英文翻译及文献 电子电子 功率半导体

NewGenerationofHigh–PowerSemiconductorClosingSwitchesforPulsedPowerApplicationsI.IntroductionSolidstatesemiconductorswitchesareveryinvitingtouseatpulsedpowersystemsbecausetheseswitcheshavehighreliability,longlifetime,lowcostsduringusing,andenvironmentalsafetyduetomercuryandleadareabsent.Semiconductorswitchesareabletoworkinanyposition,so,itispossibletodesignsystemsasforstationarylaboratoryusing,andformobileusing.Thereforetheseswitchesarefrequentlyregardedasreplacementofgas-dischargedevices–ignitrons,thyratrons,sparkgapsandvacuumswitchesthatgenerallyusenowinhigh-powerelectrophysicalsystemsincludingpowerlasers.Traditionalthyristors(SCR)aresemiconductorswitchesmostlyusingforpulsedevices.SCRhassmallvalueofforwardvoltagedropatswitch-onstate,ithashighoverloadcapacityforcurrent,andatlastithasrelativelylowcostvalueduetothesimplebipolartechnology.DisadvantageofSCRisobservedatswitchingofcurrentpulseswithveryhighpeakvalueandshortduration.Reasonofthisdisadvantageissufficientlyslowprocessofswitch-onstateexpansionfromtriggeringelectrodetoexternalborderofp-njunctionaftertriggeringpulseapplying.ThisSCRfeatureisdefinedSCRusingintomillisecondrangeofcurrentswitching.ImprovementofSCRpulsecharacteristicscanbereachedbyusingofthedistributedgatedesign.Thisisallowedtodecreasethetimeoftotalswitch-onandgreatlyimproveSCRswitchingcapacity.Thus,ABBcompanyisexpandedthesemiconductorswitchusinguptomicrosecondrangebydesignofspecialpulseasymmetricthyristors(ASCR).ThesedeviceshavedistributinggatestructurelikeaGTO.Thisthyristordesignandforcedtriggeringmodeareobtainedthehighswitchingcapacityofthyristor(pI=150kA,pT=50μs,di/dt=18kA/μs,singlepulse).However,inthisdesigngatestructureiscoveredlargeactiveareaofthyristor(morethan50%)thatdecreasetheefficiencyofSiusingandincreasecostofdevice.Si-thyristorsandIGBThavedemonstratedhighswitchingcharacteristicsatrepetitivemode.However,suchdevicesdonotintendforswitchingofhighpulsecurrents(tensofkiloamperesandmore)becauseofwell-knownphysicallimitsareexistedsuchaslowdopingofemitters,shortlifetimeofminoritycarriers,smallsizesofchipsetc.Ourinvestigationhaveobtainedthatswitchesbasedonreverse–switcheddinistorsaremoreperspectivesolid-stateswitchestoswitchsuperhighpowersatmicrosecondandsubmillisecondranges.Reverse–switcheddinistors(RSD)istwo-electrodeanalogueofreverseconductingthyristorwithmonolithicalintegratedfreewheelingdiodeinSi.ThisdiodeisconnectedinparallelandinthebackdirectiontothethyristorpartofRSD.TriggeringofRSDisprovidedbyshortpulseoftriggercurrentatbriefapplyingofreversalvoltagetoRSD.DesignofRSDismadethusthattriggeringcurrentpassesthroughdiodeareasofRSDquasiaxiallyanduniformlyalongtheSistructurearea.Thiscurrentproducestheoncominginjectionofchargecarriersfrombothemitterjunctionstobaseregionsandinitiatestheregenerativeprocessofswitch-onforRSDthyristorareas.SuchmethodoftriggeringforthisspecialdesignofSiplateisprovidedtotalanduniformswitchingofRSDalongallactiveareaintheveryshorttimelikeasdiodeswitch-on.ThefreewheelingdiodeintegratedintotheRSDstructurecouldbeusedasdampingdiodeatfaultmodeinthedischargecircuit.Thisfaultmodesuchasbreakdownofcablelinescanleadtooscillatingcurrentthroughswitch..IthasbeenexperimentallyobtainedinthatsemiconductorswitchesbasedonRSDcanworksuccessfullyinthepulsedpowersystemstodriveflashlampspumpinghigh-powerneodymiumlasers.ItwasshowninthatRSD-switchesbasedonRSDwaferdiameterof63mm(switchtypeKRD-25-100)andRSD-switchesbasedonRSDwaferdiameterof76mm(switchtypeKRD-25-180)canswitchthecurrentpulseswithsubmilliseconddurationandpeakvalueof120kAand180kArespectively.Threeswitches(switchtypeKRD–25-180)connectedinparallelweresuccessfullytestedunderthefollowingmode:operatingvoltageoV=25kV,operatingcurrentIp=470kA,andtransferredchargeQ=145Coulombs.During2000–2001,thecapacitorbankforneodymiumlaseroffacilityLUCHwasbuiltatRFNC-VNIIEF.Thisbankincluding18switchestypeKRD-25-100operatessuccessfullyduring5yearswithoutanyfailuresofswitches.Thisreportissubmittedresultsofdevelopmentofnewgenerationofsolidstateswitcheshavinglowlossesofpowerandhigh-currentswitchingcapacity.II.DevelopmentofRSD’snextgenerationThetechnologyoffabricationofnewRSDstructurehasbeendevelopedtoincreasetheswitchingcapacity.ThisnewstructureisSPT(SoftPunchThrough)-structure-with“soft”closingofspace-chargeregionintobuffern'-layer.Decreasingofn-basethicknessandalsoimprovingofRSDswitch-onuniformitybygoodspreadingofchargecarriersonthen'-layeratvoltageinversionareprovideddecreasingofallcomponentsoflossesenergysuchaslossesattriggering,lossesattransientprocessofswitch-on,andlossesatstate-on.OurpreliminaryestimationwasshownthatsuchstructuremustprovidetheincreasingofoperatingpeakcurrentthroughRSDapproximatelyin1.5times.InvestigationswerecarriedoutforRSDwithblockingvoltageof2.4kVandSiwaferdiametersof63,76,and100mmbyspecialteststation.ThemaingoaloftheseinvestigationsisdefinitionofmaximumpermissiblelevelofpeakcurrentpassingthroughsingleRSDwithgivenarea.CurrentpassingthroughRSDandvoltagedroponRSDstructureduringcurrentpassingaremeasuredattesting.InFig.1waveformso