Electric Field Research Articles

Dual-gate AlGaN channel HEMTs: advancements in E-mode performance with N-shaped graded composite barriers

Abstract This work evaluates the performance of dual gate AlGaN channel HEMTs on SiC substrate. The study analyzes two HEMT structures that differ only in barrier design, one design consists of fixed composite barriers (FCB-HEMT) i.e. there is fixed Aluminum composition x = 0.48 in the first Al x Ga1−x N barrier and x = 0.42 in the second Al x Ga1−xN barrier while the other design comprises N-shaped graded composite barriers (NGCB-HEMT) i.e. the Aluminum content varies gradually from 0.4 to 0.48 in the first AlGaN barrier and from 0.34 to 0.42 in the second AlGaN barrier. The paper concentrates on energy band diagrams, electron concentration profile, electric field distribution, drain and transfer characteristics, and the effects of high temperature on drain characteristics and mobility of the NGCB-HEMT. It has been reported that at zero gate bias, the FCB-HEMT has a drain current density of 0.137 A mm−1 while it decreases to 0.0058 A mm−1 in the case of NGCB-HEMT, thus presenting a novel approach towards enhancement-mode AlGaN HEMTs. Hence, grading can be optimized in the composite barriers to achieve enhancement mode operation of AlGaN channel HEMTs. Furthermore, the study reveals that the critical electric field of FCB-HEMT is 6.9975 M V cm−1, while that of NGCB-HEMT is 5.3124 M V cm−1, demonstrating their usefulness in electronic devices that operate at high voltages and harsh temperatures. Moreover, at higher temperatures, the phenomenon of optical phonon scattering leads to decreased mobilities, which in turn causes low drain currents relative to the drain voltage.

Direct observation of space-charge-induced electric fields at oxide grain boundaries.

Space charge layers (SCLs) formed at grain boundaries (GBs) are considered to critically influence the properties of polycrystalline materials such as ion conductivities. Despite the extensive researches on this issue, the presence of GB SCLs and their relationship with GB orientations, atomic-scale structures and impurity/solute segregation behaviors remain controversial, primarily due to the difficulties in directly observing charge distribution at GBs. In this study, we directly observe electric field distribution across the well-defined yttria-stabilized zirconia (YSZ) GBs by tilt-scan averaged differential phase contrast scanning transmission electron microscopy. Our observation clearly reveals the existence of SCLs across the YSZ GBs with nanometer precision, which are significantly varied depending on the GB orientations and the resultant core atomic structures. Moreover, the magnitude of SCLs show a strong correlation with yttrium segregation amounts. This study provides critical insights into the complex interplay between SCLs, orientations, atomic structures and segregation of GBs in ionic crystals.

Electrostatic potential measurement of floating conductive objects: Some theoretical considerations and experimental results

The measurement of electrostatic potentials of floating conductive objects can, in principle, be performed by well-known basic experimental setups. Commercial equipment is readily available and the physical principles underlaying the problem are well established. However, electrostatic measurements require special attention, as significant errors can arise from the influence of the measuring setup or the misinterpretation of the results. First, the specificity of the measuring equipment must be well understood such as the difference between field mills, induction probes and feedback probes (also called electrostatic probes). These instruments create specific boundary conditions around the object being measured such as the introduction of grounded planes or the cancellation of the electric field. This influence is particularly significant when measuring floating objects as, for example, belts and suspended or flying objects. Even when results are provided directly in volts, their interpretation varies greatly depending on the instrument used. In the case of the field mills measurements, a calibration must be performed to convert the measured electric field into the potential of the floating object. This calibration is often performed by applying a known potential to the floating object. However, this procedure may introduce errors in the measured values due to the presence of the high voltage cable used to charge the object. We describe some examples of numerical calculations and show some experimental measurements on a levitating object.

Research Progress on the Effect and Mechanism of Superchilling Preservation Technology on Meat Quality Control.

During storage and transportation, meat is susceptible to the effects of microorganisms, endogenous enzymes, and oxygen, leading to issues such as moisture loss, spoilage, and deterioration. Superchilling, as a preservation method that combines the benefits of refrigeration and freezing, can effectively slow the growth and reproduction of microorganisms, control protein and lipid oxidation, reduce water loss, and maintain the quality and sensory properties of meat. This paper reviews the current application status of superchilling technology in meat preservation, focusing on the mechanisms of ice crystal formation, water retention, tenderness preservation, protein and fat oxidation control, and microbial growth inhibition under superchilling conditions. Additionally, it summarizes the research progress on the combined application of superchilling with emerging technologies such as electric fields, magnetic fields, and electron beams in meat preservation and explores its potential and future prospects for improving meat quality. The aim is to provide scientific evidence and technical support for the application of superchilling technology in enhancing meat quality.

Extreme electromagnetic rotation, chemical reaction, Hall and ion slip effects on weakly ionized fluid in a Riga channel

The utilization of external magnetic or electric fields, particularly through a Riga setup, markedly enhances flow dynamics by mitigating frictional forces and turbulent fluctuations, thereby facilitating superior flow management. Such improvements are especially beneficial in optimizing the operational efficiency of machinery and turbines. Our research focuses on the behaviour of a weakly ionized fluid within a porous, infinitely extended Riga channel (or electromagnetic channel) set in a rotational frame work affected by Hall and ion-slip electric fields. This model integrates the cumulative repulsions of an abruptly apply pressure gradients, electro-magnetic force, electromagnetic radiation, as well as chemical reactions. The physical configuration of the model features a stationary RHS wall as well as the LHS wall subjected to transversal vibration, establishing a complex flow environment. This circumstance is analytically modeled utilizing time dependent PDE, with the Laplace transform method applied to achieve a closed-format resolution for the course controlling equations. Through detailed graphical and tabular data, the investigations explored the impacts of assorted pivotal parameters on the model's flow traits and quantities. Our results indicate that an upswing in the modified Hartmann number significantly enhances fluids flow in the conduit, with the most important resultant flow showing marked improvement as Hall and ion-slip parameters amplify, and secondly the resultant flow diminishing chemical reaction parameter. Additionally, species concentration lowers with higher Schmidt numbers and chemical reaction rates, while an expanded modified Hartmann number correlate with enhanced shear stress near the conduit wall. Moreover, an elevation in the radiating parameter reduces the rate of temperature transport at the vibrating wall, whereas this at the stationary wall improves. This study has profound implications across several fields, notably in fusion energy research, spacecraft propulsion systems, satellite operations, aerospace engineering, and advanced manufacturing technologies.

Piezoelectric energy harvests by the usage of a laminar pulsating flow circulating in a rectangular channel

Abstract This work develops a theoretical study of a piezoelectric energy harvester, perturbed through a fully developed laminar flow with an oscillating pressure gradient. Considering a fully developed hydrodynamic flow, the electric energy generated in the piezoelectric element is due only to shear stresses yielded at the inner surfaces of the channel. In this manner, a fraction of the viscous forces is converted into unitary deformations at the piezoelectric, and the other fraction is transformed to induced electric piezoelectric energy.
Using dimensionless analysis, the formulation of resulting dimensionless governing equations for the fluid and the corresponding deformation and electric potential fields for the piezoelectric material constitute a conjugate problem, solved by considering harmonic solutions. Although the dimensionless power output is a multi-parametric function, due to the large number of dimensionless parameters involved, we find that
the main behavior of the electrical power depends very sensitively on two fundamental dimensionless parameters: the Womersley number, α, associated with the oscillating flow and a parameter that measures the physical importance of the electrical energy produced by the action of the velocity field. For the first case, it is seen that the power increases if the Womersley number is decreased while for the second case, the inverse behavior is predicted. Therefore, there is a clear operation of the physical system for which better conditions can be reached by selecting and varying appropriately the assumed values of different dimensionless parameters.

A Tunable Transparent Graphene Absorber with Multifrequency Resonance

AbstractThe demand for multinarrowband absorber has attracted increasing interest among researchers in recent years. However, integrating multifrequency absorption, tunability, and high optical transparency into an absorber remains a crucial challenge. In this study, a multiband, tunable, and transparent microwave meta‐absorber is theoretically proposed and experimentally demonstrated. This meta‐absorber is composed of resonant patterns made from graphene and indium tin oxide (ITO), placed on a substrate of lithium niobate (LN). By introducing P‐type doping to reduce the resistance of monolayer graphene to around 300 Ω, the impedance matching of the absorber is promoted, consequently manifesting ten absorption points within 40 GHz. The electric field distribution analysis and an equivalent circuit model are employed to elucidate the physical mechanisms of the multiband absorber. Additionally, the lithium niobate dielectric layer possesses a substantial dielectric constant and exhibits phase transition characteristics with temperature changes. When the temperature increases to 250 °C, a comprehensive tuning range of more than 5.49 GHz within 40 GHz range is realized. The maximum tuning range for a single frequency point is 1.33 GHz. With the broadening of the band, the meta‐absorber can provide multiple tunable ranges, making it more favorable for practical applications in optical modulator and sensor.

A scattering matrix approach to the effective mass dependence of tunneling current through heterojunctions

A scattering matrix technique is used to calculate the longitudinal and transverse energy dependence of the transmission probability through various heterostructures using both the BenDaniel–Duke (BD) and the lesser known Zhu–Kroemer (ZK) boundary conditions to take into account the spatial dependence of the effective mass. We first illustrate the large difference in the transmission probabilities calculated using both boundary conditions for the simple problems of tunneling through a potential step, a single rectangular barrier, and a resonant tunneling device. Then, we present numerical calculations of the external electric field dependence of the field emission (FE) current from a n-doped GaAs semiconductor/vacuum interface using both boundary conditions, showing that the BD boundary conditions underestimate the FE current for large values of the applied external electrostatic field. A comparison of calculated FE characteristics with FE data may be a way to determine the appropriate boundary conditions to solve tunneling problems through heterostructures with spatially varying effective mass.

Microscopic view on the polarization-resolved S-SHG intensity of the vapor/liquid interface of pure water.

Second harmonic generation (SHG) is a nonlinear optical phenomenon where two photons at the frequency ω combine to form a single photon at the second-harmonic frequency 2ω. Since that second-order process is very weak in bulk isotropic media, optical SHG responses of interfaces provide a powerful and versatile technique to probe the molecular structure and dynamics of liquid interfaces. Both local dipole contributions and non-local quadrupole contributions can be interesting to investigate different properties of the interface, such as the molecular orientation or the charge density. However, a major difficulty is to comprehend the link between the S-SHG intensity and molecular details. This article reports a numerical approach to model the polarization-resolved SHG intensities of a model vapor/liquid interface of pure water. The influence of the interfacial local environment on the hyperpolarizability is taken into account using quantum mechanical/molecular mechanics calculations. The numerical predictions are in very good agreement with experiments. We detail the hypotheses made during the modeling steps and discuss the impact of various factors on the modeled SHG intensities, including the description of the exciting field in the interfacial layer, the effect of neighboring molecules on the second-harmonic polarization, and the presence of an additional static electric field at the interface.

Dynamic tunable triple-band terahertz perfect absorber based on graphene metamaterial

This work developed a graphene-based perfect absorber with dynamic tuning capabilities. This absorber consists of a metal substrate, a layer of graphene square rings, a layer of graphene disks, and two layers of SiO2 dielectric sandwiched between them. Simulation results demonstrate absorption peaks at 1.23 THz, 4.2 THz, and 6.38 THz, with respective absorption rates of 99.9 %, 99.8 %, and 98.3 %. By analyzing the distributions of the electric field and surface current at the central frequencies of the three absorption peaks, the excitation mechanism of each absorption peak was discussed. It was found that by adjusting graphene's chemical potential, the absorption spectrum can be actively controlled. Furthermore, the absorber is insensitive to polarization and can sustain the stability of the absorption spectrum within an incident angle range of 0∼35°. This work has the potential to advance the research of multi-band terahertz absorbers, dynamically tunable devices, and other graphene-based photonic devices.

Facile modification of TiO2 as S-Scheme multifunctional materials for environmental protection and energy-storage applications

This paper reports a simple one-step modification of commercial TiO2 with a conducting polytrimethoxyslilypropyl aniline (PTMSPA, a polyaniline derivative having silyl networks) to have multi-functional (photocatalytic, optical, pseudocapacitive, hydrophobic, porous, antibacterial, and electromagnetic interference shielding (EMI)) properties and demonstrates associated applications. We present the S-Scheme heterojunction (SHJ) formation between TiO2 and PTMSPA through band position alignments and designate the resultant TiO2 - TiO2- based SHJ multifunctional materials as MF-TSSM. The internal electric field that is generated at the interface facilitates the transportation of the photogenerated electron transfer . The XRD pattern of MF-TSSM exhibits mainly the peaks of anatase TiO2. The TEM image of MF-TSSM indicates that the TiO2 particles are spherical in shape with sizes showing variations in diameters ranging from 60 nm to 250 nm depending on the experimental conditions of preparation and TiO2 particles are homogeneously distributed within the PTMSPA matrix. The optical energy band gap of MF-TSSM is 1.60 eV, a much lower value than PTMSPA (3.02 eV), suggesting that the composite formation between TiO2 and PTMSPA. The contact angle of MF-TSSM is significantly increased to 47.1 ° from 8.0 of TiO2, informing the increase of hydrophobic characteristics. The rate constant (k) for methylene blue photodegradation was 0.030 min-1, and 0.010 min-1 for MF-TSSM and pristine TiO2, respectively, The MF-TSSM composite exhibits a higher specific capacitance value (28.7 F/g) than TMSPA (21.1 F/g). At a frequency of 0.42 THz, MF-TSSM and PTMSPA exhibit return loss features indicating good EMI shielding performance. The MF-TSSM has been tested against two different Gram-positive and Gram-negative bacterial strains. The nanoparticles were evaluated at doses of 10, 20, 40, and 80 µg/ml. The results indicated that Klebsiella pneumoniae demonstrated a greater zone of inhibition, ranging from 9 mm at 10 µg/ml to 23 mm at 80 µg/ml, indicating increased susceptibility. Pseudomonas aeruginosa exhibited reduced inhibition zones, ranging from 10 mm at 10 µg/ml to 14 mm at 80 µg/ml, indicating increased resistance. The excellent effectiveness of MF-TSSM against various Gram-positive and Gram-negative pathogenic bacteria is explained by the interaction between reactive oxygen species and the cellular components of the bacteria as well the electrostatic interaction arising between positive charges in TMSPA and negative charges in the cell components, resulting in notable cytotoxicity and damage to the bacterial cells. The research underscores the capability of these modified TiO₂ nanoparticles in addressing bacterial infections, with efficiency differing by bacterial strain.

Low-field-driven large strain in lead zirconate titanium-based piezoceramics incorporating relaxor lead magnesium niobate for actuation

Studies on the piezoelectric materials capable of efficiently outputting high electrostrains at low electric fields are driven by the demand for precise actuation in a wide range of applications. Large electrostrains of piezoceramics in operation require high driving fields, which limits their practical application due to undesirable nonlinearities and high energy consumption. Herein, a strategy is developed to enhance the electrostrains of piezoceramics while maintaining low hysteresis by incorporating lead magnesium niobate relaxors into lead zirconate titanium at the morphotropic phase boundary. An ultrahigh inverse piezoelectric coefficient d33*\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${d}_{33}^{*}$$\\end{document} of 1380 pm/V with a reduced hysteresis of 11.5% is achieved under a low electric field of 1 kV/mm, outperforming the major lead-based piezoelectric materials. In situ synchrotron X-ray diffraction and domain wall dynamics characterization with sub-microsecond temporal resolution reveal that the outstanding performances originate from facilitated domain wall movement, which in turn is due to reduced lattice distortion and miniaturized domain structures. These findings not only address the pending challenges of effective actuation under reduced driving conditions but also lay the foundation for a more systematic approach to exploring the origin of large electrostrains.

The influence of the quasi-electrostatic support on the amplification of space charge waves in the amplification section of a superheterodyne free electron laser

Abstract In this work, a theoretical study of the influence of a quasi-electrostatic support on the amplification level of the slow space charge wave (SCW) in the amplification section of a superheterodyne free electron laser (FEL) was carried out. One of the ways to significantly increase the saturation level of the slow SCW is maintaining the conditions of a three-wave parametric resonance between the slow, fast SCWs and the resulting pump electric field. This can be done by introducing the quasi-electrostatic support in the superheterodyne FEL amplification section. Also, it was found that the generated pump electric field significantly influences the maintenance of parametric resonance conditions. As a result, this increases the saturation level of the slow SCW by 70%. Finally, the quasi-electrostatic support significantly reduces the maximum value of the electrostatic undulator pump field strength, which is necessary to achieve the maximum saturation level of the slow SCW.

Engineering of Interface Barrier in Hybrid MXene/GaN Heterostructures for Schottky Diode Applications.

The Fermi level position at the interface of a heterostructure is a critical factor for device functionality, strongly influenced by surface-related phenomena. In this study, contactless electroreflectance (CER) was utilized for the first time to investigate the built-in electric field in MXene/GaN structures with the goal of understanding the carrier transfer across the MXene/GaN interface. Five MXenes with high work functions were examined: Cr2C, Mo2C, V2C, V4C3, and Ti3C2. The physicochemical properties of the MXene/GaN structures were analyzed by using X-ray and UV photoelectron spectroscopies. It was shown that upon the coverage of the GaN surface by all investigated MXenes, a shift in the position of the surface Fermi level occurs, consequently raising the interface barrier. Additionally, the physicochemical stability of MXenes on the GaN surface was studied after annealing the structures at 750 °C. Our findings indicate that the annealing process increases the barrier height and the ionization energies of all studied structures. Furthermore, it has been shown that removing excess MXene material from the surface did not significantly impact the built-in electric field, emphasizing the robust physicochemical stability of the MXenes on the GaN surface. To validate the potential of engineering of MXene/GaN interface barrier, Schottky diodes with MXenes exhibiting the highest barrier height (Mo2C and V2C) were demonstrated.

Hollow Nanobox‐Shaped Cu2‐xS@ZnxCd1‐xS Heterojunction by Light Multireflection with Z‐Scheme Mechanism for Enhanced Photocatalytic Hydrogen Production

AbstractAchieving efficient spatial photoinduced charge separation and light utilization for improving the high photocatalytic activity is still a major obstacle. Here, a Cu2‐xS@ZnxCd1‐xS (Cu2‐xS@ZnCdS) heterojunction is reported featuring a distinctive core–shell hollow nanobox structure. The Cu2‐xS@ZnxCd1‐xS exhibits high photocatalytic activity in hydrogen evolution reaction (HER) at the rate of 8175 µmol∙g−1∙h−1 under visible light irradiation, outperforming pristine ZnCdS nanoparticles and Cu2‐xS hollow nanoboxes. The remarkable activity and outstanding stability of Cu2‐x@ZnCdS are attributed to the development of robust interfacial electric fields, and improved light multireflection absorption efficiency as well as the Z‐scheme mechanism. The electron paramagnetic resonance (EPR) and in situ X‐ray photoelectron spectroscopy (XPS) measurements gave the direct evidence of the formation of the Z‐scheme, which maintained the high redox potentials of each ZnCdS and Cu2‐xS. This study gives the guideline for the design of heterojunction with the Z‐scheme mechanism, leading to the high photocatalytic performance and remarkable stability.

Synthesis of in situ grown CNTs on MOF-derived Ni@CNT with tailorable microstructures toward regulation of electromagnetic wave absorption performance

Metal-Organic framework (MOF) derivatives have been applied as electromagnetic wave absorption (EMA) materials in recent years. Carbon nanotubes (CNTs) can achieve in situ growth on the surface of MOF derivatives. However, there is limited research on the EMA performance by regulating the morphology of the in situ grown CNTs. In this work, we prepared MOF-derived Ni@carbon nanotubes (Ni@CNT) with controllable length of CNTs by solvothermal and simple one-step pyrolysis method and revealed the CNT growth mechanism. We further investigated the effect of in situ grown CNT morphology on electromagnetic parameters and EMA performance. In situ grown CNTs of similar length on the surface of MOF derivatives lead to similar electromagnetic parameters. When the length of CNTs is short, the relaxation strength (Δε=εs−ε∞) is high, leading to excellent microwave absorption performance. For Ni@CNT-600, the reflection loss of −44.4 dB can be achieved at merely 1.72 mm. Finite element (FE) simulation was used to evaluate the EMA mechanism of different samples by calculating electric field and polarization strength. This work has explored the electromagnetic wave absorption performance from the perspective of microstructural tailoring, helpful for understanding the unique role of the in situ grown CNTs on the surface of MOF derivatives and investigating the ultra-thin electromagnetic wave absorption materials.

U-AEFA: Online and offline learning-based unified artificial electric field algorithm for real parameter optimization

Optimization problems in real-world scenarios require algorithms that effectively balance exploration and exploitation to avoid local optima and achieve global solutions. To address this, we propose a unified artificial electric field algorithm (U-AEFA) that integrates both offline learning (inspired by high-performing metaheuristic algorithms) and online learning (through historical data generated during evolution). U-AEFA introduces a unique three-layer population structure to enhance search efficiency, consisting of the best agent in the first layer, the top-performing agents in the second layer, and the remaining agents in the third layer. Key features of U-AEFA include (i) an effective Coulomb’s constant for improved exploration, (ii) a non-uniform mutation operator to mitigate premature convergence, and (iii) two acceleration coefficients for enhanced performance. These three factors constitute offline learning and have been implemented to improve different design elements of the algorithm. As part of online learning, it employs a difference vector reuse (DVR) strategy to evolve the first-layer agents. The algorithm is evaluated using the CEC 2017 test suite across multiple dimensions (10, 30, 50, 100), where it consistently outperforms seven state-of-the-art algorithms, demonstrating superior accuracy and convergence speed. Moreover, U-AEFA’s robustness is validated on 12 high-dimensional feature selection problems, further highlighting its effectiveness in solving complex optimization tasks. The source code of U-AEFA is available at

Capacity recovery by transient voltage pulse in silicon-anode batteries.

In the quest for high-capacity battery electrodes, addressing capacity loss attributed to isolated active materials remains a challenge. We developed an approach to substantially recover the isolated active materials in silicon electrodes and used a voltage pulse to reconnect the isolated lithium-silicon (LixSi) particles back to the conductive network. Using a 5-second pulse, we achieved >30% of capacity recovery in both Li-Si and Si-lithium iron phosphate (Si-LFP) batteries. The recovered capacity sustains and replicates through multiple pulses, providing a constant capacity advantage. We validated the recovery mechanism as the movement of the neutral isolated LixSi particles under a localized nonuniform electric field, a phenomenon known as dielectrophoresis.

Construction of Al/Ti₃C₂Tₓ composites via electrostatic self–assembly for visible–infrared camouflage applications

Attaining the equilibrium of subdued luminance, low visible light reflectance, and high infrared reflectance constitutes a formidable challenge in the realm of visible–infrared camouflage. Here, an electrostatic self–assembly method was proposed to fabricate the Al/Ti₃C₂Tₓ (AT) composite. The synergy between Ti3C2Tx’s favorable optical properties and significant conductivity of Al powder grants the AT composite excellent visible–infrared camouflage capabilities. At a mass ratio of 4:1 for Al powder to Ti3C2Tx (AT–4), the composite displays a gray coloration, achieving a 40 % reduction in visible light reflectance and an emissivity value of 0.28. Such properties enable the AT–4 composite to effectively blend into various thermal environments, showcasing its superior infrared camouflage capabilities. Additionally, incorporating Ti3C2Tx layers significantly boosts the local electric field in the composite, enhancing photon–material interactions and consequently reducing its visible light reflectance. This work offers valuable insights for the development of advanced materials with integrated visible–infrared camouflage capabilities.

The degradation mechanism of high power S-band AlGaN/GaN HEMTs under high temperature

Abstract The radio frequency (RF) degradation mechanism under high temperature is proposed in this paper. The saturated output power (P sat), power added efficiency (PAE) and gain of the HEMTs deteriorate significantly under high power dissipation operation conditions, which contribute to an elevation of the junction temperature (T j). The high T j causes a negative shift of the threshold voltage and a reduction of electron mobility, as well as enhancing the trapping effects of the devices. As a result, the P sat and PAE of the high-power HEMTs (P sat = 152 W) decreased by 0.76 dB and 8.3%, respectively, which is more severe compared to low-power HEMTs (P sat = 20 W), where P sat and PAE reduced by 0.16 dB and 3.1% when the operation temperature was increased from 25 °C to 150 °C. By increasing the gate-to-drain distance from 1.625 to 2.175 μm, drain current stability and high temperature reverse bias reliability are improved. The results demonstrate that the trapping effect can be suppressed by decreasing the electric field under the gate; therefore, the RF output characteristics are boosted by 1.2 W, 1 dB and 2.6% for a device with gate width of 11.52 mm.