Output Current Increases Research Articles

Improvement of Electron Transport Property and on-Resistance in Normally-OFF Al₂O₃/AlGaN/GaN MOS-HEMTs Using Post-Etch Surface Treatment

Post-etch surface treatment technique was developed for normally-OFF recess-gate Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> /AlGaN/GaN metal-oxide-semiconductor high-electron-mobility transistors (MOS-HEMTs). By removing the residues and smoothing surface morphology after plasma etch, the diffusion-controlled interface oxidation (DCIO) and wet etch in MOS-HEMTs lead to a decrease in interface traps from 1.04 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">12</sup> to 6.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> with a filling voltage of 12 V. Field-effect mobility extracted in the linear region is 48 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> /V · s for MOS-HEMTs with an optimized post-etch surface treatment process, 33% larger than the case with the conventional chemical clean process. Due to the increased electron mobility and decreased sheet resistance beneath the gate by over 30%, normally-OFF MOS-HEMTs with DCIO and wet etch exhibit a remarkable increase in output current by about 29% and an increase in peak transconductance from 35 to 41 mS/mm. The optimized post-etch surface treatment method also enhances blocking voltage from 120 to 230 V by suppressing the leakage current resulting from gate soft breakdown. Dynamic characterization shows that the normalized ON-resistance is increased by double with drain stress up to 80 V, and various post-etch surface treatment processes have little effect on current collapse. Two types of threshold voltage shifts caused by interface trapping and border trapping are observed in the normally-OFF MOS-HEMTs, which keeps stable with an increase in temperature up to 125 °C.

Modulation of the two-dimensional electron gas channel in flexible AlGaN/GaN high-electron-mobility transistors by mechanical bending

We investigate the effect of strain on the two-dimensional electron gas (2DEG) channel in a flexible Al0.25Ga0.75N/GaN high-electron-mobility transistor (HEMT) by mechanical bending to prove the concept of active polarization engineering to create multifunctional electronic and photonic devices made of flexible group III-nitride thin films. The flexible HEMTs are fabricated by a layer-transfer process and integrated with a 150-μm-thick Cu film. The strain values are estimated from high-resolution x-ray diffraction and Raman spectroscopy in 4-cm bend-down and −4-cm bend-up test conditions. The strain-induced piezoelectric polarization can alter the charge density of the 2DEG in the channel at the AlGaN/GaN interface and thus modify the output characteristics of the flexible HEMTs. Accordingly, output characteristics show an increase in output current by 3.4% in the bend-down condition and a decrease by 4.3% in the bend-up condition. Transfer characteristics show a shift of threshold voltage, which also supports the 2DEG channel modulation during bending. Computational simulation based on the same structure confirms the same current modulation effect and threshold voltage shift. Furthermore, the electrical characteristics of the flexible HEMTs show a repeatable dependence on the strain effect, which offers potential for electro-mechanical device applications.

Effects of Low-Damage Plasma Treatment on the Channel 2DEG and Device Characteristics of AlGaN/GaN HEMTs**Supported by the National Natural Science Foundation of China under Grant Nos. 61634005, 61704124, and 11690042.

We investigate the effects of remote nitride-based plasma treatment on the channel carrier and device characteristics of AlGaN/GaN high electron mobility transistors (HEMTs). A 200 W NH3/N2 remote plasma causes little degeneration of carrier mobility and an increase in electron density due to surface alteration, which results in a decrease in sheet resistance and an increase in output current by 20–30%. Improved current slump, suppressed gate leakage current, and improved Schottky contact properties are also achieved by using low-damage nitride-based plasma treatment. It is found that NH3/N2 remote plasma treatment is a promising technique for GaN-based HEMTs to modulate the surface conditions and channel properties.

Active Porous Electrodes Prepared by Ultrasonic‐bath and their Application in Glucose/O2 Electrochemical Reactions

AbstractMost of the practical applications in electrocatalysis require porous electrodes, built by dispersing the nanoparticles (NPs) on a gas diffusion layer, as carbon paper (CP). The lack of correlation between classic measurements in clean, controlled surfaces and thin films with those of porous electrodes, used in practical application, is largely neglected. Since catalysis depends on the area available, it is clear that the distribution of the NPs on the porous material is pivotal to the efficiency of the catalyst. Here we show a low‐cost method to disperse NPs on CP assisted in ultrasonic bath. Such method improves the Pt/C NPs distribution over the CP compared to the immersion method. As proof‐of‐concept, we show an increase in output current by using Pt/C/CP for 10 mM glucose electrooxidation and O2 eletroreduction in buffered solution at 37 °C, which is ascribed to the increase in collision factor. Furthermore, the cathodic reaction is facilitated compared to electrodes prepared by immersion, yielding an unprecedented open circuit voltage of 800 mV for the coupled reaction. The glucose/oxygen reaction is also investigated in passive flow in an H‐type cell to produce power. This concept shows promising application to build any kind of porous electrodes with improved area utilization.

A Green Triboelectric Nano-Generator Composite of Degradable Cellulose, Piezoelectric Polymers of PVDF/PA6, and Nanoparticles of BaTiO3.

In this paper, a kind of green triboelectric nano-generator based on natural degradable cellulose is proposed. Different kinds of regenerated cellulose composite layers are prepared by a blending doping method, and then assembled with poly(tetrafluoroethylene) (PTFE) thin films to form tribioelectric nanogenerator (TENG). The results show that the open circuit output voltage and the short circuit output current using a pure cellulose membrane is 7.925 V and 1.095 μA. After adding a certain amount of polyamide (PA6)/polyvinylidene fluoride (PVDF)/barium titanate (BaTiO3), the open circuit output voltage peak and the peak short circuit output current increases by 254.43% (to 20.155 V) and 548.04% (to 6.001 μA). The surface morphology, elemental composition and functional group of different cellulose layers are characterized by Scanning Electronic Microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and tested by the electrochemical analyze. Moreover, after multiple assembly and rectification processing, the electrical output performance shows that the peak value of open-circuit output voltage and the peak value of short circuit output current increases by 132.06% and 116.13%. Within 500 s of the charge-discharge test, the single peak charge reached 3.114 V, and the two peak charges reached 3.840 V. The results demonstrate that the nano-generator based on cellulose showed good stability and reliability, and the application and development of natural biomaterials represented by cellulose are greatly promoted in miniature electronic sensing area.

Study on higher output current of automotive rotary electric machine

In recent years, motor generators have been required to further reduce size, light weight, higher output current and higher efficiency, due to strengthening exhaust gas regulation and new fuel efficiency standards in each country and to increasing number of on-vehicle electrical components. In order to increase the output current and reduce the noise of motor generators, we examined the increase in output current by improving the cooling performance of the field coil. It was clarified that by providing cooling holes in the main plate of the cooling fan, it is possible to achieve both increase in output current and reduction in noise.

Optoelectronic CMOS Transistors: Performance Advantages for Sub-7nm ULSI, RF ASIC, Memories, and Power MOSFETs

AbstractSubstantial increase of output current, and Ion / Ioff ratio for sub-7nm low power CMOS transistors, can be accomplished using a novel optoelectronic technology, which is 100% compatible with existing CMOS process flow. For RF or mixed signal ASICs, adding photonic components may improve the cut-off frequency, and reduce series resistance. Products that utilize power regulating devices, such as power MOSFETs, will benefit from the optoelectronic configuration to achieve much lower Rdson and high voltage at the same time. For semiconductor memories, such as DRAM or FLASH, the photonic technique may reduce the ERASE / WRITE / access time and improve the reliability.

Investigation of Nonlinear Droop Control in DC Power Distribution Systems: Load Sharing, Voltage Regulation, Efficiency, and Stability

Linear droop faces the design tradeoff between voltage regulation and load sharing due to cable resistances and sensing errors. Using a larger droop resistance improves load sharing, but requires a wider droop voltage range. In the nonlinear droop, droop resistance is a function of the converter's output current, and its value increases when the output current increases. As a result, the impacts from sensors and cables are reduced. In this paper, the design of nonlinear droop in dc power distribution systems is studied with special emphasis on load sharing, voltage regulation, system efficiency, and stability. After discussing the piecewise linear and nonlinear droop control, a generic polynomial expression is presented to unify different droop equations. The impact of droop on dc system efficiency is analyzed by evaluating cable and power converter losses. The converter's output impedance using nonlinear droop is modeled to analyze the system stability with constant power loads. The selection and design guidelines of nonlinear droop are summarized, considering both the static performance and interaction with load systems. The analysis is verified in 400-V multi-source dc systems. The nonlinear droop is fully distributed as it only needs local information.

DC–DC Boost Converter With a Wide Input Range and High Voltage Gain for Fuel Cell Vehicles

In fuel cell vehicles, the output voltage of the fuel cell source is typically much lower than the voltage required by the dc bus, and also this output voltage drops significantly as the output current increases. In order to match the output voltage of the fuel cell source to the dc bus voltage, a new dc–dc boost converter with a wide input range and high voltage gain is proposed to act as the required power interface, which reduces voltage stress across the power devices and operates with an acceptable conversion efficiency. A prototype rated at 300 W/400 V has been developed and the maximum efficiency of the proposed converter was measured as 95.01% at 300 W. Experimental results are presented to validate the effectiveness of the proposed converter.

A Planar Distributed Channel AlGaN/GaN HEMT Technology

This brief presents AlGaN/GaN high electron mobility transistor (HEMT) devices with improved thermal and dc current–voltage ( ${I}$ – ${V}$ ) performance using a novel method of obtaining a distributed channel device, i.e., the total semiconductor area between the ohmic contacts comprise conducting and nonconducting regions. A novel oxygen (O2) plasma treatment technique is used to realize the inactive or nonconducting regions. Multifinger devices with 1-mm gate periphery exhibit extremely low gate leakage currents below $0.2~\mu \text{A}$ /mm at a gate voltage of −20 V and an increase in the saturated output current by 14% at 20-V drain voltage. Moreover, performed dc ${I}$ – ${V}$ measurements at various ambient temperatures show that the proposed method not only increases the saturated output currents by over 10% for ${1} \times {100}\,\,\mu \text{m}^{{2}}$ gate devices but also significantly reduces their knee walkout voltage from 6 to 3 V at 300 K. These results show that this device design approach can exploit further the potential of the GaN material system for transistor applications.

Опыт использования протонной лучевой терапии в объединенном институте ядерных исследований, г. Дубна

First experiments on using proton beams for radiotherapy of malignant tumours at the 680 MeV proton synchrocyclotron of the V.P. Dzhelepov Laboratory of Nuclear Problems of the Joint Institute for Nuclear Research (DLNP JINR) have been initiated by Prof. V.P. Dzhelepov and were started in 1967. 28 patients with different types of superficially located malignancies, such as skin melanomas, metastases of cancer to peripheral nodes, larynx cancers and so on, were treated during the period of 1967–1971. Then the method of scanning rotation irradiation of deep-seated tumours was developed and started to use at DLNP JINR. 50 patients with esophagus cancer, larynx cancer and metastases of malignant tumors were treated with that technique. During the period of 1974–1984 the synchrocyclotron was modified to the Phasotron with the increase of output current. At the same time, a multi-room Medico-technical complex for hadron radiotherapy of cancer patients was constructed. It allows tumour treatment with wide and narrow horizontal beams of protons (70–660 MeV), negative pions (30–80 MeV), high-energy neutrons (mean energy 350 MeV), and with their combinations. The complex includes also the standard gamma-therapy unite Rokus-M with 60Co source for external irradiation. The unique equipment has been developed and constructed, including full-scale PET, X-ray CT for topometry of patients in sitting position, and proton CT. A new round of the development started in December 1999 when a specialized radiological department of patient capacity of 25 beds was opened in Dubna. Since 2000 regular sessions have been conducted in research of proton therapy efficiency in irradiation of patients with neoplasms located in the head, neck and other parts of the body. 1283 patients have received courses of radiotherapy at the Phasotron beams by the end of 2018. The technique of 3D conformal proton radiotherapy in which the maximum of the formed dose distribution conforms most accurately to the shape of the irradiated target has been realized and put into operation. In this way, the maximum sparing effect is achieved in normal tissues and organs surrounding the tumor. The statistical analysis of the proton treatment results of two classes of neoplasms treated with the JINR proton beam (arteriovenous malformation) of the brain and the skull base chordomas and chondrosarcomas) are presented. A new project of the development and construction of a modern superconducting cyclotron SC202 dedicated for proton radiotherapy was prepared recently by the staff of the DLNP JINR and Institute of Plasma Physics Chinese Academy of Sciences (Hefei, China). It is supposed that the accelerator will become the base of a new Proton Therapy Centre in Dubna. It will consist of two treatment rooms: the first one will be equipped with static wide horizontal proton beam and a therapeutic chair, and the second one is planned to provide with gantry for a pencil proton beam dynamic scanning and a positioner for supine patient position during irradiation.

Particle-In-Cell Simulation on the Multipacting Process of a Novel High-Current Density Cathode

The configuration design of a novel high-current density cathode for producing a ring-like electron beam is briefly introduced. Due to the complicated physical process of this novel cathode, in this paper, only the temporal evolution of multipacting on this cathode surface is numerically simulated by using the particle-in-cell method. The simulation results indicate that the multipacting process could be successfully achieved on the surface of this cathode. In multipacting process, both the electron number and output current start rapid exponential increases in very short time and then tend to be saturation with slow decreases. The multipacting start point is not at the triple-junction (vacuum-metal-dielectric) region but has a distance to the region. The saturation region of multipacting will expand toward the outlet with the spreading speed on the order of 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> m/s, which agrees with the speed of the luminous front of the initial surface flashover measured by experiment, and the emission current density of the cathode could reach the level of kA/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> . The region of multipacting electrons will first be lengthened and then will be shortened due to the region of deposited positive charges expanding to the outlet and the maximum value of deposited positive charges moving from the triple-junction region to the outlet side.

Power loss analysis of current-modules based multilevel current-source power inverters

A power loss analysis of multilevel current-source inverter (MCSI) circuits developed from two basic configurations of three-level current-source inverters, i.e. H-bridge and common-emitter inverter configurations is presented and discussed. The first circuit topology of the MCSI is developed by using DC current modules connected to the primary three-level H-bridge inverter. The second MCSI circuit is created by connecting the current-modules to a three-level common-emitter inverter. The DC current modules work generating the intermediate level waveform of the inverter circuits. Power loss analysis of the both topologies was carried out to explore the efficiency performance of the inverter circuits. The results showed that for the H-bridge and common-emitter MCSI using DC current modules, the amount of conduction losses in the inverter circuits could be diminished when the level number of AC output current increase. The measurement test results have also proved that using these MCSI topologies, the power conversion efficiency will also increase.

Microsensor for limonin detection: An indicator of citrus greening disease

Limonin is a biomolecule which is responsible for the bitter taste in citrus fruits such as oranges, grapes etc. The abnormally high level of limonin is indicative of citrus greening disease which results in stunted tree growth and affects fruit quality in terms of nutritional value, taste, texture and aroma. Therefore, quantification and detection of limonin is crucial for an early management of citrus greening disease to save the multibillion dollar citrus industry. To this end, an organic electrochemical transistor (OECT) functionalized with Ceria Nanoparticles (CNPs) as transducer has been developed to detect ultralow concentration of limonin. The device exhibited high sensitivity (detection limit: 10 nM) and selectivity towards limonin with response time in seconds. The detection is attributed to the switching of Ce3+ to Ce4+ at the gate electrode which decreases the overall effective gate voltage resulting in an increase in the output current. The increase in output current was observed in transfer characteristics as well as time-current curve. In-situ spectro-electrochemical studies were also performed to analyse the change in oxidation state of CNPs in the presence of limonin. This novel biosensor successfully detected the increase in limonin in infected juice samples as compared to healthy ones with a sensitivity of ∼10 μA/μM. A rapid, easy and on-site testing tool to detect and quantify the amount of limonin for an early detection of citrus greening disease has been demonstrated for the first time.

Effect of Chirality and Oxide Thikness on the Performance of a Ballistic CNTFET

&lt;p&gt;Since the discovery of 1D nano-object, they are constantly revealing significant physical properties. In this regard, carbon nanotube (CNT) is considered as a promising candidate for application in future nanoelectronics devices like carbon nanotube field effect transistor (CNTFET). In this work, the impact of chirality and gate oxide thikness on the electrical characteristics of a CNTFET are studied. The chiralities used are (5, 0), (10, 0), (19, 0), (26, 0), and the gate oxide thikness varied from 1 to 5 nm.This work is based on a numerical simulation program based on surface potential model. CNTFET Modeling is useful for semiconductor industries for nano scale devices manufacturing. From our results we have observed that the output current increases with chirality increasing.We have also highlight the importance of the gate oxide thickness on the drain current that increases when gate oxide is thin.&lt;/p&gt;

Cryogenic R5912-20Mod photomultiplier tube characterization for the ProtoDUNE dual phase detector

The Deep Underground Neutrino Experiment (DUNE) is a dual-site experiment for long-baseline neutrino oscillation studies, and for neutrino astrophysics and nucleon decay searches. The far detector is a 40-kton underground liquid argon time-projection-chamber (LAr TPC), in which the photon detector system adds precise timing capabilities. The ProtoDUNE Dual-Phase detector will consist of a 6×6×6 m3 LAr TPC to be operated at the CERN Neutrino Platform and the photon detection system will be formed by 8-inch cryogenic photomultipliers from Hamamatsu. The PMT model (R5912-20Mod) performance at cryogenic temperature is studied including dark current, gain, and linearity with the light intensity and pulse rate. In addition, the PMT base design is validated. At cold, a decrease of the PMT amplification, or fatigue effect, is measured as the PMT output current increases, either, due to high gain, light intensity or rate. Also, the characterization results of the 40 photomultipliers to be used in ProtoDUNE Dual-Phase are presented.

Au nanocomposite enhanced electret film for triboelectric nanogenerator

A triboelectric nanogenerator (TENG) with an organic nanocomposite electret thin film as the triboelectric layer for mechanical energy harvesting was investigated systematically. In combination with corona charging, a TENG was fabricated by using embedded-nanocapacitor-structure polytetrafluoroethylene (PTFE) impregnated with gold nanoparticles (Au-NPs). The output performances, stability, and durability of the TENGs with Au-PTFE nanocomposite films were characterized after being washed in water. It was found that the output current increases by 70% and the equivalent surface charge density (ESCD) reaches 85 μC/m2 in comparison to the virgin PTFE film. Such outstanding performance is likely due to the equivalent nanocapacitors between the Au-NPs and PTFE molecules, which serve as nano charge traps in the nanocomposite electret film under negative high-voltage corona charging. This work not only expands the practical applications of TENGs, but also opens up new possibilities for the development of high performance triboelectric materials.

Monolithic acoustic graphene transistors based on lithium niobate thin film

This paper introduces an on-chip acoustic graphene transistor based on lithium niobate thin film. The graphene transistor is embedded in a microelectromechanical systems (MEMS) acoustic wave device, and surface acoustic waves generated by the resonator induce a macroscopic current in the graphene due to the acousto-electric (AE) effect. The acoustic resonator and the graphene share the lithium niobate film, and a gate voltage is applied through the back side of the silicon substrate. The AE current induced by the Rayleigh and Sezawa modes was investigated, and the transistor outputs a larger current in the Rayleigh mode because of a larger coupling to velocity ratio. The output current increases linearly with the input radiofrequency power and can be effectively modulated by the gate voltage. The acoustic graphene transistor realized a five-fold enhancement in the output current at an optimum gate voltage, outperforming its counterpart with a DC input. The acoustic graphene transistor demonstrates a paradigm for more-than-Moore technology. By combining the benefits of MEMS and graphene circuits, it opens an avenue for various system-on-chip applications.

Review on various strategies for maximum efficiency of solar panels

Solar modules are used to convert sunlight directly into electric current. Certain parameters of the module decreases the overall efficiency of the module. These parameters include temperature, soiling, tilt angle. As the temperature increases the output current increases exponentially voltage decreases linearly. To overcome these problems simple,robust,cheap techniques are used to increase overall efficiency of the module.These techniques include MPPT,temperature control, nanowire solar cells and varying tilt angle in summer and winter seasons.

Effect of depositing PCBM on perovskite-based metal–oxide–semiconductor field effect transistors**Project supported by the National Natural Science Foundation of China (Grant No. 51602241) and the China Postdoctoral Science Foundation (Grant No. 2016M592754).

In this manuscript, the perovskite-based metal–oxide–semiconductor field effect transistors (MOSFETs) with phenyl-C61-butyric acid methylester (PCBM) layers are studied. The MOSFETs are fabricated on perovskites, and characterized by photoluminescence spectra (PL), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). With PCBM layers, the current–voltage hysteresis phenomenon is effetely inhibited, and both the transfer and output current values increase. The band energy diagrams are proposed, which indicate that the electrons are transferred into the PCBM layer, resulting in the increase of photocurrent. The electron mobility and hole mobility are extracted from the transfer curves, which are about one order of magnitude as large as those of PCBM deposited, which is the reason why the electrons are transferred into the PCBM layer and the holes are still in the perovskites, and the effects of ionized impurity scattering on carrier transport become smaller.