X-Band GaN Power HEMTs with Power Density of 2.23 W/mm Grown on Sapphire by MOCVD

The growth, fabrication, and characterization of 0. 2μm gate-length AlGaN/GaN HEMTs, with a high mobility GaN thin layer as a channel,grown on （0001） sapphire substrates by MOCVD,are described. The unintentionally doped 2.5μm thick GaN epilayers grown with the same conditions as the GaN channel have a room temperature electron mobility of 741cmz^2（V· s） at an electron concentration of 1.52 × 10^16 cm^-3. The resistivity of the thick GaN buffer layer is greater than 10^8Ω· cm at room temperature. The 50mm HEMT wafers grown on sapphire substrates show an average sheet resistance of 440.9Ω□ with uniformity better than 96%. Devices of 0.2μm× 40μm gate periphery exhibit a maximum extrinsic transconductance of 250mS/mm and a current gain cutoff frequency of 77GHz. The AlGaN/GaN HEMTs with 0.8mm gate width display a total output power of 1.78W （2.23W/mm） and a linear gain of 13.3dB at 8GHz. The power devices also show a saturated current density as high as 1.07A/mm at a gate bias of 0.5V.

HH—聚氨酯透明灌封胶的研究

HH—聚氨酯(PU)透明灌封胶是由多种聚醚预聚体、固化剂和催化剂组成的双组份胶液,主要应用于印制线路板等电子元器件组合的灌封,以提高电子、电气产品的绝缘性和耐振动、高低温、湿气、霉菌,以及抗加速冲击的能力。该胶具有优良的电性能与附着力,透明性好,能在70℃以下固化,当元器件发生故障时也能切除、修复。经过四年来在军用电子产品上的应用证明,性能稳定、可靠,工艺性好,成本也低,可代替传统的有机硅凝胶。

A new chlorinated non-fullerene acceptor based organic photovoltaic cells over 12%efficiency

The method to fluorinate the terminal group has achieved remarkable success and been widely used to fine-tune the intrinsic properties of organic acceptor materials.Referring to chlorination,however,it gets less attention and remains ambiguous effect on organic photovoltaic(OPV)cells.Herein,a new non-fullerene acceptor named Y19 was reported with benzotriazole as the electron-deficient core and 2Cl-ICs as the strong electron-withdrawing end groups.Y19 exhibits a wide film absorption band from 600 nm to 948 nm and low LUMO(the lowest unoccupied molecular orbital)energy level of−3.95 eV.Photovoltaic devices based on PM6:Y19 show high-power conversion efficiency(PCE)of 12.76%with high open-circuit voltage(Voc)of 0.84 V,short-circuit current density(Jsc)of 22.38 mA/cm2 and fill factor(FF)of 68.18%.Broad external quantum efficiency(EQE)response of over 60%in the range of 480−860 nm can be obtained.This study demonstrates that chlorination,as a low-cost molecular design strategy,has its own superiorities to improve device performance and promote the potential application in OPV.

Recent Achievement of Gas Electron Multiplier

Gas electron multiplier (GEM) as a novel gas detector,due to it’s simple structure,high performance,well compatibility etc.,is widely used in high-energy physics,nuclear physics and other fields.In this review,the principle,recent achievements,developments and applications of GEM are mainly described.

The role of the symmetry and the flexibility of the anion on the characteristics of the nanostructures and the viscosities of ionic liquids

The transport properties of ionic liquids(ILs) are crucial properties in view of their applications in electrochemical devices. One of the most important advantages of ILs is that their chemical–physical properties and consequently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the "rigidity", the order,and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be controlled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion.

Multielectrode Semiconductor Lasers

Multielectrode semiconductor lasers are studied via the ray method.The expression of the output photon number of N -electrode semiconductor lasers has been derived for the first time.When N =1 or 2,the expression of the output photon number fits in that of one-electrode (general) or two-electrode semiconductor lasers perfectly.

Energy Spectrum of La3Lu2Ga3O12：Cr^3＋ and Its Pressure-Induced R-Line-Shift Reversal

By means of both the theory for pressure-induced Shifts （PS） of energy spectra and the theory for shifts of energy spectra due to electron-phonon interaction （EPI）, the normal-pressure energy spectra of α and β centers of Cr^3＋ ions for LLGG：Cr^3＋ and the PS＇s of R1 lines and U band of these centers have been calculated at 10 K, respectively. The total calculated results are in very good agreement with the experimental data. For LLGG：Cr^3＋, the pressureinduced low-high crystal-field transition and the reversal of R1-line PS take place. The pressure-dependent variation of Rmix^ei （2E - 4T2） [mixing-degree of （t2^2 （^3T1）e^4T2） and （t2^3 E） base-wavefunctions in the wavefunction of R1 state without EPI] plays a key role for the reversal of R1-line PS. The behavior of the pure electronic PS of R1 line is quite different from that of the PS of R1 line due to EPI. It is the combined effect of them that gives rise to the total PS of R1 line. The comparison between R1-line PS＇s of GSGG：Cr^3＋ and LLGG：Cr^3＋ has been made. It is found that a peak of R1-line PS appears at Rmix^ei （^2E - ^4T2） ≈ 0.08.

Corrosion detection of tinplate cans containing coffee using EIS/EN sensor

The corrosion behavior of tinplate cans containing coffee was investigated using novel electrochemical impedance spectroscopy(EIS) and electrochemical noise(EN) sensors.The contents of iron and tin dissolved in cans were detected by inductively coupled plasma mass spectrometer(ICP-MS),and the morphology of corroded surface was observed by optical microscopy and scanning probe microscopy(SPM).The results reveal that the coating resistance,charge transfer resistance and noise resistance decrease with the prolongation of storage time.The iron and tin contents in cans increase with the storage time,while the bump height of coating surface increases from 30 nm to 80 nm during the corrosion of twelve months.The existence of deformation would enhance the corrosion process of tinplate cans.Finally,the corrosion mechanism of tinplate cans in coffee was proposed.

Detection of Photons and Electrons Using a Semiconductor Alpha Detector

The response of a silicon alpha detector to beta particles, electrons and photons was investigated using measurements and Monte Carlo simulations. This information is of relevance for in situ alpha spectrometry from different surfaces at ambient air pressure. According to the simulations, photon detection efficiencies were more than two orders of magnitude smaller than those of electrons. Photons generate signals mainly by Compton electrons. Counts originating from beta particles, electrons and photons were usually below 1 MeV in energy and no clear peaks could be identified from the measured spectra. Unequivocal identification of radionuclides emitting beta particles, electrons and photons is not possible when a mixture of different radionuclides is present in the source. However, radionuclide classification according to their emission energies appears to be possible. Surface contamination measurements will benefit from this capability.

System design of a dexterous lightweight robot arm with remote control

This paper presents a novel remote controlled dexterous robot arm with 6 degrees of freedom （DOF）. As a highly integrated mechatronics system, sensors and their signal processing system are integrated inside each joint. To lighten the weight, almost all mechanical parts are made of aluminum and the robot control system is placed outside. The modular concept is adopted during the robot design process for time and cost saving. Considering the much greater torque acted on the two shoulder joints, the joint shells are strengthened in the design to increase joint stiffness and suppress system vibration. Meanwhile, to simplify the maintenance, a new spring pins electronic connector is designed to disassemble every joint, connector and link independently without cutting any cables. The teleoperation technology enables the robot to offer more convenient service definitely for people＇ s daily life. Virtual reality technology is used to solve the time delay problem during teleoperation. Finally, two typical daily chore experiments are implemented to prove the manipulation ability of the dexterous robot arm.

Non-local Consciousness Influence to Physical Sensors： Experimental Data

Experimental approach to investigation of NLCI （Non-local Consciousness Influence） effects is based on sensors of different design, and most of it based on transitional effects in gas-discharge plasma with several quasi-stable states is also presented. Computerized device for detecting NLCI is based on commercially available Gas Discharge Camera （www.ktispb.ru） and allows following time dynamics of several sensors in NLCI conditions. The typical sensors are： water, air, earth, and wood, this instrument was named ＂The 5th Element＂. Readings are taken continuously by special software every five or ten seconds in automatic mode. Sensitivity of the device was tested by detecting the influence of total sun eclipse in Siberia in 2008 and by detecting sunrise and sunset. Several experimental modalities have been developed： （1） directed NLCI of a person; （2） directed NLCI of a group of people; and （3） non-directed NLCI of a group of people. Experiments during many years demonstrated efficiency of the developed approach.

High Power Density Three-Level Three-Phase AC-DC 48 V Power Supply

International standards impose several constraints concerning the electric power quality and require that the harmonic content of the line current of grid connected equipment is below assigned limits; for this reason, operating of AC-DC converters with high power factor and low line current distortion has become essential. In this paper, the prototypal realization of a three-phase AC-DC 48 V power electronic converter for telecom system supplying is described and experimental testing results are discussed. The main constraints in the power supply design are the required power density of about 900 W per dm3 as well as the absence of the neutral wire in the supply grid. The carried out investigation is focused on three-level power converter configurations which are considered in order to reduce voltage rating of power switches. As a result of the reduced voltage, low on-resistance metal-oxide-semiconductor field effect transistors can be used in the power stage, solution which allows to achieve improved efficiency as well as increased switching frequency with respect to the insulated gate bipolar transistors based two-level topologies.

Low phase noise millimeter wave monolithic integrated phase locked-loop

A Monolithic integrated phase locked-loop （PLL） with a low phase noise is proposed in this paper. Several techniques are utilized to improve the performance of the PLL which works at the milli- meter-wave band. The on-chip high-Q eoplanar waveguides （CPWs） are utilized in the resonant tank and the differential current amplifier with a resonator is used to realize the VCO. In the output buffer circuit, several stages of cascaded source-followers connect and differential amplifiers are adopted to improve the driving capability of the PLL＇ s output signals. An improved analog multiplier topology is also used in the PD circuit to improve the gain of the PD. The proposed PLL is realized with a 0.2p, m GaAs pseudomorphie high electron mobility transistor （PHEMT） process. At 10 kHz offset from the center frequency, the measured output phase noise of the PLL output is only -88.83dBc/Hz. The circuit exhibits a low root mean sauare （RMS） litter of 1.68Ds.

High-Performance AC-DC Power Electronic Converter Generator for Hybrid-Solar Vehicles

This paper describes the principles of operation and the physical model of an advanced AC-DC converter generator （with the electronic converter acting as an AC-DC rectifier with reverse-conducting MOSFETs （metal-oxide semiconductor field-effect transistors） as fast-electronic switches with a relatively low ON-state voltage drop） for HSVs. An AC-DC converter, when seen as an AC-DC rectifier, can be used in many fields, e.g., for multi-functional AC-DC/DC-AC convener generator^starter and conventional DC-AC convener motors and AC-DC converter generators or generator sets, welding machines, etc. The paper also describes a novel AC-DC convener, with reverse-conducting transistors and without the use of optoelectronic separation （which does not require a separate power supply）, which may be easily realized in IC （integrated-circuit） technology. Computer simulation allows for waveform evaluation for timing analysis of all components of the AC-DC-converter＇s physical model, both during normal operation as well as in some states of emergency. The paper also presents the results of bench experimental studies where the MOSFETs were used as fast-electronic switches with a relatively low ON-state voltage drop. For experimental studies, a novel AC-DC converter has been put together on the Mitsubishi FM600TU-3A module. The AC-DC converter with reverse-conducting transistors in a double-way connection has a lot of advantages compared to the conventional AC-DC convener acting as a diode rectifier, such as higher energy efficiency and greater reliability resulting from the lower temperature of electronic switches.

Underwater flexible mechanoreceptors constructed by anti-swelling self-healable hydrogel

Wet-resistant flexible electronics have acquired increasing attention on applications in wet environments,such as sweaty skin, rainy weather, biological fluids, and underwater. However, it remains challenging to achieve nonswelling and underwater self-healing hydrogel sensors for the mechanical perception in aqueous solutions. Herein, a selfhealing and non-swellable hydrogel is successfully fabricated,which presents an automatically healing behavior in various aquatic environments, including deionized water, seawater,sweat, alkali and acidic aqueous solutions. Moreover, the hydrogel demonstrates high stretchability and stable electromechanical sensing properties in water. Furthermore, an electronic skin is designed with the features of fast responsiveness, reliability, and high sensitivity for detecting breathing, speaking, coughing, and diverse body movements. The self-healing hydrogel sensors enable a brilliant mechanical sensibility for detecting a series of dynamic stimuli in air and underwater, even after the healing of fracture interface in water. The underwater self-healing and anti-swelling hydrogel would provide enticing potential on various stable electronic devices for aquatic environments, such as implantable electrodes, triboelectric nanogenerators, and underwater soft robotics.

Recent advances in ionic liquid-based electrochemical biosensors

Ionic liquids （ILs） have been generally described as molten salts which are composed of asymmetric cations and anions. They exist in liquid state below 100 ℃. Both ILs and their composite materials have been widely used in various fields. Attributed to the outstanding properties including the thermal and chemical stabilities, the negligible volatility, the high ionic conductivity, the wide electrochemical window, and the easy design in the construction, ILs have been applied in electrochemical applications including the electrocatalysis, the electrosynthesis, the electrodeposition, the electrochamical devices and sensors. In addition to the application in electrochemical sensors, ILs have also been used in biosensors because of their biocompatibiciy. Here, we review the recent devel- opments for the applicaitons of ILs in electrochemical sensors and biosensors, including the corresponding properties of ILs suitable for electrochemical sensors. Electrochemical biosensors constructed by numorous composites are the emphasis in the review.

Nanowire-based transparent conductors for flexible electronics and optoelectronics

As the necessary components for various modern electronic and optoelectronic devices, novel transparent electrodes(TEs) with the low cost, abundance features, and comparable performance of indium tin oxide(ITO) are inquired materials. Metal nanowires(NWs) with the excellent photoelectric properties as next-generation TE candidates have widely applications in smart optoelectronic devices such as electronic skins, wearable electronics, robotic skins, flexible and stretchable displays. This review describes the synthetic strategies for the preparation of metal NWs, the assemble process for metal NW films,and the practical aspects of metal NW films with the desired properties in various low-cost, flexible,and solution-based photoelectric devices.

Low-power high-mobility organic single-crystal field-effect transistor

Evolving flexible electronics requires the development of high-mobility and low-power organic field-effect transistors(OFETs)that are crucial for emerging displays,sensors,and label technologies.Among diverse materials,polymer gate dielectrics and two-dimensional(2D)organic crystals have intrinsic flexibility and natural compatibility with each other for OFETs with high performance;however,their combination lacks non-impurity and non-damage construction strategies.In this study,we developed a desirable OFET system using damage-free transfer of 2D organic single crystal,dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene on a unique polymer dielectric layer,poly(amic acid)(PAA).Benefiting from the unique PAA surface nanostructure and the long-range ordered characteristics of the 2D organic single crystal,the resulting OFETs show remarkable performance with high mobility and low operating voltage of 18.7 cm^(2) V^(−1) s^(−1) and−3 V,respectively.The result indicates that combining polymer gate dielectric with 2D organic single crystal using a high-quality method can produce flexible electronic devices with high performance.

Novel ionic liquid based electrolyte for double layer capacitors with enhanced high potential stability

Developing electrolyte with high electrochemical stability is the most effective way to improve the energy density of double layer capacitors(DLCs), and ionic liquid is a promising choice. Herein, a novel ionic liquid based high potential electrolyte with a stabilizer, succinonitrile, was proposed to improve the high potential stability of the DLC. The electrolyte with 7.5 wt% succinonitrile added has a high ionic conductivity of 41.1 m S cm^(-1) under ambient temperature, and the DLC adopting this electrolyte could be charged to 3.0 V with stable cycle ability even under a discharge current density of 6 A g^(-1). Moreover, the energy density could be increased by 23.4% when the DLC was charged to 3.0 V compared to that charged to 2.7 V.

What are the practical limits for the specific surface area and capacitance of bulk sp^2 carbon materials?

The possible practical limits for the specific surface area and capacitance performance of bulk sp^2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the limit for the specific surface area to be 3500–3700 m^2 g^(-1), and based on this, the corresponding best capacitance was predicted for various electrolyte systems. A model using an effective ionic diameter for the electrolyte ions was proposed and used to calculate the theoretical capacitance. A linear dependence of experimental capacitance versus effective specific surface area of various sp^2 carbon materials was obtained for all studied ionic liquid, organic and aqueous electrolyte systems. Furthermore, excellent agreement between the theoretical and experimental capacitance was observed for all the tested sp^2 carbon materials in these electrolyte systems, indicating that this model can be applied widely in the evaluation of various carbon materials for supercapacitors.