Workingprinciple
Theavalanchephotodiodeisap-njunctionphotodetectiondiode,whichusestheavalanchemultiplicationeffectofcarrierstoamplifythephotoelectricsignaltoimprovethedetectionsensitivity.ItsbasicstructureoftenadoptstheReaddiodestructurewhichispronetoavalanchemultiplicationeffect(ieN+PIP+typestructure,P+sidereceiveslight),andalargereversebiasisappliedduringoperationtomakeitreachtheavalanchemultiplicationstate;itslightabsorptionThezoneisbasicallythesameasthemultiplicationzone(thePzoneandtheIzonewithhighelectricfield).
ThePNjunctionisappliedwithasuitablehighreversebiasvoltage,sothatthephotogeneratedcarriersinthedepletionlayerareacceleratedbyastrongelectricfieldtoobtainhighenoughkineticenergy,andtheycollidewiththelatticetoionizeandgeneratenewelectrons.Holepairs,thesecarrierscontinuetocausenewimpactionization,resultingincarrieravalanchemultiplicationandcurrentgain.Inthe0.6-0.9μmband,siliconAPDhasclosetoidealperformance.InGaAs(IndiumGalliumArsenide)/InP(IndiumPhosphorus)APDisanidealphotodetectorforlong-wavelength(1.3μn,1.55μm)opticalfibercommunication.ThelightabsorptionlayerusesInGaAsmaterial,whichhasahighabsorptioncoefficientforlightof1.3μmand1.55μn.InordertoavoidthetunnelbreakdownoftheInGaAshomojunctionbeforetheavalanchebreakdown,theavalanchezoneandtheabsorptionzoneareseparated,thatis,thePNjunctionismadeIntheInPwindowlayer.SincetheholeionizationcoefficientintheInPmaterialisgreaterthantheelectronionizationcoefficient,n-typeInPisselectedfortheavalanchezone.Thereisalargevalencebandbarrierattheheterogeneousinterfacebetweenn-InPandn-InGaAs,whichiseasytocausethecollapseofphoto-generatedholes,whichissandwichedbetweenEntertheInGaAsP(IndiumGalliumArsenidePhosphorus)transitionzonewithagradualbandgaptoformaSAGM(absorption,gradingandmultiplicationrespectively)structure.
InAPDmanufacturing,itisnecessarytoaddaprotectiveringonthesurfaceofthedevicetoimprovethereversewithstandvoltageperformance;thesemiconductormaterialispreferablySi(widelyusedtodetectlightbelow0.9um),butinthedetectionForlong-wavelengthlightabove1um,GeandInGaAsarecommonlyused(largernoiseanddarkcurrent).ThedisadvantageofthistypeofAPDisthatthereisaprocessoftunnelingcurrentmultiplication,whichwillproducelargershotnoise(reducingthep-zonedopingcanreducethetunnelingcurrent,buttheavalanchevoltagewillincrease).Animprovedstructureistheso-calledSAM-APD:themultiplicationzoneusesamaterialwithawiderbandgap(sothatitdoesnotabsorblight),andthelightabsorptionzoneusesamaterialwithanarrowbandgap;here,becauseoftheuseofheterojunction,youcanReducethedopingconcentrationofthemultiplicationregionwithoutaffectingthelightabsorptionregion,sothatthetunnelcurrentcanbereduced(ifitisamutationheterojunction,becauseoftheexistenceofΔEv,thephoto-generatedholeswillbeaccumulatedandaffectthedevice'sperformance.Responsespeed,atthistime,agradualchangelayercanbeinsertedinthemiddleofthemutationheterojunctiontoreducetheinfluenceofΔEv).
Pääominaisuudet
Pääominaisuudet①VyöryvyörykerroinM (kutsutaan myös kertojaksi), äkillisiä muutoksia varten
Kaava,Vistherversebiasvoltage jaVBonbulkavalanche-breakdownjännite;liittyy materiaaliin,
laitteen rakenne ja tapahtuman aallonpituus jne. Se on vakio, ja sen arvo on1～3.②Kaistanleveyden vahvistustuote, kun vahvistus on suuri ja taajuuskorkea,
M(ω)·ω
whereωistheangularfrequency;NisConstant,whichchangesslowlywiththeratiooftheionizationcoefficient;Wisthethicknessofthedepletionzone;Vsisthesaturationvelocity;αnandαparetheionizationcoefficientsofelectronsandholes,respectively,andthegainbandwidthproductisaconstant.Togetahighproduct,youshouldchoosealargeVs,asmallW,andasmallαn/αp(thatis,thedifferenceintheionizationcoefficientsofelectronsandholesshouldbelarge,andcarrierswithhigherionizationcoefficientsshouldbeinjectedintotheavalanchezone).③ExcessivenoisefactorF.Intheprocessofmultiplication,thenoisecurrentincreasesfasterthanthesignalcurrent.UseFtodenotethenoiseadditionF≈Mxcausedbytheavalancheprocess.Wherexistheexcessnoiseindex.ItisnecessarytoselecttheappropriatevalueofMtoobtainthebestsignal-to-noiseratioandmakethesystemreachthehighestsensitivity.④Temperaturecharacteristics,thecarrierionizationcoefficientdecreaseswiththeincreaseoftemperature,whichleadstothedecreaseofthemultiplicationfactorandtheincreaseofthebreakdownvoltage.ThetemperaturecoefficientofbreakdownvoltageisusedtodescribethetemperaturecharacteristicsofAPD.
β=
Kaavassa VB ja VB0 ovat läpilyöntijännite, kun lämpötila onTandT0.
Whenusing,thetemperatureoftheworkingpointshouldbecontrolled,andauniformP-Njunctionshouldbemadetopreventthelocaljunctionsurfacefrombeingbrokendown.
Materiaali
Teoriassa mitä tahansa puolijohdemateriaalia voidaan käyttää monistusvyöhykkeellä:
Siliconmaterialissuitableforthedetectionofvisiblelightandnear-infraredlight,andhasrelativelyhighLowmultipliernoise(excessnoise).
Germanium(Ge)-materiaali havaitsee infrapunavalon, jonka aallonpituus ei ylitä 1,7 μm, mutta moninkertaistusmelu on suhteellisen suuri.
InGaAsmaterialscandetectinfraredrayswithwavelengthsexceeding1.6μm,andthemultiplicationnoiseislowerthanthatofgermaniummaterials.Itisgenerallyusedasthemultiplicationregionofheterostructurediodes.Thismaterialissuitableforhigh-speedopticalfibercommunication,andthespeedofcommercialproductshasreached10Gbit/sorhigher.
Galliumnitridediodescanbeusedforultravioletdetection.
HgCdTediodescandetectinfraredrayswithawavelengthofupto14μm,buttheyneedtobecooledtoreducedarkcurrent.Usethisdiodetoobtainverylowexcessnoise.
Basicintroductionandapplicationrangeofbasicmodels
Eachmoduleincludesaphotodetector(fastphotodiodeoravalanchephotodiode)andatransimpedanceamplifier.Amplifierandphotodetectorarecombinedinthesamepackage,sothattheenvironmentalnoiseislowerandtheparasiticcapacitanceissmaller.
C30659seriesmodulesincludeanAPDconnectedtoalownoisetransimpedanceamplifier.Thereare4typesofsiliconcrystalavalanchephotodiodesand2typesofindiumgalliumarsenideavalanchephotodiodestochoosefrom.Thestandardbandwidthof50MHzand200MHzcanbeadaptedtoawiderangeofapplications.TherearealsotwoC30659modelsofavalanchephotodiodesequippedwiththermoelectriccooling(LLAMseries)tohelpimprovenoiseorkeeptheavalanchephotodiodesworkingataconstanttemperatureunderanyambienttemperature.
C30659modelcanchooseacustomizedbandwidthorcustomizedproductssuitableforspecialenvironmentalrequirementsaccordingtospecialapplicationneeds.Thereisalsoa14-pindualin-lineplug-inwithapigtailpackage,whichcanachievealmost100%couplingefficiency.
C30950EHisalow-costproductthatcanreplaceC30659.Theamplifierisusedtooffsettheinputcapacitanceofthevoltagegainamplifier.C30919EandC30950EHusethesamedesignstructure,withanadditionalhigh-voltagetemperaturecompensationcircuittomaintainthemodule'sresponsivenessconstantinawidetemperaturerange.TheothertwoHUVmodulescanbeusedforlowfrequencyandhighgainapplications,whichcoverawidespectrumfromultraviolettonearinfrared.
Ominaisuudet ja edut
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Yleiset mallit: C30659-900-R5BH,C30659-900-R8AH,C30659-1060-R8BH,C30659-1060-3AH
C30659-1550-R08BH,C30659-1550-R2AH,C30919E,C30950EH,LLAM-1550-R2A,LLAM-1060-R8BH
HUV-1100BGH,HUV-2000BH
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