简介:ThepurecubicGaN(c-GaN)hasbeengrownon(001)GaAssubstratesbyECR-PAMOCVDtechniqueatlowtemperatureusingTMGaandhighpureN2asGaandNsources,respectively.TheeffectsofsubstratepretreatmentconditionsonqualityofcubicGaNepilayerareinvestigatedbythemeasurementsofTEMandXRD.Itisfoundthathydrogenplasmacleaning,nitridationandbufferlayergrowthareveryimportantforqualityofcubicGaNepilayer.
简介:Byusingspectroscopicphotoconductance,transmittanceandluminescencemethods,theopticalcharacterizationofGaNgrownbyplasmasourceMBEhavebeenevaluated.Theimperfectionoftheepitaxiallayerdeducedfromthemeasuredresultshavebeendiscussed.Thetransientresponsesofthephotoconductivedetectorshavebeenmeasured.Twotimeconstantsof0.17msand6.85msatroomtemperaturearededucedfromthemeasuredresults.Theoriginshavealsobeendiscussed.
简介:Measurementsoftheexcitationpower-dependenceandtemperature-dependencephotoluminescence(PL)areperformedtoinvestigatetheemissionmechanismsofInGaN/GaNquantumwells(QWs)inlaserdiodestructures.ThePLspectralpeakisblueshiftedwithincreasingtemperatureoveracertaintemperaturerange.ItisfoundthattheblueshiftrangewaslargerwhenthePLexcitationpowerissmaller.ThisparticularbehaviorindicatesthatcarriersarethermallyactivatedfromlocalizedstatesandpartiallyscreenthepiezoelectricfieldpresentintheQWs.Thesmallblueshiftrangecorrespondstoaweakquantum-confinedStarkeffect(QCSE)andarelativelyhighinternalquantumefficiency(IQE)oftheQWs.
简介:TheenergybanddiagramandchargedistributionoftheunintentionaldopedAIGaN/GaN/AIGaN/GaNdoubleheterostructurewereobtainedbyself-consistentPoissonSchroedingercalculations.Theseverebandtiltingandhightwo-dimensionalelectrongas(2DEG)densitymainlyattributetothelargeinternalpolarizationintensity,whichisc/osetoalinearfunctionorAlcomposition.TheinfluenceorAlcompositionisinvestigated.Theresultsshowthatbandtiltingenlargesand2DEGgainswithAIcomposition,andtwo-dimensionalholegasoccurswhenAIcompositionreachesacertainextent.TheinfluenceorAlcompositionandtwo-dimensionalholegas(2DHG)ondevicesisdiscussed.