 0.12 (which uses the conventional rack); the coefficients of variation for the on-state drain current, process transconductance parameter, and threshold voltage of the fabricated transistors are improved to 0.15, 0.16 and 0.08, from 0.33, 0.20 and 0.14, respectively. The improved device uniformity has the potential in complicated flexible circuit design for advanced applications such as edge intelligence.

Revealing progress, challenges, in flexible zinc ion battery design

Study paves a path toward eventual widespread application of promising flexible electronic device energy supply

Phase-controlled epitaxial growth of MoTe2: Approaching high-quality 2D materials for electronic devices with low contact resistance

Because silicon transistors are approaching the limit of device miniaturization, 2D semiconductors show great promise in electronic devices as post-silicon alternatives. However, critical bottlenecks that impede applications remain in 2D material-based devices, such as the lack of scalable fabrication techniques of highly crystalline samples and the challenge of contact resistance. In this Perspective, we review the recently developed 2D MoTe2 as an excellent material in phase-controlled epitaxial growth and phase transition. The high flexibility in phase engineering of MoTe2 enables (1) wafer-scale fabrication of semiconducting MoTe2 single crystals and (2) intrinsically ideal contact geometry for high-performance electronic devices.

Low Power Consumption Gate-Tunable WSe2/SnSe2 van der Waals Tunnel Field-Effect Transistor

Two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted attention as promising next-generation electronic devices and sensors. In this study, we fabricated a novel nanoelectronic device based on a black-phosphorus-gated WSe2/SnSe2 van der Waals (vdW) tunnel field-effect transistor (TFET), where hexagonal boron nitride (h-BN) was used as the gate insulator. We performed morphological, electrical, and optoelectronic characterizations. The p-WSe2/n-SnSe2 heterostructure-based TFET exhibited p-type behavior with a good dependence on the gate voltage. The TFET device showed a trend toward negative differential resistance (NDR) originating from band-to-band tunneling, which can be tuned by applying a gate voltage. The optoelectronic performance of the TFET device was low, with a maximum photoresponsivity of 11 mA W−1, owing to the large device length. The results obtained herein promote the integration of black phosphorus into low-energy-consumption 2D vdW TFETs.

Electrohydrodynamically Printed Flexible Organic Memristor for Leaky Integrate and Fire Neuron

Polymer memristors with good flexibility are promising electronic devices for edge computing paradigms in wearable electronics. However, most reported works present nonvolatile devices, which are suitable for applications in resistive random-access memory or artificial synapse. The volatile devices, which are indispensable in artificial neuron circuits, have rarely been reported, as the resistive switching property of organic devices is usually unstable in volatile devices. Moreover, most reported works use polymers in a way that is not compatible with traditional memristor fabrication technology, which limits the further applications of polymer memristors to large-scale neuromorphic circuits. In this letter, an Ag/Nafion/Au threshold switching memristor was fabricated via electrohydrodynamic printing technology and employed as a core of a leaky integrate and fire neuron circuit. The threshold switching memristor shows excel device size, good endurance, good device-to-device and cycle-to-cycle uniformity, flexibility, and stability at high temperatures. The combination of electrohydrodynamic printing technology and polymer memristor is promising in fast memristor production and largescale edge-computation network circuits.