A 3.3 kV 4H-SiC split gate MOSFET with a central implant region for superior trade-off between static and switching performance

A split gate MOSFET(SG-MOSFET)is widely known for reducing the reverse transfer capacitance(C_(RSS)).In a 3.3 kV class,the SG-MOSFET does not provide reliable operation due to the high gate oxide electric field.In addition to the poor static performance,the SG-MOSFET has issues such as the punch through and drain-induced barrier lowering(DIBL)caused by the high gate oxide electric field.As such,a 3.3 kV 4 H-SiC split gate MOSFET with a grounded central implant region(SG-CIMOSFET)is proposed to resolve these issues and for achieving a superior trade-off between the static and switching performance.The SG-CIMOSFET has a significantly low on-resistance(R_(ON))and maximum gate oxide field(E_(OX))due to the central implant region.A grounded central implant region significantly reduces the C_(RSS)and gate drain charge(Q_(GD))by partially screening the gate-to-drain capacitive coupling.Compared to a planar MOSFET,the SG MOSFET,central implant MOSFET(CIMOSFET),the SGCIMOSFET improve the R_(ON)×Q_(GD)by 83.7%,72.4%and 44.5%,respectively.The results show that the device features not only the smallest switching energy loss but also the fastest switching time.

Methane dehydroaromatization with periodic CH_4-H_2 switch:A promising process for aromatics and hydrogen

Long-term stability test of Mo/HZSM-5-N catalysts（HZSM-5-N stands for nano-sized HZSM-5） in methane dehydroaromatization（MDA）reaction has been performed with periodic CH4-H2 switch at 1033-1073 K for more than 1000 h.During this test,methane conversion ranges from 13% to 16%,and mean yield to aromatics（i.e.benzene and naphthalene） exceeds 10%.N2-physisorption,XRD,NMR and TPO measurements were performed for the used Mo/HZSM-5 catalysts and coke deposition,and the results revealed that the periodic hydrogenation can effectively suppress coke deposition by removing the inert aromatic-type coke,thus ensuring Mo/HZSM-5 partly maintained its activity even in the presence of large amount of coke deposition.The effect of zeolite particle size on the catalytic activity was also explored,and the results showed that the nano-sized zeolite with low diffusion resistance performed better.It is recognized that the size effect was enhanced by reaction time,and it became more remarkable in a long-term MDA reaction even at a low space velocity.

A 4H-SiC trench MOSFET structure with wrap N-type pillar for low oxide field and enhanced switching performance

An optimized silicon carbide(SiC)trench metal-oxide-semiconductor field-effect transistor(MOSFET)structure with side-wall p-type pillar(p-pillar)and wrap n-type pillar(n-pillar)in the n-drain was investigated by utilizing Silvaco TCAD simulations.The optimized structure mainly includes a p+buried region,a light n-type current spreading layer(CSL),a p-type pillar region,and a wrapping n-type pillar region at the right and bottom of the p-pillar.The improved structure is named as SNPPT-MOS.The side-wall p-pillar region could better relieve the high electric field around the p+shielding region and the gate oxide in the off-state mode.The wrapping n-pillar region and CSL can also effectively reduce the specific on-resistance(Ron,sp).As a result,the SNPPT-MOS structure exhibits that the figure of merit(Fo M)related to the breakdown voltage(V_(BR))and Ron,sp(V_(BR)^2R_(on,sp))of the SNPPT-MOS is improved by 44.5%,in comparison to that of the conventional trench gate SJ MOSFET(full-SJ-MOS).In addition,the SNPPT-MOS structure achieves a much fasterwitching speed than the full-SJ-MOS,and the result indicates an appreciable reduction in the switching energy loss.

Hydrothermal Preparation and White-Light-Controlled Resistive Switching Behavior of BaWO_4 Nanospheres

In this work, BaWO4 nanospheres were successfully prepared by hydrothermal process. The bipolar resistive switching behavior of Ag/BaWO4/FTO device is observed. Moreover, this resistive switching behavior can be modulated by white light. The device can maintain superior stability in the dark and under white-light illumination. This study is useful for developing the light-controlled nonvolatile memory devices.

Effects of Electrode on Resistance Switching Properties of ZnMn_2O_4 Films Deposited by Magnetron Sputtering

ZnMn_2O_4 films for resistance random access memory（RRAM） were fabricated with different device structures by magnetron sputtering. The effects of electrode on I-V characteristics, resistance switching behavior, endurance and retention characteristics of ZnMn_2O_4 films were investigated. The ZnMn_2O_4 films, using p-Si and Pt as bottom electrode, exhibit bipolar resistive switching（BRS） behavior dominated by the space-charge-limited conduction（SCLC） mechanism in the high resistance state（HRS） and the filament conduction mechanism in the low resistance state（LRS）, but the ZnMn_2O_4 films using n-Si as bottom electrodes exhibit both bipolar and unipolar resistive switching behaviors controlled by the Poole-Frenkel（P-F） conduction mechanism in both HRS and LRS. Ag/ZnMn_2O_4/p-Si device possesses the best endurance and retention characteristics, in which the number of stable repetition switching cycle is over 1000 and the retention time is longer than 106 seconds. However, the highest RHRS/R_（LRS） ratio of 104 and the lowest V_（ON） and V_（OFF） of 3.0 V have been observed in Ag/ZnMn_2O_4/Pt device. Though the Ag/ZnMn_2O_4/n-Si device also possesses the highest RHRS/R_（LRS） ratio of 104, but the highest values of V_（ON）,V_（OFF）, RHRS and R_（LRS）, as well as the poor endurance and retention characteristics.

Resistive Switching Behavior of Ag/Mg0.2Zn0.8O/ZnMn2O4/p^+-Si Heterostructure Devices for Nonvolatile Memory Applications

The Ag/Mg0.2Zn0.8O/ZnMn2O4/p^＋-Si heterostructure devices were fabricated by sol-gel spin coating technique and the resistive switching behavior,conduction mechanism,endurance characteristic,and retention properties were investigated.A distinct bipolar resistive switching behavior of the devices was observed at room temperature.The resistance ratio R_（HRS）/RLRS of high resistance state and low resistance state is as large as four orders of magnitude with a readout voltage of 2.0 V.The dominant conduction mechanism of the device is trap-controlled space charge limited current（SCLC）.The devices exhibit good durability under 1×10^3cycles and the degradation is invisible for more than 10^6 s.

Resistance Switching Properties of Ag/Zn Mn_2O_4/p-Si Fabricated by Magnetron Sputtering for Resistance Random Access Memory

A resistance random access memory（RRAM） with a structure of Ag/ZnMn2O4/p-Si was fabricated by magnetron sputtering method. Reliable and repeated switching of the resistance of ZnMn2O4 fi lms was obtained between two well-defi ned states of high and low resistance with a narrow dispersion and 3V switching voltages. Resistance ratio of the high resistance state and low resistance state was found in the range of around 10^3 orders of magnitude and up to about 10^3 test cycles. The retention time of Ag/ZnMn2O4/p-Si device is longer than 10^6 seconds and the resistance ratio between two states remains higher than 10^3 at room temperature, showing a remarkable reliability performance of the RRAM devices for nonvolatile memory application. The equivalent simulation circuits for HRS（high resistance state） and LRS（low resistance state） were also studied by impedance spectroscopy.

Fluorescent Switch Behavior of 1, 2-Bis(4-pyridyl) Ethylene Controlled by pH in Aqueous Solution

With the decrease of pH value from 8.45 to -1.0, the UV-Vis absorption and fluorescent spectra of 1,2-bis（4-pyridyl） ethylene（BPE） took on the same changing trend at four different successive pH stages： 8.45--7.20, 7.20--5.62, 5.62--2.60, and 2.60--1.0, namely, no change, decrease, increase, and decrease again. Among these, in a range of 7.20--5.62, the fluorescence wavelength blueshifted from 418 to 359 nm, but the UV-Vis absorption wavelength, in contrast, redshifted from 285 to 298 nm. The fluorescence intensity of BPE had a drop even to quench upon a decline in the pH value from 2.60 to -1.0 probably owing to its cation-re interaction to reduce the π electron cloud density of BPE. Two dissociation constants, pKa1（4.30±0.01） and PKa2（5.65±0.04）, were obtained based on fluorescence data. The changes of fluorescence spectra indicate that BPE has ＂oft-on-off＂ switch behavior. The fluorescent spectra of BPE were nearly independent on the presence of α- and β-cyclodextrins.

Coexistence of Bipolar and Unipolar Resistive Switching Behavior in Ag/ZnMn_2O_4/p^+-Si Device

ZnMn_2O_4 thin films were deposited by a sol-gel technique onto a p+-Si substrate, and a RRAM device with the Ag/ZnMn_2O_4/p^+-Si structure was fabricated. The microstructure of ZnMn_2O_4 films and the resistive switching behavior of Ag/ZnMn_2O_4/p^+-Si device were investigated. ZnMn_2O_4 thin films had a spinel structure after annealing at 650 °C for 1 h. The Ag/ZnMn_2O_4/p^+-Si device showed unipolar and/or bipolar resistive switching behavior, exhibiting different ION/IOFF ratio and switching endurance properties. In bipolar resistive switching, high-resistance-state(HRS) conduction was dominated by the space-charge-limited conduction mechanism, whereas the filament conduction mechanism dictated the low resistance state(LRS). For unipolar resistive switching, HRS and LRS were controlled by the filament conduction mechanism. For bipolar resistive switching, the conduction process can be explained by the space-charge region of the p-n junction.

Measurement Process of MOSFET Device Parameters with VEE Pro Software for DP4T RF Switch

To design a Double-Pole Four-Throw (DP4T) RF switch, measurement of device parameters is required. In this DP4T RF switch CMOS is a unit cell, so with a thin oxide layer of thickness 628 ? which is measured optically. Some of the material parameters were found by the curve drawn between Capacitance versus Voltage (C-V) and Capacitance versus Frequency (C-F) with the application of Visual Engineering Environment Programming (VEE Pro). To perform the measurement processing at a distance, from the hazardous room, we use VEE Pro software. In this research, to acquire a fine result for RF MOSFET, we vary the voltage with minor increments and perform the measurements by vary the applying voltage from +5 V to –5 V and then back to +5 V again and then save this result in a data sheet with respect to temperature, voltage and frequency using this program. We have investigated the characteristics of RF MOSFET, which will be used for the wireless telecommunication systems.

Bipolar Resistive Switching in Epitaxial Mn_3O_4 Thin Films on Nb-Doped SrTiO_3 Substrates

Spinel （O01）-orientated Mn304 thin films on Nb-doped SrTi03 （001） substrates are fabricated via the pulsed laser deposition method. X-ray diffraction and high-resolution transmission electron microscopy indicate that the as-prepared epitaxial fihn is well crystaiHzed. In the film plane the orientation relationship between the film and the substrate is [lOOjMn3 04 ｜｜[110] Nb-doped SrTiO3. After an electroforming process, the film shows bipolar nonvolatile resistance switching behavior. The positive voltage bias drives the sample into a low resistance state, while the negative voltage switches it back to a high resistance state. The switching polarity is different from the previous studies. The complex impedance measurement suggests that the resistance switching behavior is of filament type. Due to the performance reproducibility and state stability, Mn3O4 might be a promising candidate for the resistive random access memory devices.

Characterization Process of MOSFET with Virtual Instrumentation for DP4T RF Switch – A Review

With the increasing interest in radio frequency switch by using the CMOS circuit technology for the wireless communication systems is in demand. A traditional n-MOS Single-Pole Double-Throw (SPDT) switch has good performances but only for a single operating frequency. For multiple operating frequencies, to transmitting or receiving information through the multiple antennas systems, known as MIMO systems, it a new RF switch is required which should be capable of operating with multiple antennas and frequencies as well as minimizing signal distortions and power consumption. We already have proposed a Double-Pole Four-Throw (DP4T) RF switch and in this research article we are discussing a process for the characterization of the MOSFET with Virtual Instrumentation. The procedure to characterize oxide and conductor layers that are grown or deposited on semiconductors is by studying the characteristics of a MOS capacitor that is formed of the conductor (Metal)-insulator-semiconductor layers for the purpose of RF CMOS as a switch is presented. For a capacitor formed of Metal-silicon dioxide-silicon layers with a thick oxide measured opti-cally. Some of the calculated material parameters are away from the expected values. These errors might be due to several factors such as a possible offset capacitance of the probes due to improper contact with the wafer which is measured by using the LCR (Inductance-Capacitance-Resistance) meter with the help of Visual Engineering Environment Programming (VEE Pro, a Agilent product).

Feasibility Study of Decision Making for Terminal Switching Time of LEO Satellite Constellation Based on the SGP4 Model

The high speed of low earth orbit(LEO) satellites makes the terminals at each beam tend to switch rapidly and frequently.The predictable trajectories of LEO satellites allow for predictable terminal switching,therefore a simple and highly accurate orbit prediction model is required to swiftly obtain accurate switching time.This study utilizes the simplified general perturbations(Version 4)(SGP4) model to predict the LEO satellite trajectory of WT-1,an LEO satellite developed independently by the 54th Research Institute of China Electronics Technology Group Corporation(CETC).The obtained prediction results are compared with the actual telemetry data of the WT-1,which gives the accuracy of the SGP4 predicted satellite trajectory within 1 km.The terminal entry/exit beam timing is simulated by using the SGP4 model-predicted orbit and the satellite' s own telemetry data.The simulation result shows that the error between the SGP4 model-predicted terminal entry/exit beam timing and the actual timing is less than 1 s.The influence of terminal motion on prediction is discussed.The results show that the error caused by the movement of the ground terminal on the prediction is less than 0.687 s,and the SGP4 model has a definitely practical value for terminal switching determination in the LEO constellation.

Performance of Double-Pole Four-Throw Double-Gate RF CMOS Switch in 45-nm Technology

In this paper, we have investigated the design parameters of RF CMOS switch, which will be used for the wireless tele-communication systems. A double-pole four-throw double-gate radio-frequency complementary-metal-oxide-semicon- ductor (DP4T DG RF CMOS) switch for operating at the 1 GHz is implemented with 45-nm CMOS process technology. This proposed RF switch is capable to select the data streams from the two antennas for both the transmitting and receiving processes. For the development of this DP4T DG RF CMOS switch we have explored the basic concept of the proposed switch circuit elements required for the radio frequency systems such as drain current, threshold voltage, resonant frequency, return loss, transmission loss, VSWR, resistances, capacitances, and switching speed.

Diode-pumped Doubly Q-switched Nd∶YAG Laser with Acoustic-optical Modulator and Cr^(4+)∶YAG Saturable Absorber

A diode-pumped doubly Q-switched Nd∶YAG laser operating at 1064nm both with an acoustic-optical(AO)modulator and Cr4+∶YAG saturable absorber in the cavity is demonstrated.At the incident pump power of 11.8W the laser can generate stable 8ns pulse with the peak power of 23.6kW at a 10kHz repetition rate.The pulse temporal profile is more symmetric and shorter compared with that of passively Q-switched lasers with only AO-active and Cr4+∶YAG.A reasonable analysis is developed to explain the experimental results theoretically.

兼容多平台 握持手感优异 雷神G45 PRO Switch游戏手柄

除了主机用户之外,不少玩家更愿意通过使用手柄来体验游戏,为此雷神在最近几年推出了数款多模手柄,比如我们之前曾介绍过的魔蝎三模精英游戏手柄G70,其采用的模块化设计令我们印象深刻。而在最近,雷神又推出了G45 PRO Switch游戏手柄,其设计风格以复古为主,并且兼容多平台,那么它的具体表现到底如何呢?

Improvement of hepatic fibrosis after tenofovir disoproxil fumarate switching to tenofovir alafenamide for three years

BACKGROUND Both tenofovir alafenamide(TAF)and tenofovir disoproxil fumarate(TDF)are the first-line treatments for chronic hepatitis B(CHB).We have showed switching from TDF to TAF for 96 weeks resulted in further alanine aminotransferase(ALT)improvement,but data remain lacking on the long-term benefits of TDF switching to TAF on hepatic fibrosis.AIM To assess the benefits of TDF switching to TAF for 3 years on ALT,aspartate aminotransferase(AST),and hepatic fibrosis improvement in patients with CHB.METHODS A single center retrospective study on 53 patients with CHB who were initially treated with TDF,then switched to TAF to determine dynamic patterns of ALT,AST,AST to platelet ratio index(APRI),fibrosis-4(FIB-4)scores,and shear wave elastography(SWE)reading improvement at switching week 144,and the associated factors.RESULTS The mean age was 55(28-80);45.3%,males;15.1%,clinical cirrhosis;mean baseline ALT,24.8;AST,25.7 U/L;APRI,0.37;and FIB-4,1.66.After 144 weeks TDF switching to TAF,mean ALT and AST were reduced to 19.7 and 21,respectively.From baseline to switching week 144,the rates of ALT and AST<35(male)/25(female)and<30(male)/19(female)were persistently increased;hepatic fibrosis was also improved by APRI<0.5,from 79.2%to 96.2%;FIB-4<1.45,from 52.8%to 58.5%,respectively;mean APRI was reduced to 0.27;FIB-4,to 1.38;and mean SWE reading,from 7.05 to 6.30 kPa after a mean of 109 weeks switching.The renal function was stable and the frequency of patients with glomerular filtration rate>60 mL/min was increased from 86.5%at baseline to 88.2%at switching week 144.CONCLUSION Our data confirmed that switching from TDF to TAF for 3 years results in not only persistent ALT/AST improvement,but also hepatic fibrosis improvement by APRI,FIB-4 scores,as well as SWE reading,the important clinical benefits of long-term hepatitis B virus antiviral treatment with TAF.

LD抽运Nd:YVO_4、Nd:GdVO_4和Nd:YAG激光特性比较

报道了在相同实验条件下 ,分别用Nd :YVO4 、Nd :GdVO4 和Nd :YAG三种晶体作激光介质 ,实现了连续波和Cr4 +:YAG被动调Q 1.0 6μm激光输出 ,分析对比了三种增益介质的泵浦阈值、转换效率及脉冲宽度、重复频率和峰值功率等一系列激光特性 ,为在不同运转方式下选取合适的增益介质 。

Cr^(4+)∶YAG被动调Q激光器进展

文中简要介绍了Cr4 +∶YAG晶体的可饱和吸收特性 ,重点介绍了Cr4 +∶YAG被动调Q激光器的最新进展 ,并展望了Cr4 +∶YAG被动调Q激光器的发展趋势。

杯[4]芳烃对单糖及嘧啶衍生物的分子识别和分子开关

用 AM1和 INDO/ SCI方法对八羟基杯 [4 ]芳烃与单糖及嘧啶衍生物形成的超分子体系进行理论研究 ,结果表明 ,主体通过 CH-π相互作用对单糖类进行分子识别 ,尤其对赤藓糖识别效果更好 ;主体与嘧啶没有明显的 π-π堆砌作用 ,但能识别含吸电子基团的嘧啶衍生物 ,据此可设计酸碱调控的分子开关 .讨论了配合物的 UV谱带与主体相比发生红移的原因 .