AlGaN基深紫外发光二极管的光电热特性研究

[33]。正向偏置下的隧穿电流IT与正向电压VIe为电子电荷；IA为前指数因子常数，可以通过实验或数值推导；Rseries为串联电阻，ET为特征隧穿能量，表示界面能量势垒的隧穿透过率根据该片参考文献，本文可以大致推测使用三明治EBLs结构，在小注入电流范围内，ET可达到121meV热阻分析由图5-10可知，芯片、AlN-DPCLF、AlMCPCB在积分曲线和微分曲线所处位置，并且粘黏剂AuSn、Cu具有极小的热阻，验证了其具有良好的导热性。图5-10275nmLED的热阻积分曲线、微分曲线θ将热阻值通过相关公式5-6，可以得出相关界面的温度，并将其绘制成热传导模型，见图5-11。在输入功率为0.76W的热阻分析中得到芯片、框架、印制电路板空气的热阻值分别为5.53、11.16、4.61、38.54℃/W。本文的AlN-DPCLF、AlMCPCB、空气的理论热阻值与相关材料的参考值对比，处于正常范围内。芯片的热阻值已经是在优良的范围内，只比PCB大1℃/W。也侧面验证了本文探讨的UV-LED缺陷密度极少。在通过计算可得知，在环境温度为25℃时，结温已经达到了70.48℃，与图5-4和5-8验证了大部分的能量转化成热能，说明热管理仍是未来需要继续攻克的问题。图5-11275nmLED的热传导模型由图5-11可以看出AlN-DPCLF的热阻值在整个热传导模型中(除空气热阻值外)是最大的，说明其热传导率相对较差。但本文探讨UVC-LED的发光波长为275nm，在200~500nm的波长范围内，Al的反射系数最高，可以减少支架吸收紫外光，使更多的深紫外光可以输出，所以选用见含Al的DPCLF，图5-12。图5-12Au、Al、Ag反射系数与波长的关系结论本文基于LP-MOCVD技术探讨UVC-LED外延层设计，从减少UV-LED有源区缺陷程度的角度来改善275nmUV-LED的光电热特性。实验结果显示UVC-LED得到一定程度的提升。主要实验结果如下：使用XRD检测①、②、③峰值，实验结果显示①、②、③衍射峰的强度高，FWHM分别为1.026、0.524、0.410Sec-1。说明其缺陷密度很小，晶体质量很好。在光电特性实验中，使用电致发光技术检测整体发光情况，实验结果显示峰值波长具有较小的FWHM，并且工作温度、电流均不会影响峰值波长的变化。并且在实验条件下暂未出现寄生波或者红移或者蓝移的现象。在光电特性实验中，LOP实验结果说明在较大工作电流下，未出现辐射复合饱和情况。但LOP的斜率拐点与EQE下降拐点均在电流40mA，呈现辐射复合饱和的趋势，侧面验证了位错和杂质含量较少；电流大于40mA后，参与非辐射复合的电子-空穴对占比逐渐增加。UV-LED的EQE实验结果中，最大值为2.37%。说明本文探讨的LED品质属于世界良好水平，并具有商业化的可能与价值。在室温25℃的热阻特性测试中，芯片结温达到70.48℃，芯片、框架、印制电路板、空气的热阻值分别为5.53、11.16、4.61、38.54℃/W。存在超过芯片承载温度使发光效率快速降低、损坏芯片的可能。ADDINNE.Bib[参考文献]SilveiraE,FreitasJA,GlembockiOJetal.ExcitonicstructureofbulkAlNfromopticalreflectivityandcathodoluminescencemeasurements[J].Phys.Rev.B,2005,71(4):41201BhuiyanAG,SugitaK,KasashimaK,etal.Single-crystallineInNfilmswithanabsorptionedgebetween0.7and2eVgrownusingdifferenttechniquesandevidenceoftheactualbandgapenergy[J].AppliedPhysicsLetters,2004,84(23):452-452.HaldarS,SenD.Onthebandgapofindiumnitride[J].physicastatussolidi(b),2003:439-447.Nakamura,Shuji.InGaN/AlGaNblue‐light‐emittingdiodes[J].JournalofVacuumScience&TechnologyAVacuumSurfaces&Films,1995,13(3):705-710.NakamuraS.InGaN-basedbluelaserdiodes[J].IEEEJournalofSelectedTopicsinQuantumElectronics,1997,3(3):712-718.JaniO,FergusonI,HonsbergC,etal.DesignandcharacterizationofGaN∕InGaNsolarcells[J].AppliedPhysicsLetters,2007,91(13):1-20.KhanMA,KuzniaJN,OlsonDT,etal.SchottkybarrierphotodetectorbasedonMg-dopedp-typeGaNfilms[J].AppliedPhysicsLetters,1993,63(18):2455-2456.谭斐,杨映霞.广西地面太阳辐射分布特征以及对人体健康的影响S14[C]//中国气象学会.中国气象学会,2011.ChatterleyC,LindenR.DemonstrationandevaluationofgermicidalUV-LEDsforpoint-of-usewaterdisinfection.[J].JournalofWaterandHealth,2010,8(3):479-486.Honigsmann,H.Historyofphototherapyindermatology[J].Photochemical&PhotobiologicalSciences,2013.FowlesM,WayneRP.OzonemonitorusinganLEDsource[J].J.phys.eInstrum,1981,14(10):1143.G.Wiegleb.EinsatzvonLED-StrahlungsquelleninAnalysengeräten.LaserundOptoelektronik3,308–3110(1985)KneisslM,YangZ,TeepeM,etal.UltravioletInAlGaNLightEmittingDiodesGrownonHydrideVaporPhaseEpitaxyAlGaN/SapphireTemplates[J].JapaneseJournalofAppliedPhysics,2006,45(5A):3905-3908.KusanoM,TohgeT,FukushimaA,etal.MetabolomicsrevealscomprehensivereprogramminginvolvingtwoindependentmetabolicresponsesofArabidopsistoUV-Blight[J].ThePlantJournal,2011,67(2):354-369.Nam,K.B,Li,etal.UniqueopticalpropertiesofAlGaNalloysandrelatedultravioletemitters.[J].AppliedPhysicsLetters,2004,84(25):5264.KolbeT,KnauerA,ChuaC,etal.Opticalpolarizationcharacteristicsofultraviolet(In)(Al)GaNmultiplequantumwelllightemittingdiodes[J].AppliedPhysicsLetters,2010,97(17):171105-171105-3.RyuHY,ChoiIG,ChoiHS,etal.InvestigationofLightExtractionEfficiencyinAlGaNDeep-UltravioletLight-EmittingDiodes[C]//Lasers&Electro-opticsPacificRim.2013.FYun,ReshchikovMA,HeL,etal.EnergybandbowingparameterinAlxGa1-xNalloys[J].JournalofAppliedPhysics,2002,92(8):4837-4839.ChichibuSF,AbareAC,MinskyMS,etal.EffectivebandgapinhomogeneityandpiezoelectricfieldinInGaN/GaNmultiquantumwellstructures[J].AppliedPhysicsLetters,1998,73(14):2006-2008.MillerD,ChemlaDS,DamenTC,etal.Band-EdgeElectroabsorptioninQuantumWellStructures:TheQuantum-ConfinedStarkEffect[J].PhysicalReviewLetters,1984,53(22):2173--2176.程文进,巩小亮,陈峰武,彭立波,魏唯.高温MOCVD外延生长AlN材料研究[J].电子工业专用设备,2017,46(04):43-49.EsakiL,TsuR.Superlatticeandnegativedifferentialconductivityinsemiconductors[J].IBMJ.Res.Dev.,1970,14(1):61~65ZhangJP,WangHM,GaevskiMEetal.Crack-freethickAlGaNgrownonsapphireusingAIN/AlGaNsuperlatticesforstrainmanagement[J].AppliedPhysicsLetters,2002,80(19):3542-3544.WangHM,ZhangJP,ChenCQ,etal.AlN/AlGaNsuperlatticesasdislocationfilterforlow-threading-dislocationthickAlGaNlayersonsapphire[J].AppliedPhysicsLetters,2002,81(4):604-606.李洋.AlGaN基深紫外LED的MOCVD外延生长[D].华中科技大学,2015.MukaiT,NakamuraS.UltravioletInGaNandGaNSingle-Quantum-Well-StructureLight-EmittingDiodesGrownonEpitaxiallyLaterallyOvergrownGaNSubstrates[J].JapaneseJournalofAppliedPhysics,1999,38(Part1,No.10):5735-5739.C.H.Wang,C.C.Ke,C.Y.Lee,S.P.Chang,W.T.Chang,J.C.Li,Z.Y.Li,H.C.Yang,H.C.Kuo,T.C.Lu,andS.C.Wang.HoleinjectionandefficiencydroopimprovementinInGaN/GaNlight-emittingdiodesbyband-engineeredelectronblockinglayer[J].AppliedPhysicsLetters,2010,97(26):183507.ZhangL,WeiXC,LiuNX,etal.Improvementofeff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