A super junction SiGe low-loss fast switching power diode

This paper proposes a novel super junction （S J） SiGe switching power diode which has a columnar structure of alternating p- and n- doped pillar substituting conventional n- base region and has far thinner strained SiGe p＋ layer to overcome the drawbacks of existing Si switching power diode. The SJ SiGe diode can achieve low specific on-resistance, high breakdown voltages and fast switching speed. The results indicate that the forward voltage drop of SJ SiGe diode is much lower than that of conventional Si power diode when the operating current densities do not exceed 1000 A/cm^2, which is very good for getting lower operating loss. The forward voltage drop of the Si diode is 0.66V whereas that of the SJ SiGe diode is only 0.52V voltages are 203 V for the former and 235 V for the latter. at operating current density of 10A/cm^2. The breakdown Compared with the conventional Si power diode, the reverse recovery time of SJ SiGe diode with 20 per cent Ge content is shortened by above a half and the peak reverse current is reduced by over 15%. The SJ SiGe diode can remarkably improve the characteristics of power diode by combining the merits of both SJ structure and SiGe material.

Vacuum Switching Technology for Future of Power Systems

Even though switching in vacuum is a technology with almost 100 years of history,its recent develop-ments are still changing the future of power transmission and distribution systems.First,current switch-ing in vacuum is an eco-friendly technology compared to switching in SF 6 gas,which is the strongest greenhouse gas according to the Kyoto Protocol.Vacuum,an eco-friendly natural medium,is promising for reducing the usage of SF 6 gas in current switching in transmission voltage.Second,switching in vacuum achieves faster current interruption than existing alternating current(AC)switching technolo-gies.A vacuum circuit breaker(VCB)that uses an electromagnetic repulsion actuator is able to achieve a theoretical limit of AC interruption,which can interrupt a short-circuit current in the first half-cycle of a fault current,compared to the more common three cycles for existing current switching technologies.This can thus greatly enhance the transient stability of power networks in the presence of short-circuit faults,especially for ultra-and extra-high-voltage power transmission lines.Third,based on fast vacuum switching technology,various brilliant applications emerge,which are benefiting the power systems.They include the applications in the fields of direct current(DC)circuit breakers(CBs),fault current lim-iting,power quality improvement,generator CBs,and so forth.Fast vacuum switching technology is promising for controlled switching technology in power systems because it has low variation in terms of opening and closing times.With this controlled switching,vacuum switching technology may change the“gene”of power systems,by which power switching transients will become smoother.

Study of the Fast-Closing Switch Used for Fault Current Limiters in Power System

This paper presents a new type of fault current limiter (FCL) based on fast closing switch, which is composed of a capacitor bank and a reactor in series. The main control component is a fast closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. It can response the order within 1 ms. When fault occurs, the switch closes and the capacitors are bypassed, and the fault current is limited by the reactor. Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast closing switch, it is feasible to develop the FCL with low cost and high reliability.

Global Synchronization of Directed Networks with Fast Switching Topologies

Global synchronization of a class of directed dynamical networks with switching topologies is investigated.It is found that if there is a directed spanning tree in the fixed time-average of network topology and the time-averageis achieved sufficiently fast,then the network will reach global synchronization for sufficiently large coupling strength.

Stability and stabilisation of Markovian jump systems under fast switching: an averaging approach

ABSTRACTThis paper addresses the problems of stability and stabilisation of Markovian jump systems(MJSs) with fast switching. First, a novel model by applying an averaging approach to the fastswitching is proposed. Then, a new method for constructing an auxiliary system is given to makethe stability analysis. It is proved that the stability of the originally fast switching MJS couldbe guaranteed by an MJS with an average switching, if the fast switching achieves its averageapproximation sufficiently fast. Based on the proposed results, some extensions about generally stabilising controllers are considered, where the fault-tolerant situation is involved too.All the conditions are presented in terms of LMIs. Finally, two numerical examples are used todemonstrate the effectiveness and superiority of the method.

A snapback-free and high-speed SOI LIGBT with double trenches and embedded fully NPN structure

A novel 600 V snapback-free high-speed silicon-on-insulator lateral insulated gate bipolar transistor is proposed and investigated by simulation.The proposed device features an embedded NPN structure at the anode side,and double trenches together with an N-type carrier storage(N-CS)layer at the cathode side,named DT-NPN LIGBT.The NPN structure not only acts as an electron barrier to eliminate the snapback effect in the on-state within a smaller cell pitch but also provides an extra electron extracting path during the turn-off stage to decrease the turnoff loss(E_(off)).The double cathode trenches and N-CS layer hinder the hole from being extracted by the cathode quickly.They then enhance carrier storing effect and lead to a reduced on-state voltage drop(V_(on)).The latch-up immunity is improved by the double cathode trenches.Hence,the DT-NPN LIGBT obtains a superior tradeoff between the V_(on)and E_(off).Additionally,the DT-NPN LIGBT exhibits an improved blocking capability and weak dependence of breakdown voltage(BV)on the P+anode doping concentration because the NPN structure suppresses triggering the PNP transistor.The proposed LIGBT reduces the E_(off)by 55%at the same V_(on),and improves the BV by 7.3%compared to the conventional LIGBT.

A Quantitative LC-MS/MS Study of the Partitioning, Transport, and Fate of Pesticide Residues on Soil

Titration of pesticides onto sorption sites can determine sorption capacities on soils. Previous studies have tracked the sorption capacities and detailed kinetics of the uptake of atrazine and its decomposition byproduct hydroxyatrazine on different soils, including measurements made using LC-MS/MS. These studies have now been extended to explore sorption-desorption equilibria for a mixture of pesticides from soil using LC-MS/MS. Desorption of sorbed pesticide residues has environmental regulatory implications for pesticide levels in runoff, or for longer term sequestration, partitioning, and transport. The uptake of pesticides by the soil at equilibrium was measured for a number of different concentrations, and sorption capacities were estimated. Pesticide-soil interaction studies were conducted by exposing standard stock solutions of pesticide mixtures to a characterized Nova Scotia soil. The mixture contained atrazine and dicamba. Initial aqueous mixture concentrations ranging from 5 × 10-9 to 10-5 M or greater were exposed to 25 mg aliquots of soil and allowed to reach equilibrium. The total uptake of each pesticide was measured indirectly, by measuring the concentration remaining in solution using an IONICS 3Q 120 triple quadrupole mass spectrometer. These sorption capacities have been supplemented by studies examining equilibrium recovery rates from soil aliquots with different initial uptakes. This gives insight into the fraction of easily recoverable (reversibly sorbed) pesticides on the soil. Proper quantification of equilibrium constants and kinetic rate coefficients using high performance LC-MS/MS facilitates the construction of accurate, predictive models. Predictive kinetic models can successfully mimic the experimental results for solution concentration, labile sorption, and intra-particle diffusion, and could be used to guide regulatory practices.

Ferroelectric liquid crystals for fast switchable circular Dammann grating [Invited]

Diffractive optical elements attract a considerable amount of attention, mainly due to their potential applications in imaging coding, optical sensing, etc. Application of ferroelectric liquid crystals(FLCs) with photoalignment technology in diffractive optical elements results in a high efficiency and a fast response time. In this study we demonstrate a circular Dammann grating(CDG) with a diffraction efficiency of 84.5%. The achieved response time of 64 μs is approximately two orders of magnitude faster than the existing response time of nematic liquid crystal devices. By applying a low electric field(V = 6 V) to the FLC CDG, it is switched between the eight-order diffractive state and the transmissive diffraction-free state.

光/蒸气协同构建交联多孔聚合物复合结构基超稳定高速阻变存储器

有机阻变存储器由两个电极及夹在其间的阻变聚合物层组成,具有湿法制备和功能可调的优点.然而,该类存储器还存在结构稳定性差、开关速度慢和图案化困难等问题.在本文中,我们利用光/蒸汽协同方法制备了一种具有交联多孔复合结构的非晶态聚合物薄膜,并将其作为阻变活性材料构建了一种具有高稳定性和高读取速度特征的存储阵列.所制备的聚合物二极管表现出非易失性的FLASH存储特性,具有高开关比、长维持时间以及快速信息写入(70 ns)和擦除(845 ns)等特征.令人印象深刻的是,该存储器件能够承受紫外辐射和极端温度等恶劣环境的考验.通过将存储阵列和特定传感器集成,构建了能模拟视觉/热感知和记忆功能的人造感知记忆系统,表明该系统在仿生神经形态电子领域具有巨大的应用潜力.该工作为制备具有高稳定性和高读取速度特征的聚合物存储阵列提供了一种可靠的策略.

A high performance carrier stored trench bipolar transistor with a field-modified P-base region

A novel high performance carrier stored trench bipolar transistor （CSTBT） with a field- modified P-base region is proposed. Due to the p-pillars inserted into the drift region extending the P-base region to the bottom of the trench gate, the electric field around the trench gate is modified, preventing the CSTBT from breakdown in advance caused by a concentration of the electric field at the edge of the trench gate. The p-pillars under the p-well forming the novel P-base region also provide extra paths for hole transportation. Thus, the switching time is also reduced. Simulation results have shown that the blocking voltage （BV） of the novel CSTBT is almost 430 V higher exhibiting avalanche breakdown properties compared with the conventional CSTBT. Moreover, the turn-off time of the novel structure is 0.3μs （17%） shorter than the conventional CSTBT with the same gate length.

A Conjugated Copolymer Bearing Imidazolium-based Ionic Liquid:Electrochemical Synthesis and Electrochromic Properties

An imidazolium-based ionic liquid(IL)modified triphenylamine derivative,namely 1-(4-((4-(diphenylamino)benzoyl)oxy)butyl)-3-methyl imidazole tetrafluoroborate(TPAC_(6)IL-BF_(4)),was designed and synthesized,and further applied with 3,4-ethylene dioxythiophene(EDOT)to prepare conjugated copolymer P(EDOT:TPAC_(6)IL-BF_(4)) via electrochemical polymerization.The cyclic voltammetry curves show that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))possesses two pairs of redox peaks,which should be ascribed to the redox behaviors of EDOT and triphenylamine.The ultraviolet-visible(UV-Vis)absorption spectrum of P(EDOT:TPAC_(6)IL-BF_(4))exhibits one maximum absorption peak at 580 nm and a small shoulder characteristic peak at 385 nm under neutral state which are assigned toπ-π^(*)conjugated structure of EDOT and triphenylamine.After being applied at the positive voltage,the copolymer color changes from dark blue to light blue,which is close to the color of poly(3,4-ethylenedioxythiophene)(PEDOT).Surprisingly,the copolymer P(EDOT:TPAC_(6)IL-BF_(4))shows shorter switching time of 0.37 s,0.30 s at 580 nm and 0.38 s,0.45 s at 1100 nm compared with PEDOT.It is more intriguing that the copolymer P(EDOT:TPAC_(6)IL-BF_(4))exhibits electrochromism even in free supporting electrolyte.The results confirm that the existence of imidazolium-based ionic liquid has an improvement on the ion diffusion properties and the switching time of conjugated polymer,which may provide a potential direction for the preparation of high-performance electrochromic materials.