蓝光-宽带隙激光器ppt课件

WideBandgapSemiconductor-BasedLasers,王伟平2014-1-9,0,Part1：GaNbluelaserdiodes,1,彩色激光显示打印和扫描：快速、高分辨率存储：CD(780nm)AlGaAs基激光器VCD(635nm或650nm)AlGaInP激光器DVD(410nm)InGaN激光器,1-1Application,2,提高物镜的数值孔径NA值容量与光源波长的2次方成反比光学元部件及光盘片材料的光学透过率等限制,1-2OpticalStorage,400-430nm,1982年AlGaAs/GaAs(780nm)异质结激光器作为光源的CD播放机,1985年，KabayashiInGaAlP(670nm)红光激光器的室温连续激射,1992年，HiroyamaInGaAlP(630nm)红光半导体激光器,1996年，日亚和中村GaN(400nm)蓝紫光半导体激光器,1999年，日亚实现商品化GaN(400nm)蓝光半导体激光器寿命10000h,3,1-3DifficultiesandBreakthroughs,难点缺乏晶格常数匹配、热胀系数接近的热稳定的衬底材料p型GaN外延层难以获得突破高质量GaN外延层的生长1986年Amano利用低温生长的AlN或GaN过渡层或成核层,得到表面平坦如镜低剩余载流子浓度、高电子迁移率和高荧光效率的高质量GaN外延层,1991年首次获得GaN外延层室温光泵浦下的受激发射。低阻p-GaN的获得1989年Amano等人利用低能电子辐照实现了Mg掺杂低阻p型GaN。1991年Nakamura等人在700以上无氢的氮气氛中退火,也获得了低阻p-GaN。高质量InGaN外延层的生长有源层内由In组分涨落引起的深局域化能态是发光二极管高效发光的关键,只有掺有In的GaN有源层才可能得到室温带间跃迁。,4,1-4Growth,衬底的选择,生长技术双流生长技术外延侧向过生长悬挂式外延,5,F-P腔结构InGaN基激光器电注入的三级Bragg光栅紫光DFB激光器,1-5Cavitystructure,垂直腔面发射激光器极化声子激光器,6,Part2：GaN-BasedVCSELandGaN-/ZnO-BasedPolaritonLasers,7,2-1Introduction,microcavity(MC)-basedVCSELpolaritonlasers,Withedge-emittingGaN-basedlasersincommercialsystems,attentionisshiftingtomoredemandingandrewardingemitters.,High-speed,high-resolutionlaserprintingandscanningNewtypesofcoherentopticalbutnearlythresholdlesssources,Observationofspontaneousem-issionbuildupinpolaritonlasingemissionisattributedtoaBoseEinsteincondensateofcavitypol-aritons.,8,2-2GaN-BASEDVCSEL,ThebeamofaVCSELischaracterizedbyalowerdivergenceanglecomparedwiththatoftheedge-emittinglasers,makingthemfavoredforuseinfiber-opticcommunications.Gainregionisveryshortinverticalcavitydevicesascomparedtheedge-emittervarieties,therequiredreflectivitiesofthetopandbottomDBRsmustbewellabove90%inordertoovercomeopticallossesforlasing.,VCSELsemitperpendiculartotheactiveregionsurface,allowingtheirfabricationinadensetwo-dimensionalarray.,9,2-2-1OpticallyPumpedGaN-BasedVCSEL(1),Asignificantnarrowingoftheemissionspectrafrom2.5nmto0.1nmabovethethresholdwasobserved,whichisdirectevidenceoflasingos-illationintheIn0.1Ga0.9NVCSEL.,Science17September1999:Vol.285no.5435pp.1905-1906,Lasingactionwasobservedatawavelengthof399nmunderopticalexcitationandconfirmedbyanarrowingofthelinewidthintheemissionspectrafrom0.8nmbelowthresholdtolessthan0.1nmabovethreshold.,BottomDBR:43-pairGaN/Al0.34Ga0.66NCavity:26setsofIn0.01Ga0.99N/In0.1Ga0.9NMQWsTopDBR:15-pairZrO2/SiO2,10,2-2-1OpticallyPumpedGaN-BasedVCSEL(2),Top/BottomDBR:SiO2/HfO2Cavity:InGaN/GaN/AlGaNQWheterostructure,DemonstratedacavityQfactorexceeding600ininitialexperiments,suggestingthattheapproachcanbeusefulforblueandnearultravioletRCLEDandVCSEL.,BottomDBR:60-pairGaN/Al0.25Ga0.75NCavity:20setsofIn0.03Ga0.97N/InGaNMQWsTopDBR:15-pairSiO2/HfO2,Demonstratedquasi-continuous-wave(CW)lasingoperationatroomtemperatureusingahybridcavitystructure,11,2-2-1OpticallyPumpedGaN-BasedVCSEL(3),ExhibitedahighQfactorof460,aspontaneousemissionfactorofabout10-2,andlowthresholdof5.1mJ/cm-2.,Demonstratedthegreatpotentialofferedbythelattice-matchedAlInN/GaNmaterialsystemtorealisehighqualityMOVPE-grownadvancedoptoelectronicdevicessuchasVCSELsonGaNquasi-substrates.,Top/BottomDBR:SiO2/ZrO2Cavity:threeperiodsofIn0.02Ga0.98N(5nm)/In0.15Ga0.85N(2.5nm)QWssandwichedbetweenAl0.07Ga0.93Nlayers,BottomDBR:28-pairAlInN/GaNCavity:2setsofIn0.15Ga0.85N/GaNMQWTopDBR:23-pairAlInN/GaNDBR,Crack-freehighreflectivityDBRs,12,2-2-1OpticallyPumpedGaN-BasedVCSEL(4),Alowaveragethresholdpumpenergydensityof200J/cm2wasachievedinacrack-freeplanarhybrid.Thisisalsoconduciveforelectricalinjection.,Demonstratedanefficientcurrentinjectionschemeinmicron-scaledareasforhighcurrentdensityoperationinverticallightemittingdevicesbyusingaLMAlInNoxidizedlayer.Acurrentdensityoftheorderof20kA/cm2hasbeenachieved,avaluewhichshouldfulfilltheinjectionrequirementsfornitride-basedVCSELs.,BottomDBR:39.5-pairAl0.82In0.18N/GaNCavity:3setsofIn0.14Ga0.86N/GaNQWsTopDBR:13-pairSiO2/Si3N4,13,2-2-2ElectricallyPumpedGaN-BasedVCSEL(1),电泵浦的GaN基VCSEL难点(1)难以获得具有高质量和高反射率的DBRAlxGa1-xN和GaN之间折射率相差较大,因此二者搭配而成的DBR为GaN基VCSEL所普遍采用。但AlxGa1-xN和GaN之间晶格失配严重,它们的热膨胀系数也相差较大。(2)缺少合适的p型接触电极材料p型GaN的功函数很高,很难找到理想的低阻欧姆接触电极材料。VCSEL的电流注入既要求低接触电阻又要求出光孔径具有非常低的光学损耗,更增大了电极材料的难度。解决方案：在AlN/GaNDBR的制造过程中引入了超晶格结构,在出光孔径上以氧化铟锡(ITO)作为接触电极。,14,2-2-2ElectricallyPumpedGaN-BasedVCSEL(2),BottomDBR:29-pairAlN/GaNDBRthreesetsofa5.5-pairofAlN/GaNsuperlatticewasinsertedeveryfourpairsofAlN/GaNCavity:n-GaN(790nm)tenperiodsofIn0.2Ga0.8N(2.5nm)/GaN(7.5nm)MQWsp-GaN(120nm)TopDBR:8-pairTa2O5/SiO2DBR,15,2-2-2ElectricallyPumpedGaN-BasedVCSEL(3),BottomDBR:7-pairSiO2/Nb2O5Cavity:n-GaN(790nm)2-pairofInGaN(9nm)/GaN(13nm)MQWsp-GaN(120nm)TopDBR:11.5-pairSiO2/Nb2O5,Fabricatedavertical-current-injectionGaN-basedVCSELLasingactionatRTwasrealizedunderCWcurrentoperation.,16,2-3WideBandgapSemiconductorPolaritonDevices,在1996年Imamoglu及其合作者提出了极化声子激光器的概念,他们是基于一种叫激子极化声子的准粒子提出此概念，这种准粒子由光和物质组成，产生于适当设计的半导体晶体结构中。,Polariton,BoseEinsteincondensation,LasingCondition,PolaritonLasers,Extremelylowthresholdlasers,1998年，LeSiDang与其合作者在液氦温度下观察到极化激光。2007年，Southampton和Lausanne团队实现了具有光泵的第一个室温极化声子激光器。2012年，Iorsh基于氮化镓（GaN）微腔的电泵浦极化声子激光器优化方案。,17,2-3-1GaN-BasedMicrocavities-PolaritonLasers,ArealisticmodelforaroomtemperaturepolaritonlaserhasbeenproposedforaGaNMC.Itshowsanextremelylowthresholdpoweratroomtemperatureandahighquantumefficiency.,BottomDBR:11-pairAl0.2Ga0.8N/Al0.9Ga0.1NCavity:9GaNQWsfourmonolayersTopDBR:14-pairAl0.2Ga0.8N/Al0.9Ga0.1N,BottomDBR:34-pairAl0.85In0.15N/Al0.2Ga0:8NCavity:bulkGaNTopDBR:10-pairSiO2/Si3N4,Observearoom-temperaturelow-thresholdtransitiontoacoherentpolaritonstateinbulkGaNmicrocavitiesinthestrong-couplingregime.Aclearemissionthresholdof1mW,1orderofmagnitudesmallerthanthebestopticallypumped(In,Ga)Nquantum-wellVCSELs,18,2-3-2ZnO-BasedMicrocavities(1),Anotherwide-bandgapsemiconductor,ZnO,isanattractivecandidateforUVoptoelectronicsdevices.ZnOhasanexcitonbindingenergy(60meV)thatismorethantwicethatofGaN(26meV).,BottomDBR:29-pairAl0.5Ga0.5N/GaNCavity:bulkZnOTopDBR:8-pairSiO2/Si3N4,Rabisplitting,AlargevacuumRabisplittingof50meVatRTwasobtained,whichislargerthanthatobservedinbulkGaN-basedMCs.ResultsindicatethatZnO-basedmicrocavitiescanbeusedtorealizepolaritonlasers.,19,2-3-2ZnO-BasedMicrocavities(2),BottomDBR:a30-pairAlN/Al0.23Ga0.77NCavity:bulkZnOTopDBR:9-pairSiO2/HfO2,Thestrongexciton-photoncouplingatRThasbeenobservedfromtheZnO-basedhybridmicrocavitystructure.LargevacuumRabisplittingvalue:about58meV,20,3.CONCLUSION,Introducewidebandgapsemiconductorlaser,includingapplications,especiallyinOpticalStorage,difficultiesandbreakthroughs,growthtechniquesandcavitystructures.,Reviewedtherecentprogressinwide-bandgapsemiconductor-basedsurface-emittinglaserstructuressuchasGaN-basedVCSELsandGaN-/ZnO-basedpolaritonlasers.,21,References,Thebluelaserdiode半导体蓝光激光器WideBandgapSemiconductor-BasedSurface-EmittingLasersLasingemissionfromanInGaNVCSEL宽禁带GaN基半导体激光器进展GaN基蓝光半导体激光器的发展蓝光激光器的应用与发展AverticalcavitylightemittingInGaNquantumwellheterostructureNearultravioletopticallypumpedverticalcavitylaser低维半身傩结构材料及其器件应用研究迹展为什么我们需要极化声子激光器?电注入连续波蓝光GaN基CavitypolaritonsinZnO-basedhybridmicrocavitiesRoom-TemperaturePolaritonLasinginSemiconductorMicrocavities垂直腔面发射激光器半导体泵浦全固体蓝光激光器的研究进展Low-thresholdlasin