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1、VOLUME65,NUMBER8PHYSICALREVIEWLETTERS20AUGUST1990KineticPathwayinStranski-KrastanovGrowthofGeonSi(001)Y.-W.Mo,D.E.Savage,B.S.Swartzentruber,andM.G.LagallyUniversityofWisconsinMadisonM,adison,Wisconsin53706(Received23April1990)Thetransitionfrom2Dto3DgrowthofGeonSi(001)hasbeeninvestigatedwithsca
2、nningtunnelingmicroscopy.Ametastable3Dclusterphasewithwell-definedstructureandshapeisfound.Theclustershaveajl05jfacetstructure.Resultssuggestthattheseclustersdefinethekineticpathforformationof"macroscopic"Geislands.PACSnumbers:68.55.—a,61.16.DiThegrowthofGeonSihasbeenasubjectofintenseminedbyST
3、M,of-0.04'.Thesubstratesarecleanedstudyforseveralyears,drivenbythedesiretocreateSi-byheatingbrieflyto—1525K,whichleavesthemwithaGeheterojunctionsuperlattices,whichwouldformtheverylowdefectdensityandregularlyspacedsteps.Geis'basisofoptoelectronicdevices.Becauseofthe-4%evaporatedfromawaferatasys
4、tempressureoflatticemistnatchbetweenGeandSi,Gegrownon(3x10'oTorr,forseveralsubstratetemperatures.Si(001)growsinalayer-by-layermodeforonlyseveralThesubstrateisquenchedtoroomtemperatureimmedi-layers,afterwhich3Dislandsform.s9Inordertoim-atelyafterdepositionorannealingandtransferredtotheprovethel
5、ikelihoodof2Dlayerformation,theuseofSTM.ThedepositionrateisdeterminedbycountingsurfactantshasbeensuggestedandsomesuccessatomsonSTMimagesofthesurfaceafterasubmono-'achieved.ThissystemisanexampleofStranski-layerofGeisdepositedat-475K,atemperatureatKrastanov(SK)growth,oneofthreebasicgrowthwhichdi
6、ffusionissufficientlyslowsothatonly"anegligi-modespostulatedonthebasisofinterfacethermodynam-bleamountofGeislosttosubstratesteps.Thereisnoics.Ifthelatticeconstantsarenottoodifferentandtheevidence,usingSTM,ofcontaminationmorethan12hsurface"energyofmaterial"A"islargerthanthatofafterinitialsubstr
7、atecleaning."8,8willwetA,formingalayerthatisstrained,untilToinvestigate2DgrowthwedepositedGefrom0.1totheefl'ectsoftheAinterfacearenolongerfelt(typically3monolayers(ML)atavarietyoftemperatures.Sub-onetothreelayers).Aftertheseseverallayer