蓝光-宽带隙激光器ppt课件

WideBandgapSemiconductor BasedLasers 王伟平2014 1 9 Part1 GaNbluelaserdiodes 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 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 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 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 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 Part2 GaN BasedVCSELandGaN ZnO BasedPolaritonLasers 2 1Introduction microcavity MC basedVCSELpolaritonlasers Withedge emittingGaN basedlasersincommercialsystems attentionisshiftingtomoredemandingandrewardingemitters High speed high resolutionlaserprintingandscanningNewtypesofcoherentopticalbutnearlythresholdlesssources Observationofspontaneousem issionbuildupinpolaritonlasingemissionisattributedtoaBose Einsteincondensateofcavitypol aritons 2 2GaN BASEDVCSEL ThebeamofaVCSELischaracterizedbyalowerdivergenceanglecomparedwiththatoftheedge emittinglasers makingthemfavoredforuseinfiber opticcommunications Gainregionisveryshortinverticalcavitydevicesascomparedtheedge emittervarieties therequiredreflectivitiesofthetopandbottomDBRsmustbewellabove90 inordertoovercomeopticallossesforlasing VCSELsemitperpendiculartotheactiveregionsurface allowingtheirfabricationinadensetwo dimensionalarray 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 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 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 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 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 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 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 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 Bose Einsteincondensation 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 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 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 2 3 2ZnO BasedMicrocavities 2 BottomDBR a30 pairAlN Al0 23Ga0 77NCavity bulkZnOTopDBR 9 pairSiO2 HfO2 Thestrongexciton photoncouplingatRThasbeenobservedfromtheZnO basedhybridmicrocavitystructure LargevacuumRabisplittingvalue about58meV 3 CONCLUSION Introducewidebandgapsemiconductorlaser includingapplications especiallyinOpticalStorage difficultiesandbreakthroughs growthtechniquesandcavitystructures Reviewedtherecentprogressinwide bandgapsemiconductor basedsurface emittinglaserstructuressuchasGaN basedVCSELsandGaN ZnO basedpolaritonlasers 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 thresholdlasingo