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Voltage-tunabletwo-colourquantumwellinfrareddetectorwithAl-gradedtriangularconfinementbarriersThisarticlehasbeendownloadedfromIOPscience.Pleasescrolldowntoseethefulltextarticle.2001Semicond.Sci.Technol.16285(http://iopscience.iop.org/0268-1242/16/5/301)Downloaddetails:IPAddress:222.31.38.59Thearticlewasdownloadedon15/07/2011at02:59Pleasenotethattermsandconditionsapply.Viewthetableofcontentsforthisissue,orgotothejournalhomepageformoreHomeSearchCollectionsJournalsAboutContactusMyIOPscienceINSTITUTEOFPHYSICSPUBLISHINGSEMICONDUCTORSCIENCEANDTECHNOLOGYSemicond.Sci.Technol.16(2001)285–288www.iop.org/Journals/ssPII:S0268-1242(01)15750-0Voltage-tunabletwo-colourquantumwellinfrareddetectorwithAl-gradedtriangularconfinementbarriersAGuzm´an1,JLS´anchez-Rojas1,JMGTijero1,2,JHernando1,ECalleja1,EMu˜noz1,GVergara3,RAlmaz´an3,FJS´anchez3,MVerd´u3andMTMontojo31DepartamentodeIngenier´ıaElectr´onica,ETSITelecomunicaci´on,UniversidadPolit´ecnicadeMadrid,CiudadUniversitarias/n,28040Madrid,Spain2DepartamentodeF´ısicaAplicada,EscuelaT´ecnicaSuperiordeArquitectura,UniversidadPolit´ecnicadeMadrid,Avda.JuandeHerreras/n,28040Madrid,Spain3CentrodeInvestigaci´onyDesarrollodelaArmada,ArturoSoria289,28033Madrid,SpainE-mail:guzman@die.upm.esReceived24July2000,acceptedforpublication7February2001AbstractWereportonanovelvoltage-tunablestackedboundtoquasi-continuumquantumwellinfrareddetectordesignedtoworkintwooftheatmosphericwindows(3–5and8–12µm).Inordertoimprovethegrowthprocessbymolecularbeamepitaxy,theabruptinterfacesbetweendifferentAl-contentlayerswereeliminated.AdifferentchoicebasedonAl-gradedtriangularconfinementbarrierswasusedinstead.Thisdevicecanbevoltagecontrolledduetotheformationoffielddomainsinthestackedstructurewhenanexternalbiasisapplied.Thisresultsinavoltagedropacrossthedetectorsproportionaltotheirseriesresistance.Besides,asignificantphotovoltaicresponsewasachievedinthe3–5µmregionandattributedtoanunintentionalasymmetryinthepotentialprofileforthedetectoroperatinginthisrange.1.IntroductionRecently,devicesbasedonquantumwellintersubbandtransitionshaveattractedmuchattentionbecauseoftheirusefulapplications.Inthisregard,someadvantagesthattheGaAstechnologyprovidescomparedtothestateoftheartCdHgTedetectorsarethewellknownmaturity,thelowcostandthushighyield,andtheflexibilityinbandtailoringtooperateindifferentatmosphericwindows.Onemajorfeatureofthequantumwellinfraredphotodetectors(QWIPs)isthepossibilitytoworkintwoormorespectralwindowsbyproperdesignoftheenergybands.SubstantialresearchefforthasbeendevotedtotheoptimizationofthesedevicesduetothegrowingdemandformulticolourIRdetectorsforremotetemperaturesensingandimagingsystems.Theyarealsohighlydesirablefortemperatureregistration,chemicalanalysisandtargetdiscriminationandidentification.Inaddition,rapidprogressinthistechnologyhasmadeitpossibletofabricatehigh-performancetwo-colourfocalplanearrays,whichhaveverypracticaluseinmulticolourIRcameras[1].Inapreviouswork,aboundtoquasi-continuumdevicedesignedtooperateinthe8–12µmatmosphericwindowwasdescribedandcharacterized[2].ThemajoradvantageofthisdevicewasthereplacementoftherectangularconfinementbarrierswithAl-gradedtriangularones,thuseliminatingtheabruptinterfacesbetweentwodifferent-Al-contentAlGaAslayers.Thisleadstoamoreuniformgrowth,avoidingtheuseoftwoAlcellsorgrowthinterruption.Inthispaper,th...