大功率GaN基LED用SiC衬底刻蚀工艺研究.docx

大功率GaN基LED用SiC衬底刻蚀工艺研究
摘要
本文研究了一种大功率GaN基LED用SiC衬底刻蚀工艺。采用电子束光刻、反应离子刻蚀和化学机械抛光等工艺，成功制备了高质量的GaN基LED器件。通过扫描电子显微镜、X射线衍射和光学测试等手段对样品的表面形貌、结构和光电性能进行了表征。实验结果表明，采用SiC衬底刻蚀工艺能够有效提高GaN基LED的发光效率和可靠性。本研究为GaN基LED的制备提供了一种可行的工艺方法。
关键词：GaN基LED；SiC衬底；刻蚀工艺；发光效率；可靠性
Introduction
Withthedevelopmentofsemiconductortechnology,GaN-basedlight-emittingdiodes(LEDs)havebeenwidelyusedinlighting,backlighting,anddisplayapplicationsduetotheirhighbrightness,highefficiency,andlonglife.However,thefabricationofhigh-qualityGaN-basedLEDsisachallengingtaskduetothelargelatticemismatchandthermalexpansioncoefficientdifferencebetweentheGaNmaterialandthesubstrate.Inrecentyears,researchershavefocusedondevelopingnewsubstratematerialsforGaN-basedLEDstoimprovetheirperformance.
SiCisapromisingsubstratematerialforGaN-basedLEDsduetoitsexcellentthermalconductivity,mechanicalstrength,andchemicalstability.Inaddition,SiChasacloselatticematchwithGaN,whichhelpstoreducelatticedefects.Therefore,SiCsubstrateshavebeenwidelyusedinthefabricationofhigh-performanceGaN-basedoptoelectronicdevices.
However,thefabricationofGaN-basedLEDsonSiCsubstratesalsofaceschallenges,suchasthedifferenceinetchingratesbetweenGaNandSiCandthedifficultyinachievingahigh-qualityinterfacebetweenGaNandSiC.Inthisstudy,weinvestigateanewetchingprocessforcreatinghigh-qualityGaN-basedLEDsonSiCsubstrates.
ExperimentalProcedure
TheexperimentalprocedureforfabricatingGaN-basedLEDsonSiCsubstratesisdescribedbelow.
1.PreparationofSiCSubstrates
4-inchn-typeSiCwaferswitha4Hcrystalstructurewereusedassubstrates.TheSiCwaferswerecleanedinaultrasonicbathandthenannealedinanitrogenatmosphereat1300℃for30minutestoremoveimpurities.
2.EpitaxialGrowthofGaNLayers
GaNlayersweregrownontheSiCsubstratesbymetal-organicchemicalvapordeposition(MOCVD).Trimethylgallium(TMGa)andammonia(NH3)wereusedasthesourcegases.Thegrowthtemperaturewas1030℃andthepressurewas300Torr.Thegrowthratewasabout2μm/h.
3.DeviceFabrication
AftertheGaNlayersweregrown,thesampleswerepatternedbyelectronbeamlithography(EBL)andt