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1、第35卷第5期發(fā)光學報V01.35No.52014年5月CHINESEJOURNAL0FLUMINESCENCEMay,2014文章編號:1000-7032(2014)05-0595-05GaN基LED低溫空穴注入層的MOCVD生長研究黃華茂,游瑜婷,王洪+,楊光(華南理工大學理學院物理系廣東省光電工程技術(shù)研究開發(fā)中心,廣東廣州510640)摘要:針對GaN基LED空穴注入效率低的問題,在量子阱與電子阻擋層之間插入低溫空穴注入層(LT—HIL),實驗研究了MOCVD生長LT.HIL時二茂鎂(cp:Mg)流量和生長溫度的影響。結(jié)果表明:隨著cp:
2、Mg流量的增加,外延薄膜晶體質(zhì)量下降,外延片表面平整度和均勻性降低;而受Mg摻雜時補償效應的影響,主波長先紅移后藍移。芯片的輸出光功率先升高后降低,正向電壓先降低后升高。相比于無LT.HIL的樣品,在20·ln工作電流下,cp,Mg流量為1.94I山mol/min時制備的芯片的輸出光功率提升20.3%,而正向電壓降低O.1v。在cp:Mg流量較大時,LT.HIL的漸變式生長溫度對外延質(zhì)量有所改善,但不是主要影響因素。關(guān)鍵詞:LED;MOCVD;低溫空穴注入層;二茂鎂;溫度中圖分類號:TN303:TN304文獻標識碼:ADOI:10.3788/f
3、gxb20143505.0595InvestigationofLowTemperatureHole-injectionLayerinGaN-basedLEDEpitaxialWaferGrownbyMOCVDHUANGHua—mao,YOUYu-ting,WANGHong+,YANGGuang(EngineeringResearchCenterforOptoelectronicsofGuangdongPr∞ince.DepartmentofPhysics,SchoolofScience,SouthChinaUniversityofTechnol
4、ogy,Guangzhou510640,China)}CorrespondingAuthor,E—mail:phhwang@scut.edu.cnAbstract:Alow—temperaturehole—injectionlayer(LT-HIL)wasinsertedbetweenmultiple—quantumwellandelectron-blockinglayerinGaN-basedthehole—in-light—emittingdiodes(LEDs)toimprovejectionefficiency.Theeffectsof
5、magnesocene(Cp2Mg)flowrateandprocesstemperatureofLT—HILinMOCVDepitaxywereinvestigated.Thesurfacereflectivityanddominantwavelengthofepi-taxialwafersweremeasuredbyphotoluminescencespectrometer,thesurfaceprofileswereobservedbymicroscope,andthelight-outputpowerandforwardvoltageo
6、ffabricatedchipsweretestedbywa·fer—levelauto-measurementsystem.AstheCp2Mgflowrateincreases,thecrystalquality,flatness,anduniformityofepilayerdecrease.DuetothecompensationeffectsinMg—dopedGaNmaterial,thedominantwavelengthshowsred—shiftatfirstandthenblue—shift,theoutputpowerof
7、thechipgoesuptothemaximumthenfallsdown,andtheforwardvoltagegoesdowntotheminimumthenrisesup.ComparedtoconventionalLEDchipswithoutLT—HIL,theoutputpowerandforwardvoltageoftheLEDchipswithCp2Mgmoralflowrateof1.94Ixmol/minareenhancedby20.3%andreducedby0.1Vundertheinjectioncurrento
8、f20mA.Itisalsoshownthatthegraduallychangingprocesstemperaturecanalsoimprove