AlGaN基深紫外發(fā)光二極管的光電熱特性研究

[33]。正向偏置下的隧穿電流IT與正向電壓VIe為電子電荷；IA為前指數(shù)因子常數(shù)，可以通過(guò)實(shí)驗(yàn)或數(shù)值推導(dǎo)；Rseries為串聯(lián)電阻，ET為特征隧穿能量，表示界面能量勢(shì)壘的隧穿透過(guò)率根據(jù)該片參考文獻(xiàn)，本文可以大致推測(cè)使用三明治EBLs結(jié)構(gòu)，在小注入電流范圍內(nèi)，ET可達(dá)到121meV熱阻分析由圖5-10可知，芯片、AlN-DPCLF、AlMCPCB在積分曲線和微分曲線所處位置，并且粘黏劑AuSn、Cu具有極小的熱阻，驗(yàn)證了其具有良好的導(dǎo)熱性。圖5-10275nmLED的熱阻積分曲線、微分曲線θ將熱阻值通過(guò)相關(guān)公式5-6，可以得出相關(guān)界面的溫度，并將其繪制成熱傳導(dǎo)模型，見(jiàn)圖5-11。在輸入功率為0.76W的熱阻分析中得到芯片、框架、印制電路板空氣的熱阻值分別為5.53、11.16、4.61、38.54℃/W。本文的AlN-DPCLF、AlMCPCB、空氣的理論熱阻值與相關(guān)材料的參考值對(duì)比，處于正常范圍內(nèi)。芯片的熱阻值已經(jīng)是在優(yōu)良的范圍內(nèi)，只比PCB大1℃/W。也側(cè)面驗(yàn)證了本文探討的UV-LED缺陷密度極少。在通過(guò)計(jì)算可得知，在環(huán)境溫度為25℃時(shí)，結(jié)溫已經(jīng)達(dá)到了70.48℃，與圖5-4和5-8驗(yàn)證了大部分的能量轉(zhuǎn)化成熱能，說(shuō)明熱管理仍是未來(lái)需要繼續(xù)攻克的問(wèn)題。圖5-11275nmLED的熱傳導(dǎo)模型由圖5-11可以看出AlN-DPCLF的熱阻值在整個(gè)熱傳導(dǎo)模型中(除空氣熱阻值外)是最大的，說(shuō)明其熱傳導(dǎo)率相對(duì)較差。但本文探討UVC-LED的發(fā)光波長(zhǎng)為275nm，在200~500nm的波長(zhǎng)范圍內(nèi)，Al的反射系數(shù)最高，可以減少支架吸收紫外光，使更多的深紫外光可以輸出，所以選用見(jiàn)含Al的DPCLF，圖5-12。圖5-12Au、Al、Ag反射系數(shù)與波長(zhǎng)的關(guān)系結(jié)論本文基于LP-MOCVD技術(shù)探討UVC-LED外延層設(shè)計(jì)，從減少UV-LED有源區(qū)缺陷程度的角度來(lái)改善275nmUV-LED的光電熱特性。實(shí)驗(yàn)結(jié)果顯示UVC-LED得到一定程度的提升。主要實(shí)驗(yàn)結(jié)果如下：使用XRD檢測(cè)①、②、③峰值，實(shí)驗(yàn)結(jié)果顯示①、②、③衍射峰的強(qiáng)度高，F(xiàn)WHM分別為1.026、0.524、0.410Sec-1。說(shuō)明其缺陷密度很小，晶體質(zhì)量很好。在光電特性實(shí)驗(yàn)中，使用電致發(fā)光技術(shù)檢測(cè)整體發(fā)光情況，實(shí)驗(yàn)結(jié)果顯示峰值波長(zhǎng)具有較小的FWHM，并且工作溫度、電流均不會(huì)影響峰值波長(zhǎng)的變化。并且在實(shí)驗(yàn)條件下暫未出現(xiàn)寄生波或者紅移或者藍(lán)移的現(xiàn)象。在光電特性實(shí)驗(yàn)中，LOP實(shí)驗(yàn)結(jié)果說(shuō)明在較大工作電流下，未出現(xiàn)輻射復(fù)合飽和情況。但LOP的斜率拐點(diǎn)與EQE下降拐點(diǎn)均在電流40mA，呈現(xiàn)輻射復(fù)合飽和的趨勢(shì)，側(cè)面驗(yàn)證了位錯(cuò)和雜質(zhì)含量較少；電流大于40mA后，參與非輻射復(fù)合的電子-空穴對(duì)占比逐漸增加。UV-LED的EQE實(shí)驗(yàn)結(jié)果中，最大值為2.37%。說(shuō)明本文探討的LED品質(zhì)屬于世界良好水平，并具有商業(yè)化的可能與價(jià)值。在室溫25℃的熱阻特性測(cè)試中，芯片結(jié)溫達(dá)到70.48℃，芯片、框架、印制電路板、空氣的熱阻值分別為5.53、11.16、4.61、38.54℃/W。存在超過(guò)芯片承載溫度使發(fā)光效率快速降低、損壞芯片的可能。ADDINNE.Bib[參考文獻(xiàn)]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.譚斐,楊映霞.廣西地面太陽(yáng)輻射分布特征以及對(duì)人體健康的影響S14[C]//中國(guó)氣象學(xué)會(huì).中國(guó)氣象學(xué)會(huì),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-StrahlungsquelleninAnalysenger?ten.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.程文進(jìn),鞏小亮,陳峰武,彭立波,魏唯.高溫MOCVD外延生長(zhǎng)AlN材料研究[J].電子工業(yè)專用設(shè)備,2017,46(04):43-49.EsakiL,TsuR.Superlatticeandnegativedifferentialconductivityinsemiconductors[J].IBMJ.Res.Dev.,1970,14(1):61~65ZhangJP,WangHM,GaevskiMEetal.Crack-freethickAlGaNgrownonsapphireusingAIN/AlGaNsuperlatticesforstrainmanagement[J].AppliedPhysicsLetters,20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