Effective Gate Research Articles

A Transition Metal Dichalcogenide Tunnel FET-Based Waveguide-Integrated Photodetector Using Ge for Near-Infrared Detection

This paper presents a novel approach for the design of a waveguide-integrated photodetector that combines the advantage of atomically thin MoS2 tunnel FET (TFET) with infrared detection capability of Germanium (Ge). The Ge layer acting as a photogate for underlying TFET is optimized to have good optical confinement of guided mode traveling in the SOI rib waveguide. The low-power operation, effective gate control, low OFF-state current, and improved subthreshold characteristics of MoS2 TFET effectively enhance the detector performance for on-chip applications. Due to the high sensitivity of the TFET in the subthreshold region, an addition of the photovoltage to the gate voltage increases the band-to-band tunneling (BTBT) significantly, showing good photoresponse. The analytical and simulation results illustrate that at 1550 nm wavelength with an incident optical power intensity of 3 Wcm−2, a maximum responsivity of 2700 AW−1 and an ON–OFF ratio ( $I_{ON}/I_{OFF}$ ) of 107 is obtained. The device shows good spectral sensitivity with a low dark current.

Inner-Gate-Engineered GAA MOSFET to Enhance the Electrostatic Integrity

Gate-all-around (GAA) MOSFETs are the best multi-gate MOSFET structure due to their strong electrostatic control over the channel. The electrostatic controllability can be enhanced further by applying some gate engineering technique to the existing GAA structure. This paper investigates the effect of inner gate (core gate) on the electrostatic performance of conventional GAA MOSFET. The inner gate engineering increases both the electrostatic control and packing density of GAA MOSFET. In this paper, we have presented an inner-gate-engineered (IGE) GAA MOSFET and inspected its advantages over conventional counterparts. The proposed structure exhibits higher [Formula: see text] ratio, low threshold voltage and improved RF performances as compared to the conventional structure. Analytic simulation has been carried out for numerous figures of merit (FOMs) for different technology nodes.

Highly sensitive nitrite sensor based on AuNPs/RGO nanocomposites modified graphene electrochemical transistors

Detection of nitrite is important for environmental safety and human health, and the development of high-performance sensors for accurate detection of nitrite is highly desirable. Herein, a highly sensitive graphene electrochemical transistor (GECT) nitrite sensor was designed and fabricated for the first time. A single layer of graphene was placed between the source and drain electrodes by the wetting transfer method to act as channel for the transistor. Au nanoparticles modified reduced graphene oxide nanocomposites (AuNPs/RGO) were electrodeposited at the transistor gate to improve its catalytic oxidation performance of nitrite with optimized electrodeposition conditions. The sensing principle was attributed to changes in effective gate voltage applied to GECT induced by electrooxidation of nitrite at gate electrodes. Due to the high carrier mobility of graphene in the channel and the excellent electrocatalytical activity of AuNPs/RGO on the gate, the obtained sensor device exhibited an exceedingly low detection limit (0.1 nM nitrite) and ultra-wide linear range from 0.1 nM to 7 μM and from 7 to 1000 μM, which are comparable or superior to the performance of large-scale instruments (e.g. chromatography, spectrophotometry, and spectrofluorimetry etc.). The GECT device also showed good anti-interference performance toward common interfering ions and stable performances. Nitrite in natural lake water has been proven to be monitored by our devices. Therefore, the present novel GECT sensor could act as a desirable practical platform for highly sensitive detection of nitrite in the food and environmental fields.

A Dual-Switch Discontinuous Current-Source Gate Driver Overcoming the Current Diversion Problem for a Buck VRM

In this article, a novel dual-switch discontinuous current-source gate driver (CSD) suitable for driving the high-side mosfet (HS mosfet ) of buck voltage regulator module (VRM) is presented. The proposed gate driver completely solves the gate current diversion problem, which most of the previous CSDs suffer from, during turn- off transition. Thus, in comparison to most of the previous CSDs, the proposed gate driver achieves to turn- off the power mosfet considerably faster and with much higher effective gate current, which leads to significant reduction of turn- off losses. Whereas, turn- on losses of buck VRM HS mosfet driven by the proposed CSD and the previous CSDs are equal. Furthermore, the introduced gate driver consists of the minimum number of control switches and circuit elements, compared to previous CSDs. The proposed gate driver is analyzed and a prototype of the driver operating at 1 MHz is implemented in order to validate the theoretical analysis.

Frequency-, Time-, and Wavevector-Resolved Ultrafast Incoherent Diffraction of Noisy X-ray Pulses.

We study theoretically incoherent time-resolved X-ray diffraction of fluctuating sources such as free electron lasers, as well as coherent sources with controllably added randomness. We find that the temporal resolution is strongly eroded by the noise. By considering frequency resolution of the signal, we find that the statistical properties of the noise carry important information allowing us to restore the temporal resolution. We propose a multidimensional stochastic resonance treatment to shape the optical window and extract this information from signals. Using the frequency-dependent stochastic phase as a frequency marker allows to improve the spectral resolution as well via intensity correlations. Frequency-tuned field correlation functions are used to modify the effective frequency gating and extract specific charge density contributions to the diffraction pattern while maintaining temporal resolution.

Adiabatic and high-fidelity quantum gates with hybrid Rydberg-Rydberg interactions.

Rydberg blockaded gate is a fundamental ingredient for scalable quantum computation with neutral Rydberg atoms. However the fidelity of such a gate is intrinsically limited by a blockade error coming from a Rydberg level shift that forbids its extensive use. Based on a dark-state adiabatic passage, we develop a novel protocol for realizing a two-atom blockade-error-free quantum gate in a hybrid system with simultaneous van der Waals (vdWsI) and resonant dipole-dipole interactions (DDI). The basic idea relies on converting the roles of two interactions, which is, the DDI serves as one time-dependent tunable pulse and the vdWsI acts as a negligible middle level shift, as long as the adiabatic condition is preserved. We adopt an optimized super-Gaussian optical pulse with kπ(k ≫ 1) area accompanied by a smooth tuning for the DDI, composing a circular stimulated Raman adiabatic passage, which can robustly ensure a faster operation time ∼ 80ns as well as a highly-efficient gate fidelity ∼ 0.9996. This theoretical protocol offers a flexible treatment for hybrid interactions in complex Rydberg systems, enabling on-demand design of new types of effective Rydberg quantum gate devices.

Learning to Write Stories with Thematic Consistency and Wording Novelty

Automatic story generation is a challenging task, which involves automatically comprising a sequence of sentences or words with a consistent topic and novel wordings. Although many attention has been paid to this task and prompting progress has been made, there still exists a noticeable gap between generated stories and those created by humans, especially in terms of thematic consistency and wording novelty. To fill this gap, we propose a cache-augmented conditional variational autoencoder for story generation, where the cache module allows to improve thematic consistency while the conditional variational autoencoder part is used for generating stories with less common words by using a continuous latent variable. For combing the cache module and the autoencoder part, we further introduce an effective gate mechanism. Experimental results on ROCStories and WritingPrompts indicate that our proposed model can generate stories with consistency and wording novelty, and outperforms existing models under both automatic metrics and human evaluations.

Scheme for generation of three-photon entangled W state assisted by cross-Kerr nonlinearity and quantum dot

We represent an optical scheme using cross-Kerr nonlinearities (XKNLs) and quantum dot (QD) within a single-sided optical cavity (QD-cavity system) to generate three-photon entangled W state containing entanglement against loss of one photon of them. To generate W state (three-photon) with robust entanglement against loss of one photon, we utilize effects of optical nonlinearities in XKNLs (as quantum controlled operations) and QD-cavity system (as a parity operation) with linearly optical devices. In our scheme, the nonlinear (XKNL) gate consists of weak XKNLs, quantum bus beams, and photon-number-resolving measurement to realize controlled-unitary gate between two photons while another nonlinear (QD) gate employs interactions of photons and an electron of QD confined within a single-sided optical cavity for implementation of parity gate. Subsequently, for the efficiency and experimental feasibility of our scheme generating W state, we analyze the immunity of the controlled-unitary gate using XKNLs against decoherence effect and reliable performance of parity gate using QD-cavity system.

Ga2O3 metal-oxide-semiconductor field effect transistors on sapphire substrate by MOCVD

Si-doped gallium oxide (Ga2O3) thin films were grown on a c-plane sapphire substrate by metalorganic chemical vapor deposition (MOCVD) and fabricated into metal oxide semiconductor field effect transistors (MOSFETs). The Ga2O3 MOSFETs exhibited effective gate modulation of the drain current with a complete channel pinch-off for VG < −25 V, and the three-terminal off-state breakdown voltage was 390 V. The device shows a very low gate leakage current (∼50 pA mm−1), which led to a high on/off ratio of ∼108. These transistor characteristics were stable from room temperature to 250 °C.

Analysis of Gain Variation With Changing Supply Voltages in GaN HEMTs for Envelope Tracking Power Amplifiers

Envelope tracking (ET) is a promising power amplifier (PA) architecture for current and future communications systems, which uses dynamic modulation of the supply voltage to provide high efficiency and potentially very wide bandwidth over a large dynamic range of output power. However, the dynamic nature of the supply voltage can lead to a problematic variation in transistor gain, particularly in GaN HEMTs. This paper describes and analyzes this behavior and the detrimental effect it can have on ET PAs. Contributing factors and origins of gain variation are described in detail along with how, for the first time, meaningful comparisons can be made between different devices. Using these guidelines, gain variation is shown to be a widespread issue effecting most GaN HEMTs presented in literature. To allow an analysis of the intrinsic device behavior, an extended transistor model is developed that takes the effect of gate and source field plates into account. This model is refined using measurement data and used to demonstrate the fact that the parasitic gate–drain capacitance ( $C_{\textrm {GD}}$ ) is the main contributor to the small-signal gain variation—a significant part of the overall gain variation. Based on this knowledge, possible strategies to reduce gain variation at the transistor technology level are proposed, allowing the optimization of GaN HEMTs specifically for ET PAs. One identified strategy involves reducing the length of the gate field plate and is shown to be a viable approach to reduce the gain variation in GaN HEMTs, albeit at an increased RF/dc dispersion.

Performance Characteristics in BMX Racing: A Scoping Review.

Performance characteristics across a number of cycle sports have been investigated for decades. However, evidence suggests little is known about the performance characteristics in BMX cycling. As a result, a scoping review was undertaken to explore the quantity and themes of research in this area. After adopting the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRIMSA) guidelines 104 studies were identified in the initial search and post screening 17 studies were identified as relevant. These studies were categorised into two sub categories; physical and technical characteristics. The first category, physical performance characteristics included ten studies that analysed torque, cadence, and peak power in relation to velocity and time to peak power. The remaining 7 studies related to technical attributes and focused on the development of an effective gate start technique or analysed techniques deemed important during a BMX race. In addition to the categories, 9 of the 17 studies identified in this review reported reliability issues in collecting performance characteristic data, as well as issues surrounding transference of data from the laboratory to the BMX track. Future research should consider intervention studies examining how time to peak power could be developed and the effect this would have on the start of a BMX race. Future studies may also consider using equipment with higher levels of reliability and testing riders in the track environment. Moreover, this scoping review could serve as a starting point for a systematic review.

Estimation of Reservoir Sediment Flux through Bottom Outlet with Combination of Numerical and Empirical Methods

Sediment deposition issues for reservoirs are important in Taiwan because the severe deposition could excessively decrease the reservoir lifecycle. Extreme storm events usually can carry a massive amount of sediment into reservoirs, and deposition will happen unless the incoming material can pass through sluice gates. When it comes with high concentration, the density current flow is prone to be generated, and the bottom outlets are the most effective sluice gate to release the sediment. In order to improve the sediment release efficiency, an accurate estimation of arriving concentration and time of the density current can be useful for the reservoir management. This study develops a two-stage approach which combines a numerical model (SRH2D) and the modified Rouse equation to predict the sediment flux of the reservoir. The numerical model was verified and applied to establish the relation between inflow and dam face concentration. The modified Rouse equation then adopted this relation to estimate the proper exponential parameter. As a result, the sediment flux amount at each bottom outlet can be accurately predicted by this equation. With this means, an early warning system can be established for reservoir operation, which can improve release efficiency during typhoons.

Modeling of contact resistance effect on low frequency noise in indium–zinc oxide thin-film transistors

Low frequency noise in the indium–zinc oxide thin-film transistors (IZO TFTs) at low drain voltage is investigated in this paper. First, the contact resistance is extracted from transfer characteristics. By analyzing the noise behavior under different bias conditions, the measured noises in IZO TFTs have been separated into contributions from the channel and contacts. Determined by the channel and the contact, the normalized noise varied with two slopes ([Formula: see text] and 2) with the increment of effective gate voltage. Moreover, the values of flat-band voltage noise spectral density and Coulomb scattering parameter have been extracted. By considering contact resistance, the normalized noise has also been modeled by the use of carrier number with the correlated mobility fluctuation [Formula: see text] model.

Scaled dielectrics for scaled devices

Ultrathin calcium fluoride layers can provide an effective gate dielectric for two-dimensional transistors.

Size of Heparin-Imprinted Nanoparticles Reflects the Matched Interactions with the Target Molecule.

It has been shown that the faradic current at an electrode grafted with molecularly imprinted polymer (MIP) is sensitive to the specific target molecule used as the template. This phenomenon is applicable to sensors with very high selectivity, but the sensing mechanism is still a black box. We investigated the size sensitivity of nanoparticles of molecularly imprinted polymers (MIP-NPs) to a specific interaction for determination of the mechanism of the gate effect and its feasibility for new applications. Nanoparticles of poly(methacryloxy ethyl trimethylammonium chloride-co-acrylamide-co-methylenebisacrylamide) imprinted with heparin immobilized on glass beads were synthesized. The diameter of the MIP-NPs of heparin was increased by the presence of the heparin template but was insensitive to chondroitin sulfate C (CSC), the analogue of heparin. The high selectivity of the MIP-NPs was consistent with the selectivity of electrodes grafted with a heparin-imprinted polymer in our previous studies. The quartz crystal microbalance probes immobilizing heparin or CSC were sensitive to MIP-NPs, which indicates that the binding ability of MIP-NP does not discriminate between the template and other glycosaminoglycans. These results indicate that the size of the MIP-NP is sensitive to the matched binding with the template through the imprinted cavity.

"Gate Effect" in p-Synephrine Electrochemical Sensing with a Molecularly Imprinted Polymer and Redox Probes.

The "gate effect" mechanism for conductive molecularly imprinted polymer (MIP) film coated electrodes was investigated in detail. It was demonstrated that the decrease of the DPV signal for the Fe(CN)64-/Fe(CN)63- redox probe with the increase of the p-synephrine target analyte concentration in solution at the polythiophene MIP-film coated electrode did not originate from swelling or shrinking of the MIP film, as it was previously postulated, but from changes in the electrochemical process kinetics. The MIP-film coated electrode was examined with cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and surface plasmon resonance (SPR). The MIP-film thickness in the absence and in the presence of the p-synephrine analyte was examined with in situ AFM imaging. Moreover, it was demonstrated that doping of the MIP film was not affected by p-synephrine binding in MIP-film molecular cavities. It was concluded that the "gate effect" was most likely caused by changes in radical cation (polaron) mobility in the film.

Performance analysis of nanoscale double gate strained silicon MOSFET with high k dielectric layers

This study presents a theoretical model to describe the combined characteristics of strained silicon nanoscale double gate MOSFET along with high k dielectric layer. Although a well- tempered MOSFET with strong gate electrostatics can be devised using high k gate material, lower conduction band offset (CBO) over silicon results in leakage and subsequent static power dissipation. The study shows that this effect can reduce the Ion/Ioff ratio to 2 × 102 with 2 nm thick TiO2 dielectric layer (k = 60) along with mobility degradation. Incorporating the effects of strained silicon and high k dielectrics in MOSFETs exhibits bandstructure alteration and increase in CBO. This inhibits carrier tunnelling causing leakage with restoration of Ion/Ioff ratio to 4.5 × 106. The mobility can also be improved along with the maintenance of effective gate electrostatics. Thus the study illustrates the possibility of designing the nanoscale MOS devices with all the essential characteristics without trade-off over other performance parameters.

Low-Voltage-Manipulating Spin Dynamics of Flexible Fe3O4 Films through Ionic Gel Gating for Wearable Devices.

Mechanical flexible electronic/spintronic devices have shown enormous application potential to impact our daily life. Here, an in situ low-voltage-controlled flexible field-effect transistor structure was exploited, which consists of a support layer (mica), functional layer (Fe3O4), and control layer (ionic gel). By applying a low voltage (1.5 V) on the ionic gel, the spin-dynamic properties of the function layer were manipulated and a reversible, nonvolatile 345 Oe ferromagnetic resonance field ( Hr) shift was achieved, which corresponds to a large magnetoelectric (ME) coefficient of 230 Oe/V. In addition, a reversible 126 Oe Hr shift (84 Oe/V) was obtained when the layers were bent at curvature radius r = 15 mm. The ME tunability could be attributed to the E-field induced ionic transformation between Fe2+ and Fe3+ at the interface via electrostatic induction. This sandwich structure shows an excellent and effective ionic gel gating system and paves the way for low-voltage-tunable, nonvolatile, and flexible spintronic devices such as memory devices, sensors, and logical devices.

Temperature-Dependent Low-Frequency Noise in Indium–Zinc–Oxide Thin-Film Transistors Down to 10 K

The carrier transport mechanisms in indium–zinc–oxide thin-film transistors are investigated in this paper by use of low-frequency noise (LFN). First, LFNs are measured in the range from 10 to 300 K. The measured noises show that the device is varied from an interface-dominated device to a bulk-dominated device at lower temperature, which induce to the variation of the power coefficient of normalized noise against the effective gate voltage. Moreover, the measured noise increases with decreasing temperature in the range of 200–300 K. Below 200 K, the measured noise decreases with the decrement of temperature, which dominated by thermally activated conduction mechanism in the range of 80–200 K and dominated by variable range hopping theory below 80 K. The variations of flat-band voltage spectral density and average Hooge’s parameter with temperature are also extracted and discussed. The calculated fluctuation related defects increase significantly with decreasing temperature.

Selectively Metallized 2D Materials for Simple Logic Devices

We herein demonstrate, for the first time, transparent, flexible, and large-area monolithic MoS2 transistors and logic gates. Each single transistor consists of only two components: a monolithic chemical vapor deposition-grown MoS2 and an ion gel. Additional electrode materials are not required. The uniqueness of the device configuration is attributed to two factors. One is that a MoS2 layer is a semiconductor, but it can be doped degenerately; monolithic MoS2 can thus serve as both the electrodes and the channel of a transistor via selective doping of the material at certain positions. The other is the use of an electrolyte gate dielectric that permits effective gating (<3 V) even from an electrode coplanar with the channel. The resulting monolithic MoS2 transistors yield excellent device performance, including a maximum mobility of 1.5 cm2/V s, an on-off ratio of 105, and a turn-on voltage of -0.69 V. This unique transistor architecture was successfully applied to various semiconductors such as ReS2 and indium-gallium-zinc oxide. Furthermore, the presented devices exhibit excellent mechanical, operational, and environmental stabilities. Fabrication of complex logic circuits (NOT, NAND, and NOR gates) by integration of the monolithic MoS2 transistors is demonstrated. Finally, the monolithic MoS2 transistor was connected to drive red, green, and blue light-emitting diode pixels, which yielded high luminance at a low voltage (<3 V). We believe that the unique architecture of the devices provides a facile way for low-cost, flexible, and high-performance two-dimensional electronics.