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We report on the fabrication and the electrical properties of amorphous (α-)InGaZnO4 thin-film transistors deposited on cellulose paper by sputtering at room temperature. The 150-μm-thick paper was used as both a gate dielectric and a substrate for device structural support. The transistors on paper were patterned by lithography and operated in enhancement mode with a threshold voltage of 3.75 V, and exhibited saturation mobility, subthreshold gate-voltage swing, and drain current on-to-off ratio of ∼35 cm2 V-1 s-1, 2.4 V decade-1, and ∼104, respectively. These results verify that simple cellulose paper is a good gate dielectric as well as a low-cost substrate for flexible electronic devices such as paper-based displays. [ABSTRACT FROM AUTHOR]

The cellulose-liquid biphasic dielectric composite serves as the irreplaceable main electrical insulating structure in the power industry, owing to its peculiar high dielectric breakdown strength compared to that of monophasic cellulose paper or insulating liquid. Although this advanced electrical characteristic is utilized worldwide, its physical–chemical nature remains unclear, which greatly restricts the design and improvement of next generation electrical insulating composites. Herein, the interfacial charge behaviors in cellulose-liquid composites are investigated, and the results indicate that the majority of charge carriers in insulating liquid are electrostatically adsorbed at the nano-scale interface, forming interfacial charge traps, leading to 17.66 times increased deep trap density, which suppress further charge migration under high voltages, and consequently lead to the ∼400% improved dielectric breakdown strength compared to that of cellulose paper and insulating liquid. By controlling the interfacial trap characteristics with insulating liquids of strong electron withdrawing ability, the resistivity and breakdown strength of cellulose-liquid composites are further improved. [ABSTRACT FROM AUTHOR]

Flexible organic/inorganic hybrid and proton/electron coupled neuron transistors are self-assembled on paper substrates at room temperature. Solution-processed chitosan-based proton conductor gate dielectrics show a high electric-double-layer specific gate capacitance, which is favorable for low voltage portable application. High performance logic operations are realized on such flexible neuron transistors depending on the operation modes, i.e., 'OR' logic for enhancement-mode device and 'AND' logic for depletion-mode device. Proton/electron interfacial coupling in chitosan-gated neuron transistors is promising for the biological and sensing applications. [ABSTRACT FROM AUTHOR]

A Fabry–Pérot open resonator is a tool dedicated to broadband accurate microwave and mm-wave characterization of dielectric sheets. It has been applied in this paper to the measurement of the dielectric constant and loss tangent of various types of commonly used dielectric materials, such as semiconductors, electronic substrates, glasses, and plastics, in the 20–110 GHz range. The obtained results are in good agreement with the literature data, which are, however, often available only at discrete frequencies, thus making it difficult to recognize dispersive properties of the measured samples. It is shown in this paper that broadband measurement of high-resistivity and intrinsic silicon allows extracting their resistivity solely due to conduction losses. In the case of typical electronic substrates, it is shown that their dielectric constant is almost non-dispersive, whereas losses are, in general, linearly increasing with frequency. Glasses also exhibit almost non-dispersive dielectric constant, which is, however, larger than 3.8, whereas their losses can vary by over two orders of magnitude depending on the properties, like the hydroxyl content. The lowest dielectric constant is easily achievable in common plastics, spanning from ca. 2.03 for Teflon up to ca. 3.0 for PETG. [ABSTRACT FROM AUTHOR]

Optical image edge detection manifests itself as the advantages of fast speed, low energy consumption, parallel operation, and large information capacity, playing a crucial role in object and image recognition in the realms of biology, medicine, and artificial intelligence. In this paper, a dielectric metasurface that can achieve object edge detection in the full visible band is proposed. By combining two optical differential methods referring to spatial spectrum-dependent transmission function and 4f system-based spatial spectrum phase shift, a tetratomic macropixel metasurface that enables polarization-correlated interference based on dual geometric phase modulation is designed, which can achieve object edge detection under 473, 530, and 633 nm wavelengths, and even under white light conditions. This coherent filtering metasurface operator provides a flexible approach for achieving wideband two-dimensional edge detection. [ABSTRACT FROM AUTHOR]

Low-voltage electric-double-layer (EDL) p-channel Mg-doped CuI thin-film-transistors (TFTs) have been fabricated on glass substrates at low temperatures. Electrical properties of the solution-processed CuI TFTs with different Mg doping concentrations were investigated. It is observed that compared to undoped CuI TFTs and Mg0.1Cu0.9Ix TFTs, Mg0.05Cu0.95Ix TFTs exhibit an excellent current on/off ratio of 1.1 × 105, a steep subthreshold swing of 21.78 mV/dec, a higher saturation field-effect mobility of 0.95 cm2 V−1 s−1, and the threshold voltage of 1.81 V. The high specific capacitance of 4.7 μF/cm2 is obtained in solution-processed chitosan dielectrics; when it was used as the gate dielectric instead of traditional SiO2, the operating voltage of TFTs can be reduced to 2.5 V. It is noteworthy that the NAND logic function has been realized on the dual in-plane-gate structure of such Mg0.05Cu0.95Ix-based TFTs. Finally, the effects of laser (λ = 638 nm) and negative bias stress (NBS) were observed on Mg0.05Cu0.95Ix TFTs. The transfer curves of the TFT drifted positively as the power of the laser progressively increased; the OFF-state current gradually increased as the NBS time became longer. This paper provides an effective way to improve the performance of p-channel CuI TFTs and indicates that Mg0.05Cu0.95Ix as a promising p-type material for next-generation high-performance low-power-consumption logic circuit applications. [ABSTRACT FROM AUTHOR]

The separation of Ge and Si by an electrically isolating dielectric layer is essential to yield high efficiency for optical telecommunication applications and electronic applications such as Ge MOSFETs. Ge epitaxial lateral overgrowth (ELOG) is a promising approach to achieve Ge on Si separated by a thin dielectric layer. However, a general understanding of the anisotropic dynamics of ELOG Ge on Si is limited, which prevents its wide adoption. In this paper, we report how the orientation and width of the dielectric layer controls the ELOG. A competitive ELOG from perpendicular directions on a dielectric strip leads to a rapid growth along the long axis of the dielectric layer, or a mixed coalescence from perpendicular directions yielding various Ge confined configurations at the Ge/dielectric-layer interface. Especially, an angle of 7.5° between dielectric-layer and Si [110] axis shows the most pronounced unidirectional ELOG. ELOG disappears as the width of the dielectric mask exceeds 5.0 μm. The results reported here provide a general framework for ELOG of semiconductor materials. [ABSTRACT FROM AUTHOR]

Dielectric patch antenna (DPA) has been extensively studied in recent years, especially for the application of 5G mobile communication system. In this paper, we proposed a notch structure of H-shaped DPA (HDPA) with wideband low-profile properties but without additional components. Temperature stable 0.65 CaTiO3–0.35 LaAlO3 microwave dielectric ceramic of high permittivity was utilized for fabricating the H-shaped dielectric patch, and the method of leveraging the multi-modal features of DPA was introduced. Further analysis of the antenna structure was accomplished by the simplified theoretical method. As a result, the H-shaped notch is properly ensembled in the dielectric patch to make the higher-order TM121 mode close to the dominant TM101 mode, greatly expanding the broadband of the HDPA. The accuracy of the proposed HDPA element model is evaluated by the commercial full-wave simulator CST Microwave Studio. For demonstration, a prototype of the proposed HDPA element operating in the microwave band (5-GHz) has been realized and measured. [ABSTRACT FROM AUTHOR]

In this paper, we extensively characterize and model the threshold voltage instability in lateral β-Ga2O3 MOSFETs with Al2O3 gate dielectric. Specifically, (i) the results indicate that the threshold voltage instability originates from electron trapping at gate dielectric border traps close to the Al2O3/β-Ga2O3 interface. (ii) Logarithmic kinetics were detected for both stress and recovery by means of a innovative fast-capacitance experimental setup, over more than seven decades of time; (iii) a generalized model, which is capable of accurately reproducing the experimental results, was proposed to explain this trend. [ABSTRACT FROM AUTHOR]

This paper presents a hierarchically designed polymer nanocomposite approach in which nanofillers at ultralow volume loading generate large dielectric enhancement in blends of high temperature dielectric polymers with tailored nanostructures. We blend poly(1,4-phenylenen ether sulfone) (PES) with polymers, such as polyetherimide (PEI), that possess more coiled chain conformations to tailor polymer nano-morphologies. Making use of such blends as the matrix, dilute nanocomposites with 0.65 vol. % loading of alumina nanoparticles (20 nm size) generate a marked enhancement in dielectric performance, i.e., raising the dielectric constant K from PES K = 3.9 (and PEI K = 3.2) to the dilute nanocomposites K = 7.6, a much higher enhancement compared with the dilute nanocomposites employing neat polymers as the matrix. The results show that polymer blends with tailored nano-morphologies as the matrix can lead to higher dielectric enhancement in dilute nanocomposites compared with neat polymers as the matrix. [ABSTRACT FROM AUTHOR]

This paper investigates the conditions for a perfect anomalous reflection through a modulated metasurface consisting of a metallic cladding printed over a grounded slab. Differently to what has been previously published, the problem is rigorously addressed by modeling the metallic cladding through an equivalent penetrable impedance and accounting for the grounded slab through the problem's Green's function. It is shown that without polarization transformation, the exact solution exists only for the special case of retroreflection, and, in that case, it can be done simultaneously for the two orthogonal polarizations, with an arbitrary phase shift among the two. On the other hand, changing the polarization of the reflected wave allows one to find an exact solution for arbitrary combinations of incidence and reflection angles. The exact solution is found by imposing that the induced currents radiating with the Green's function of the background problem simultaneously create the desired reflected beam and cancel the specular reflection from the grounded slab. This approach leads to the derivation of a closed-form expression for the homogenized penetrable impedance profile providing perfect anomalous reflection, i.e., ensuring the vanishing of all the coefficients of the waves associated with unwanted diffraction orders, including the specular reflected wave and the evanescent waves. This result is of great practical interest, since the derived penetrable impedance profile can be readily implemented through a simple distribution of metallic patches. The feasibility of this approach is verified through full wave simulations of both the ideal impedance and the patch-based structure, which confirm the effectiveness of the proposed solution. [ABSTRACT FROM AUTHOR]

This paper reports the penetration limit of via holes through dissolving dielectric polymer thin films by inkjet printing. It was found that both the outer diameter of via holes and the polymer thickness affect the penetration depth from the experimental results. Based on this finding, a more accurate relationship between the inner diameter of via holes and the diameter of in-flight droplets for different polymer thicknesses is obtained. [ABSTRACT FROM AUTHOR]

This paper presents an optimal design method for electromagnetic cloaks composed of multiple dielectric materials based on a topology optimization. To obtain optimal configurations that are perfectly free from intermediate materials, so-called grayscales, we apply a Multi-Material Level Set topology description model. The level set functions that are design variables are updated using topological derivatives that also function as design sensitivities, and we derive the topological derivatives for multiple materials. Three numerical examples demonstrate the validity of the proposed method and the advantage of using multiple materials. [ABSTRACT FROM AUTHOR]

By integrating a triboelectric nanogenerator (TENG) and a thin film dielectric elastomer actuator (DEA), the DEA can be directly powered and controlled by the output of the TENG, which demonstrates a self-powered actuation system toward various practical applications in the fields of electronic skin and soft robotics. This paper describes a method to construct a physical model for this integrated TENG-DEA system on the basis of nonequilibrium thermodynamics and electrostatics induction theory. The model can precisely simulate the influences from both the viscoelasticity and current leakage to the output performance of the TENG, which can help us to better understand the interaction between TENG and DEA devices. Accordingly, the established electric field, the deformation strain of the DEA, and the output current from the TENG are systemically analyzed by using this model. A comparison between real measurements and simulation results confirms that the proposed model can predict the dynamic response of the DEA driven by contact-electrification and can also quantitatively analyze the relaxation of the tribo-induced strain due to the leakage behavior. Hence, the proposed model in this work could serve as a guidance for optimizing the devices in the future studies. [ABSTRACT FROM AUTHOR]

Surface dielectric barrier discharges (SDBDs) are a type of asymmetric dielectric barrier discharge (DBD) that can be used to generate ions and produce aerodynamic forces in air. They have shown promise in a range of aerospace applications, including as actuators for solid-state aircraft control or aerodynamic enhancement and as ion sources for electroaerodynamic aircraft propulsion. However, their power draw characteristics are not well understood. Whereas existing approaches use empirical functional fits to estimate the power of specific SDBD configurations, we develop here a physics-based model for SDBD power consumption that accounts for material and geometric variation between SDBDs. The model is based on models for parallel-plate or "volume" DBDs but accounts for the "virtual electrode" resulting from changing plasma length that is particular to SDBDs. We experimentally measure the power of SDBDs of three materials, eleven thicknesses, and 29 electrical operating points to find a correlation with r 2 = 0.99 (n = 106) between model and experiment. We also use SDBD power measurements from four experiments in the literature and find a correlation with r 2 = 0.99 (n = 101) between our model and these experiments. Since we do not use any measured parameters from those experiments in our model, this suggests that our model has the ability to robustly predict the power for different SDBD construction methods and experimental techniques. Therefore, this work provides a robust method for the quantitative design and power optimization of SDBDs for a range of engineering applications, including aerospace propulsion. [ABSTRACT FROM AUTHOR]

This paper presents a triple-wavelength infrared plasmonic thermal emitter using a periodic arrangement of hybrid dielectric materials within a tri-layer metal/dielectric/metal structure. The proposed arrangement makes it possible to sustain multiple resonance of localized surface plasmons (LSP), thereby providing an additional degree of freedom by which to vary the resonant wavelengths in the medium infrared region. Variations in the effective refractive index due to the different modal distribution within dielectric gratings results in multiple LSP resonances, and the resonant wavelengths can be easily tuned by altering the compositions of hybrid dielectric materials. The measured dispersion relation diagram and the finite difference time domain simulation indicated that the resonances were localized. They also indicate that the magnetic fields generated by the multiple LSP modes exhibit distribution patterns similar to that of a standing wave in the periodic arrangement of the hybrid dielectric layer, each of which presents an emission peak corresponding to a different modal order. [ABSTRACT FROM AUTHOR]

An ultra-wideband and high-efficiency polarization rotator based on a metasurface is proposed in this paper. The unit cell of the proposed polarization rotator consists of two pairs of L-shaped metallic patches printed on a substrate, which is backed by a metallic ground and covered by a superstrate. The superstrate is composed of a dielectric layer and a pair of L-shaped metallic patches printed on the dielectric layer. The proposed polarization rotator can rotate the polarization of linearly polarized electromagnetic (EM) wave to its orthogonal counterpart after reflection when the incident EM wave is y-/x-polarized. Simulated results show that the polarization rotator can perform 90° polarization rotation with very high efficiency at seven different frequencies and achieve a polarization conversion ratio higher than 0.9 in the frequency range of 7.8-34.7 GHz at normal incidence. Good agreement between the experimental results and simulated ones has been obtained. [ABSTRACT FROM AUTHOR]

Vortex control is a thriving research area, particularly in relation to flying wing or delta wing aircraft. This paper presents the topological structures of vortex flow on a flying wing aircraft controlled by a nanosecond plasma dielectric barrier discharge actuator. Experiments, including oil flow visualization and two-dimensional particle image velocimetry (PIV), were conducted in a wind tunnel with a Reynolds number of 0.5 x 106. Both oil and PIV results show that the vortex can be controlled. Oil topological structures on the aircraft surface coincide with spatial PIV flow structures. Both indicate vortex convergence and enhancement when the plasma discharge is switched on, leading to a reduced region of separated flow. [ABSTRACT FROM AUTHOR]

This paper reports the investigations of a dielectric filled relativistic magnetron with diffraction output (MDO) on frequency agile. The mechanism of frequency agile is theoretically analyzed. Particle-in-cell simulations and preliminary experiments prove the analytics. In experiments, under the working conditions, 605 kV and 0.3 T, a microwave with 1.98 GHz, 200 MW is radiated from an A6 type MDO when the 95% Al2O3 ceramics with the total thickness of 0.9 cm are filled. Compared with the microwave of 3.72 GHz, 240 MW obtained without the ceramics filled, the frequency agile from S band to L band is achieved. [ABSTRACT FROM AUTHOR]

This paper reports the fabrication of pentacene-based organic thin-film transistors using a dielectric material, Dynasylan ®SIVO110. The devices exhibit excellent performance characterized by a low threshold voltage of-1.4V (operating voltage: 0to-4V) together with a mobility of 1.9 cm² V-1s-1. These results are promising because it uses only a single layer of dielectric without performing any intermediate treatment. The reason is attributed to the high charge storage capacity of the dielectric (κ~20.02), a low interfacial trap density (2.56 × 1011cm-2), and favorable pentacene film morphology consisting of large and interconnected grains having an average size of 234 nm. [ABSTRACT FROM AUTHOR]

Dielectric nanoantennas have generated much interest in recent years owing to their low loss and optically induced electric and magnetic resonances. In this paper, we investigate the coupling between a single emitter and dielectric patch nanoantennas. For the coupled system involving non-spherical structures, analytical Mie theory is no longer applicable. A semi-analytical model is proposed instead to interpret the coupling mechanism and the radiation characteristics of the system. Based on the presented model, we demonstrate that the angular emission of the single emitter can be not only enhanced but also rotated using the dielectric patch nanoantennas. [ABSTRACT FROM AUTHOR]

A dielectric-filled magnetically insulated transmission line oscillator (DFMILO) is presented in this paper, which introduces a low-loss dielectric to fill its resonant cavities and thus improves its technical performances. The fundamental mode frequency of the DFMILO is derived and its dispersion curve is analyzed. In simulation, high-power microwave is generated from the DFMILO with peak power of 3.1 GW, frequency of 1.467 GHz, and peak power conversion efficiency of 14.0% when the voltage is 455 kV and the current is 48.7 kA. However, the peak power conversion efficiency of the relevant unfilled MILO is only 8.5%. The comparative result shows that the filled dielectric helps to enhance the power conversion efficiency of the DFMILO. In addition, the filled dielectric contributes to decrease the MILO's dominant frequency, which means that if the dominant frequency is same, the volume of the DFMILO (especially the low-frequency DFMILO) is more compact than that of the relevant unfilled MILO. [ABSTRACT FROM AUTHOR]

Based on coordinate transformation techniques, a simplified all-dielectric extraordinary-transmission device for broadband transmission through a subwavelength aperture is verified experimentally in this paper. The device is made from isotropic dielectric blocks with permittivity values ranging from 2.1 to 6. It is shown both numerically and experimentally that the device can provide transmission with a -3 dB bandwidth of more than 1 GHz, in a region which would otherwise be a stop band caused by the subwavelength aperture in an X-band waveguide. [ABSTRACT FROM AUTHOR]

This paper describes the quantitative force mapping of micron-sized particles held in an optical vortex trap. We present a simple and efficient model, which accounts for the diffraction of the strongly localized optical field of the tightly focused laser beam, the spherical aberration introduced by the dielectric glass-to-water interface, employs the multidipole approximation for force calculations, and is able to reproduce, with quantitative agreement, the experimentally measured force map. [ABSTRACT FROM AUTHOR]

This paper reports on an investigation into space charge formation and decay at dielectric interfaces. In particular, the influence of temperature on the formation of the trap deep has been studied. A multi-dielectrics structure composed of two dielectric films, Low Density Polyethylene (LDPE) and Fluorinated Ethylene Propylene (FEP), was subjected to an electric stress level of +14.3 kV/mm at two temperatures, 40 °C and 60 °C, and space charge measurements were taken using the pulsed electro-acoustic technique. Space charge distributions were investigated for combinations of LDPE/FEP flat specimens. The time dependence of the space charge distribution was subsequently recorded at different temperatures under short circuit (depolarization) conditions. It was found that temperature plays a significant role in space charge dynamics at the dielectric interface, charge mobility, electrical conductivity, filling of the trap, and the formation of the shallow trap. [ABSTRACT FROM AUTHOR]

This paper shows that a highly deformable capacitor made of a soft dielectric and two conformal electrodes can switch between two states discontinuously, by a first-order transition, as the total charge varies gradually. When the total charge is small, it spreads evenly over the area of the capacitor, and the capacitor deforms homogeneously. When the total charge is large, it localizes in a small region of the capacitor, and this region thins down preferentially. The capacitor will survive the localization without electrical breakdown if the area of the electrode is small. Such a bistable system may lead to useful devices. [ABSTRACT FROM AUTHOR]

Efforts by a number of institutions to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external radio frequency source have been ongoing over the past decade. Single surface resonant multipactor has been previously identified as one of the major limitations on the practical application of DLA structures in electron accelerators. In this paper, we report the results of an experiment that demonstrated suppression of multipactor growth in an X-band DLA structure through the use of an applied axial magnetic field. This represents an advance toward the practical use of DLA structures in many accelerator applications. [ABSTRACT FROM AUTHOR]

Traditional Luneburg lens is a dielectric spherical antenna. It can focus the incoming collimated electromagnetic waves on its spherical surface, which causes the incompatibility with the planar feeding and receiving devices. Furthermore, the difficulties in the fabrication process also limited its applications. In this paper, a three-dimensional flattened Luneburg lens with a field-of-view angle up to 180° has been realized based on a liquid medium approach and a 3D-printing process. The fabricated three-dimensional lens showed a broadband transmission characteristic from 12.4 GHz to 18 GHz. The performance of the proposed lens was demonstrated by simulation and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, the authors first report ZrO2-dielectric based low-voltage organic thin-film complementary metal-oxide semiconductor inverters. Two active layers of p-type pentacene and n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide were successively deposited on the thermally stable, transparent ZrO2 using the neutral cluster beam deposition method. Based on the good balance between p- and n-type transistors, the complementary inverters exhibited ideal characteristics including sharp inversions, complete switching, high gains, and large voltage swings at low operating voltage levels. [ABSTRACT FROM AUTHOR]

This paper reports optical emission spectroscopy measurements resolved laterally within a single microdischarge during the negative half-cycle of a sinusoidally driven dielectric barrier discharge. The maximum values of the reduced electric field, vibrational temperature of N2(C3Πu), and rotational temperature of N2+(B2Σu+) were approximately 300 Td, 3500 K, and 1200 K, respectively. These values were correlated to the outer-edges of the microdischarge near the plasma-dielectric surface interface. These maximum values were significantly greater than measurements made elsewhere within the microdischarge and suggest a strong sheath at the outer-edges of the microdischarge. [ABSTRACT FROM AUTHOR]

In this paper, we propose a physical method to manipulate the ice crystallization by applying an AC electric field during the liquid-solid transition of 0.9 wt. % NaCl aqueous solution. By using optical microscopic observation, we found that the ice grains are miniaturized in the presence of AC electric field during freezing process. Further study suggests that the grain size and the associated ice crystallization fraction are dependent on the field strength as well as frequency. And AC electric field can reduce the grain size and the crystallization fraction down to 35 μm and 71%, respectively, on the optimal condition (with field strength E = 100 kV/m, frequency f = 106 Hz). Moreover, the dielectric spectrum measurement of our sample close to transition temperature implies that such an optimal condition corresponds with a dielectric relaxation state, which might be the reason for the reduction of crystallized ice. Our finding may provide a potential way for cryoprotective application. [ABSTRACT FROM AUTHOR]

With the continuing aggressive scaling of interconnect dimensions and introduction of lower k materials, back-end-of-line (BEOL) dielectric time-dependent dielectric breakdown (TDDB) reliability margin is greatly reduced. In this paper, a comprehensive investigation on abnormal low-k TDDB characteristics, a systematic degradation of Weibull slopes, and a systematic increase of field acceleration at lower stress voltages due to massive Cu diffusion were conducted for Cu interconnect with low-k dielectric. Based on data from extensive electrical and physical analysis, such abnormal TDDB characteristics were attributed to slow metallic diffusion in bulk low-k under bias and temperature stress. A TDDB model based on invasion percolation was proposed to model the observed abnormalities. Cu interconnects with robust liner and capping layer, to ensure metal free low-k film, have become important for BEOL low-k TDDB. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrate a charge trapping memory with Au-Al2O3 core-shell nanocrystals (NCs) embedded in HfO2 high-k dielectric. Transmission electron microscopy images clearly show the Au NCs surrounded by Al2O3 shells in the HfO2 matrix. Electrical measurements show a considerable memory window (3.6 V at ±8 V), low program/erase operation voltages, and good endurance. Particularly, data retention is improved both at room temperature and high temperature compared to the NC structure without shell. An energy band model is given for the improved retention characteristic. This Au-Al2O3 core-shell NCs memory device has a strong potential for future high-performance nonvolatile memory application. [ABSTRACT FROM AUTHOR]

We would like to thank Zhao and Suo [Appl. Phys. Lett. 91, 061921 (2007)] for their insights and help on “Method to analyze electromechanical stability of dielectric elastomers;” Suo provided the theory of stability of dielectric elastomers. In this Comment, the nonlinear electromechanical theory for deformable dielectrics described in Suo’s paper is applied to analyze the stability of dielectric elastomers. Different from that given in Suo’s paper, in the current work, elastic strain energy functional with two material constants is used for the stability analysis. Dielectric materials with different values of k are analyzed, and the results seem to support Suo’s theory. These results can be applied in the design of dielectric elastomer actuator and in larger application spectrum. [ABSTRACT FROM AUTHOR]

Hydrogen-terminated diamond surfaces, emerging as a promising two-dimensional (2D) electron platform with great thermal and electronic properties, hold great potential for the next-generation high power and high frequency field effect transistor (FET). However, ideal gate dielectrics with high crystallinity and defect-free surfaces are still largely elusive. In this work, using the contamination-free pickup transfer method, hexagonal boron nitride (h-BN) flakes were fabricated on top of the hydrogen-terminated diamond surface to serve as a gate material and the passivation layer. The morphological and optical characterizations revealed the formation of homogeneous and intimate interface between h-BN and diamond. Benefiting from the h-BN gate dielectric layer, the maximum drain current density, subthreshold swing, and on/off ratio of diamond FET are measured to be −210.3 mA mm−1, 161 mV/dec, and 106, respectively. Especially, the transport measurement shows an almost constant Hall mobility of around 260 cm2 V−1 s−1 in the hole density range of 2 − 6 × 1012 cm−2, suggesting the excellent gate controllability of h-BN. Our results indicate that h-BN could form high-quality interface with hydrogen-terminated diamond, paving the way for the development of diamond-based electronic applications. [ABSTRACT FROM AUTHOR]

Functional dielectrics are a group of materials possessing interesting electro-active behaviors, such as variable permittivity, high breakdown strength, ferroelectricity, piezoelectricity, and pyroelectricity, resulting from their capacity to generate and respond to electric fields in a nonlinear manner. These properties make them highly desirable for energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

DyScO3 (DSO) is an attractive substrate on which to grow epitaxial thin films with extraordinary materials physics. However, its highly anisotropic permittivity makes some measurements exceedingly difficult: For instance, its permittivity tensor has not yet been fully characterized at millimeter-wave frequencies. While there are methods to characterize anisotropic permittivity at millimeter-wave frequencies, there are very few methods those are suitable for the small lateral dimensions that DyScO3 can be grown in. To overcome this lack in the material characterization, we tested an on-wafer method based on coplanar waveguides to measure the full anisotropic permittivity tensor from 0.1 to 110 GHz. We characterized two orthogonal sets of coplanar waveguides fabricated on each of two substrates with (001) and (110) crystallographic orientations to resolve the full permittivity tensor. To validate our measurements, we compared our results to data from dc parallel plate capacitors and THz time-domain spectroscopy. Our measurements fill the need for measurements of the permittivity of DyScO3, while the methodology, more generally, enables quantitative characterization of anisotropic dielectrics. [ABSTRACT FROM AUTHOR]

This study examines the low-frequency noise characteristics of the 2,7-dioctyl[1] benzothieno[3,2-b][1] benzothiophene organic thin-film transistor (OTFT) having a CYTOP dielectric layer. Specifically, the fabricated OTFT exhibits 1/f noise, and its behavior is explained via a carrier number fluctuation model. Additionally, the volume trap density (NT) of the gate dielectric is quantitatively evaluated and compared with its counterpart having SiO2 dielectric layer. The analysis of the results shows that the hydrophilic entities of the dielectric layer strongly influence the NT, while the CYTOP having hydrophobic properties provides less NT than that of SiO2. [ABSTRACT FROM AUTHOR]

The low surface charge density and consequent unsatisfactory energy conversion efficiency of nanogenerators hinder their capacious utility toward the emerging field of wearable electronics. The strategy of introducing dielectric fillers into a polymer matrix attempts to improve dielectric constant and, thereby, to enhance surface charge density but can hardly yield sufficient energy conversion efficiency. Herein, we report a high performance flexible and compressible triboelectric nanogenerator (FC-TENG) based on a lead-free dielectric material, potassium sodium niobate (KNN), embedded with Ti3C2Tx MXene fillers, blended into poly-vinyl alcohol (PVA) using an electrospinning technique. The role of MXene in dielectric functionalization is to promote the interfacial polarization effect by forming micro-capacitor structures or percolation systems and, thereby, to endow high charge-inducing and charge-trapping capabilities. As a result, the prepared 4 vol. % MXene loaded KNN/PVA nanofibers achieve a higher dielectric constant/dielectric loss factor, which leads to enhanced energy conversion efficiency of FC-TENGs with a maximum power density of ∼2780 mW/cm2. In addition, the selected device was employed into shoe-insoles to demonstrate its ability of capturing biomechanical energy, which reveals its potential to be utilized as a wearable power-source for next generation devices. [ABSTRACT FROM AUTHOR]

Fully solution-processed oxide thin-film transistors (TFTs) have shown a great potential in future printable electronics. However, high defect densities at the dielectric/channel interface have limited the simultaneous achievement of low operating voltage and high device performance. In this Letter, we study the effects of bilayer gate dielectrics in potential performance enhancement of solution-processed indium zinc oxide (IZO) TFTs. Several single and bilayer gate dielectrics are studied in terms of their physical and electrical properties. Compared with IZO TFTs using single-layer ZrOx gate dielectrics, optimized TFTs with ZrOx/AlOx gate dielectrics show an increase in carrier mobility and current on/off ratio by a factor of 3.5 and 27, respectively. The inner mechanisms of the performance enhancement are systematically studied, showing that the significantly improved TFT performance originates from the passivation effects of AlOx, which reduce the trap/defect states at the dielectric/channel interface by approximately an order of magnitude. With a low operating voltage of 2 V, a high mobility of over 10 cm2/V s, a subthreshold swing as low as 89 mV/dec, and a high current on/off ratio of >105, the reported devices might have a great potential in future low-cost, low-power printable electronics. [ABSTRACT FROM AUTHOR]

This paper presents an experimental investigation of the application of dielectric barrier discharge (DBD) plasma actuators on a slender delta wing to control the leading edge vortices (LEVs). The experiments are conducted in a wind tunnel with a Reynolds number of 50 000 based on the chord length. The smoke flow visualization reveals that the DBD plasma actuators at the leading edges significantly modify the vortical flow structure over the delta wing. It is noted that symmetric control at both semi-spans and asymmetric control at a single semi-span leads to opposite effects on the local LEVs. Particle image velocimetry (PIV) indicates that the shear layer is deformed by the actuators. Therefore, both the strength and the shape of the LEV cores are deeply affected. The six-component force measurement shows that the DBD plasma actuators have a limited effect on lift and drag while inducing relatively large moments. This suggests that the DBD plasma actuator is a promising technique for delta wing maneuvering. [ABSTRACT FROM AUTHOR]

The resistive switching between high impedance ('off' state) and low impedance ('on' state) is demonstrated on e-beam evaporated SiOx/Si resistive random access memory devices in this paper. The set and reset voltages are independent of the device perimeters and oxide thicknesses after electroforming. A circuit model including filament conductance G is proposed to explain the measured 'on' state capacitances under frequency ranges from 1 KHz to 1 MHz. The electrochemical redox process is adopted to explain the formation of Si filament during electroforming and switching. 'On' and 'off' currents were also measured at various operating temperatures. It is found that both set and reset voltages increase as temperature decreases and that no electroforming is exhibited at low temperature T = 77 K. [ABSTRACT FROM AUTHOR]

The effectiveness of an atomic layer deposited beryllium oxide (BeO) barrier layer has been investigated through physical and electrical analysis as a way to control the interfacial layer on Si and III-V substrates recently. In this paper, a theoretical model is suggested to find the most promising gate dielectric based on electromagnetic interactions between the channel carrier and atoms in the gate dielectric, as well as the structural stability of the gate dielectric. Using this model, Al2O3, BeO, SiO2, and HfO2 were evaluated as gate dielectrics for Si and III-V metal oxide semiconductor devices. [ABSTRACT FROM AUTHOR]

Polymer dielectrics for electrostatic capacitors possess well-recognized advantages, including ultrahigh power density, excellent processability, and unique self-healing capability. Nevertheless, the negative coupling relationship between dielectric permittivity and breakdown strength in dielectrics always constrains the enhancement of energy density, which cannot satisfy the ever-increasing requirements for integrated and miniaturized technologies. Here, a kind of C/SiO2@TiO2 triphase nanoparticle (CST NP) with a hybrid-core satellite structure is prepared and introduced into nonlinear poly(vinylidene fluoride-co-hexafluoropylene) [P(VDF-HFP)] matrix to improve permittivity and polarization. Benefited from the intensified interfacial polarization induced by CST NPs, a high permittivity of ∼18.8, which is approximately 219% that of pure P(VDF-HFP) (∼8.6), is obtained at 10 kHz. Meanwhile, a linear PEI film with high breakdown strength is stacked with the CST/P(VDF-HFP) composites, forming linear/nonlinear CST/P(VDF-HFP)-PEI bilayer composites. Eventually, a high breakdown strength of ∼503.9 kV/mm, a high energy density of ∼4.26 J/cm3, and a high efficiency of ∼91% are simultaneously achieved in the bilayer composite with merely 0.75 wt. % nanoparticles. The linear/nonlinear bilayer structure incorporated with hybrid-core satellite nanofillers offers an effective strategy to design high-performance dielectric energy storage materials. [ABSTRACT FROM AUTHOR]

The rapid development of electrostatic capacitors puts forward more stringent requirements for the use of polymer dielectrics, that is, to maintain high energy storage density and efficiency under extreme environments of high temperature and high electric field. In this work, all-organic composites comprising polyetherimide (PEI) blended with high-electron-affinity polymer dots (PDs) have been fabricated and modified by UV irradiation. It is found that the UV irradiated all-organic composites exhibit high energy density (4.1 J cm−3), far outperforming pristine PEI. The energy level diagram and electric conduction results prove that PDs capture free electrons via electrostatic attraction and the wide bandgap forms a barrier to electron transport, which inhibits the electric conduction, leading to the substantial performance improvements. This work demonstrates an effective modification method for the improvement of high-temperature electronics and energy storage devices. [ABSTRACT FROM AUTHOR]

AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) were demonstrated to operate at temperatures of up to 600 °C. High-quality multilayer gate dielectrics (Al2O3/SiO2/SiON) were developed to enhance the thermal stability of the MIS-HEMTs at high temperatures. Furthermore, we found that silicon nitride passivation and circular structure can effectively reduce the off-state drain current, which is critical for high-temperature operations. Based on the optimized process, we demonstrated the AlGaN/GaN MIS-HEMTs with record high I o n / I off ratios (1011 at room temperature and 105 at 600 °C) and high transconductances (47 mS/mm at room temperature and 8 mS/mm at 600 °C for a channel length of 2.4 μm). The maximum transconductance was enhanced by ∼28% after the operation at 600 °C. Lifetime measurement of the MIS-HEMT showed stable DC characteristics with a nearly unchanged on-state drain current and threshold voltage over the course of 25-h thermal stress at 525 °C. [ABSTRACT FROM AUTHOR]

Charging by means of dielectric barrier discharges (DBDs) is a critical step in the preparation of ferroelectrets (also called piezoelectrets). Triggering of the DBD charging in ferroelectrets is governed by Paschen's law. The Paschen-breakdown voltage V b of common gases exhibits a U-shaped dependence on the product of gas pressure p and electrode spacing d (internal-cavity height in the present ferroelectret context). This allows for a more efficient charging strategy for ferroelectrets whose pd value at atmospheric pressure is different from the (p d) min value of the Paschen-breakdown curve. For easier triggering of the DBD charging, the pd is adjusted toward (p d) min (corresponding to V b , min of the Paschen curve) by controlling the gas pressure in the cavity. Subsequently, pd is restored to its value at ambient pressure under the charging voltage in order to obtain a high remanent polarization. The proposed charging scheme is easy to operate and can significantly improve the charging efficiency of ferroelectrets with a wide range of cavity geometries. [ABSTRACT FROM AUTHOR]

Fermi level pinning near GaSb valence band edge leads to high Schottky barrier height for metal/n-type GaSb contacts. However, this effect can be alleviated by depinning of the Fermi level with the introduction of thin interfacial dielectric. In this paper, the use of TiO2 allows depinning of the Fermi level without introducing excessive tunneling resistance due to the low conduction band offset, estimated by synchrotron radiation photoemission spectroscopy. It is shown the insertion of TiO2 results in reduction in Schottky barrier height and greater than four orders of magnitude increase in current density for metal contacts on n-type GaSb. [ABSTRACT FROM AUTHOR]

The paper attempts to elaborate on the basic problem of dielectric charging in insulating films for microelectromechanical capacitive switches, the dependence of the film electrical properties on material stoichiometry and the uncertainty of whether the implementation of a leaky dielectric would reduce the charging effects. Silicon nitride films with stoichiometries (N/Si) ranging from 0.36 to 0.85 were assessed in metal-insulator-metal capacitors using the thermally stimulated depolarization current method and by obtaining the current-voltage characteristics. Capacitive switches were also fabricated with the same dielectric films. Results from both devices revealed an enhanced charging in the case of silicon-rich films. [ABSTRACT FROM AUTHOR]

In this paper, an analytical model of trapping in high-k dielectrics is proposed. It starts from the general rate equation and relies on the hypothesis that the density of states involved in the capture mechanism follows a Fermi-like distribution. Thus, the energy depth of the trap level respect to the Fermi level is explicited in the model. The model is validated comparing predictions of flat band shift (calculated integrating the density of involved states) with experimental curves measured on GdSiO metal-oxide-semiconductor capacitors in many different conditions. The energy level of the trap is extracted. [ABSTRACT FROM AUTHOR]