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ID:55834587
大小:4.80 MB
页数:63页
时间:2020-06-09
《《半导体器件物理》.ppt》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
1、MOSFETANDRELATEDDEVICEOUTLINEThePowerMOSFETTheMOSDiodeMOSFETFundamentalsMOSFETScalingCOMSandBiCOMSMOSFETonInsulatorMOSMemoryStructureSiO2metalsemiconductorSiO2semiconductordOhmiccontactTheMOSDiodeisofparamountimportantinsemiconductordevicephysicsbecausethedeviceextremelyus
2、efulinthestudyofsemiconductorsurfaces.TheIdealMOSDiodeAnidealMOSdiodeisdefinedasfollows:Atzeroappliedbias,Theonlychargesthatexistinthediodeunderanybiasingconditionsarethoseinthesemiconductorandthosewithequalbutoppositesignonthemetalsurfaceadjacenttotheoxide.Thereisnocarrie
3、rtransportthroughtheoxideunderthedirectcurrentdc)-biasingconditions,ortheresistivityoftheoxideisinfinite.OperationModesEnergyBandDiagramsAndChargeDistributionAccumulation:Accumulation:QmQS-dxChargeDistributionxE(X)ElectricFieldAnaccumulationofholesneartheoxide-semiconducto
4、rinterface.Depletion:EFVg>0EFEvEcEiChargeDistributionE(X)xElectricFieldxwQm-dStrongInversion:StrongInversion:xwmQm-dQnQscChargeDistributionElectricFieldxE(x)Oncestronginversionoccurs,averysmallincreaseinbandbendingcorrespondingtoaverysmallincreaseindepletion-layerwidthresu
5、ltsinalargeincreaseintheQnintheinversionlayer,sothesurfacedepletion-layerwithreachesamaximum,Wm.TheSurfaceDepletionRegionisthebandbendingwithboundaryconditionsinthebulkandEFEiSemiconductorsurfaceECEvEgOxidexP-typesiliconAtthesurfacethedensitiesare:IntheMOSdiode,thefollowin
6、gregionsofsurfacepotentialcanbedistinguished:Accumulationofholes(bandsbendupward)FlatbandconditionDepletionofhole(bandsbenddownward)Midgapwithns=np=ni(intrinsicconcentration)Inversion(bandsbenddownward)Thepotentialasafunctionofdistancecanbeobtainedbyusingtheone-dimensional
7、Poisson’sequation:Afterusingthedepletionapproximationthatweemployedinthestudyofp-njunctions.Thesurfacepotentialis:Thecriterionoftheonsetofstronginversion:Themaximumwidthofthesurfacedepletionregion:andSurfaceChargevs.SurfacePotentialTherelationshipbetweenWmandtheimpuritycon
8、centrationforsiliconandgalliumarsenide,whereNBisequaltoNAforP-typeandNDforn-typesemicondu
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