6533b858fe1ef96bd12b5754

RESEARCH PRODUCT

Study of inversion domain pyramids formed during the GaN:Mg growth

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AbstractThestudyofstructuraldefectsinducedbytheintroductionofMgduringthegrowthofMOCVDGaNispresented.Themagnesiumincorporationintothecrystalgrowthnotonlyinduceschangesinthestackingsequencefromhex-agonaltocubicstructures,butalsoinvertstheGaNpolarityfromGa-facetoN-face.Basedonthedifferentsurfacestructureandsurfacemigrationlengthofabsorbingprecursorsforeachpolaritytype(Ga-orN-face),the3DgrowthontopoftheN-facetriangulardefectisdescribed.TheN-facematerialischaracterizedbythreedanglingbondsofni-trogenthatpointuptowardthec-planesurface,enhancingthecrystalgrowthalongthec-axis. 2002ElsevierScienceLtd.Allrightsreserved. Keywords:Inversiondomain;Stackingfault;Polarity 1. IntroductionFurther progress towards advanced optoelectronicdevicesrequiresabetterunderstandingoftheimpurityincorporation, defect formation, and recombinationprocessesinGaNepilayers.Difficultieswithp-dopingofGaNhasslowedthedevelopmentofGaNtechnologyanddelayedtheapplicationofthismaterialinopto-electronic devices. Magnesium is the best candidateamong all possible dopants to obtain p-doping, butthermalannealingneedstobeappliedtodissociateMg–HcomplexesandactivatetheMgatoms[1].Despitetheseproblems,blueLEDshavereachedthecommercialmarket,andsomeCWlasersnowadayshavealifetimeofthousandsofhours[2].However,completeunder-standingofthebehaviorofthisdopantisstillnotsat-isfactory.Thelifetimeoftheseopticaldevicesiscriticallydeterminedbytypicaldefectssuchasstackingfaults,inversiondomain(ID)boundaries,threadingandmisfitdislocations,whichcanactastrapsandrecombinationcenters.Thisisprobablythereasonwhysofewresearchgroupshavebeenabletoproducelaserswithsufficientlylongworkinglifetimes.Inordertoinvestigatethefor-mationofsomestructuraldefectstypicalofMg-dopedGaN films, in this work we present the study ofMOCVDgrownGaNsampleswithMgdopingcon-centrationrangingfrom10