首页 【doc】 由ZnO胶体球生长光子晶体(英文)

【doc】 由ZnO胶体球生长光子晶体(英文)

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【doc】 由ZnO胶体球生长光子晶体(英文)【doc】 由ZnO胶体球生长光子晶体(英文) 由ZnO胶体球生长光子晶体(英文) :H?049026756(2005)0z220183204 ?A?K???l:2005208231 ????????????3????(53Z2);???????A????????(633) ???6?????F?l,??,?????;????,?????h???l 3,2@ PhotonicCrystalsGrowthFromZnOColloidalSpheres XIEJuan 3 ,DENGHong,XUZ...

【doc】 由ZnO胶体球生长光子晶体(英文)
【doc】 由ZnO胶体球生长光子晶体(英文) 由ZnO胶体球生长光子晶体(英文) :H?049026756(2005)0z220183204 ?A?K???l:2005208231 ????????????3????(53Z2);???????A????????(633) ???6?????F?l,??,?????;????,?????h???l 3,2@ PhotonicCrystalsGrowthFromZnOColloidalSpheres XIEJuan 3 ,DENGHong,XUZi2qiang,LIYan,HUANGJun (SchoolofMicroelectronicsandSolidStateElectronics,UniversityofElectronic ScienceandTechnologyofChina,Chengdu610054,China) Abstract:AnovelmethodforthesynthesisofmonodisperseZnOcolloidalspheresispresented. Thesesphereswereself2assembledintophotoniccrystals.Themicrostructureswerecharacterized bythescanningelectronmicroscope.Theresultsshowthatthephotoniccrystalsexhibitaclear bandgapinspecularreflectivitymeasurements.Thepositionoftheobservedr eflectancepeak scalesremarkablywellwiththediameterofthespheres,indicatingtherewasanintrinsicfeature ofthephotoniccrystals.Thepositionsofthebandgapareshiftedtotheshorterwavelengthwith decreaseofZnOparticlessize. Keywords:zincoxide;photoniccrystals;colloidalspheres;self2assembly;blue2shift CLCnumber:TN304.2+ 1H?H?H?Documentcode:A 1H?Introduction Recently,photoniccrystals(PCs)haveattractedmuchattentionfrombothfundamentalandpractical pointsofview[1] .PCsareperiodicdielectricstructuresdesignedtocontrolthepropagationofelectromagnetic (EM)wavesbydefiningallowedandforbiddenenergybandsinthephotondispersionspectrum[2] .Oneofthe characteristicpropertiesofPCsisthepresenceofaPBG.AtthePBGwavelength,propagationofphotonsis inhibitedinsidethePCstructure.Thisopensintriguingperspectivesinphoton icapplicationslikeopticalfibers orhighbendinganglewaveguides[3] .However,itisagreatchallengetofabricatethesePCswithaPBGat opticalandnear2infraredfrequencies,andtoshowasignificanteffectonthespontaneousemissionrate.Nu2 meroustechniqueshavebeendevisedinanefforttoproducetheseperiodicarrays [4] .Manytechniqueshave beenusedtofabricatePCs,suchaslithography,top2downGcapproach.However,theseapproachesarerela2 tivelyexpensiveandtime2consumingprocesses.Incontrast,chemicalassemblyofordereddielectricsprovides asimplerandlesscostlyapproachtogeneratinglarge2scalePCs.Thesetechniquesmakeuseofthespontaneous assemblyofsubmicronparticlesintospecificwell2orderedlatticestructures [5] .ZnOisanimportantwide2 bandgapsemiconductormaterial,whichhasahigherrefractiveindex(2.1??2.2inthevisibleregime)than othermaterials(1.4??1.5forSiO2andmostpolymers).Therefore,ZnOisanotherpromisingcandidatefor opticallyactiveself2assembledphotoniccrystals.However,littleresearchhasreportedonZnOPCs [6] . H?H?Inthispaper,anovelmethodforsynthesisofZnOcolloidalspheresispresented.Inaddition,wehave proposedatunablePC,inwhichthePBGcanbetunedasdesiredbycontrollingparameterssuchasZnOcol2 2005??10?( ?J42?????)2 ?????p??????(???A?????-) JournalofSichuanUniversity(NaturalScienceEdition) Oct.2005 Vol.42H?Issue2 :9711009409007 :. Email:hdenguestc.edu.cn. loidalspheressize.ThereflectancespectraofthePCshiftsystematicallywiththespheressize,providingevi2 denceofphotoniccrystaleffects. 2H?Experimental ThemethodofsynthesisZnOcolloidalspheresinvolvestwosteps.Inaprimar yreaction,zincacetatede2 hydrate(ZnAc,0.02mol.)wasaddedinto150mLdiethyleneglycol(DEG).Thisreactionsolutionwas heatedunder180w4.Afterreachingtheworkingtemperature,precipitationofZnOspheresoccurred.Thein2 termediateproductwasplacedinacentrifuge.Thepolydispersepowderwasdiscardedandthesupernatant (DEG,dissolvedreactionproducts,andunreactedZnAcandwater)wasusedinthesecondstep.Asecondary reactionwasthenperformedtoproducethemonodisperseZnOspheres,whichbeganinthesamewayasapri2 maryreaction.ZnAc(0.02mol.)wasaddedinto150mLDEGandthereactionsolutionwasheatedunderre2 flux.Priortoreachingtheworkingtemperature(at170w4),differentvolumeoftheprimaryreactionsuper2 natantwasaddedintothesolution,3mL,5mL,8mL,10mL,15mL,20mL,respectively.Following thisaddition,therewasatemperaturedrop,andprecipitationwouldtypicallyoccuratalowertemperature thanwithoutsuchanaddition.Afterreaching180w4,thereactionwasstirredforonehour.ThentheZnO colloidalsuspensionwasprepared.ThesizeoftheZnOcolloidalsphereswere controlledbyvaryingtheamount ofsupernatantadded. H?H?PhotoniccrystalswereproducedfromtheZnOcolloidalspheresusingaself2assemblysedimentationpro2 cess.Thereactionsolutionwasdroppedontoaglasssubstrateattemperature,rangedfrom30w4to300w4, andasthesolventevaporated,theparticlesspontaneouslyassembledintoperiodicarrayswithdifferentparticle sizes. ThesurfaceoftheZnOPCswasobservedwiththescanningelectronmicroscope(SEM,JSM25900LV) andtheopticalpropertieswereanalyzedbyUV2VIS2NIRdoublebeamspectrophotometer(UV22550,SHI2 MADZU). 3H?Resultsanddiscussion TheSEMimagesinFig.1revealthattheorderedstructuresofZnOsynthesizedusingthistechnique. Andthesizeofthecolloidalspheresvariesinverselyandmonotonicallywiththeamountofprimarysuper2 natantadded.TheSEMimagesindicatethatthecolloidalspheresinthefilmarehighlyorientedwiththe FH?SMfZOy 2fx22 yyTfyy 481?????p??????(???A?????-)?J42?? ig.1Emicrographsonphotoniccrstal closepackedplanesparalleltothesubstrate.Preerentialorientationalsoeistsintheclosepackedplaneprob ablduetostressesdevelopingduringthedringprocess.hisalignmentocolloidalspheresmaprovever usefulforapplicationsandmeasurementsespeciallyincaseswhereafullphotonicbandgapdoesnotexistinall directionsofpropagationinthecrystal. ThemajoropticalsignatureofZnOPCsisfoundinreflectancemeasurements.Thespecularreflectanceat near2normalincidencefromourorderedstructuresisshown[Fig.2]fordifferentsizesofcolloidalspheres. TheinitialspheresizesweremeasureddirectlyfromSEMimagesoftheorderedstructuresofZnOspheres. Theprominentfeatureisaspecularreflectivitypeakforeachstructure,whichsystematicallyshiftsfrom 400to900nmovertherangeofphotoniccrystals.Thewavelengthofthespecularpeakcorrespondsverywell tothesizeofZnOcolloidalspheres.Thewavelengthsofthereflectivitypeaksc overtheentirevisiblespectrum andextendwellintothenearinfraredspectrum.Inaddition,thereisagradualbutfeaturelessincreaseinre2 flectivityatlongerwavelengthsinseveralsamples[Fig.2].ThisisduetotheroughsurfaceofthePCGcsap2 pearingsmootherwhenprobedatlongerwavelengths.Thisincreasesthespecularreflectivity,withanaccom2 panyingdecreaseofthediffusereflectanceatlongerwavelengths. Fig.2H?TransmissionspectraforperiodiclayersofZnOspheresofvarioussizes Thepositionoftheobservedreflectivitypeakscalesremarkablywellwiththediameterofthespheres [Fig.3],indicatingthatitisanintrinsicfeatureofthephotoniccrystals.Withthedecreaseofthesizeofcol2 loidalspheres,thereflectancespectraofthesesorderedstructuresblueshift.Thisisanobservationoftheop2 ticalsignatureofaphotoniccrystaltogetherwiththerequiredscalingwithspheresize,whichhasbeenseenin sometypicalPClikepolystyrene[7] . 4H?Conclusion Thesuccessinthegrowthoflarge2areaZnOopticalphotoniccrystalsusingra pid,economical,andsimple techniqueswillopenthewaytowardstheexperimentalobservationofmanyinterestingeffectsinvolvingthe controloflightemissionandpropagationinthesematerials.Thespecularreflectanceexperimentsyieldedor2 deredcrystallinestructure.Itisfoundthatwiththedecreaseofthesizeofcolloidalspheres,thereflectance spectraofthesesorderedstructuresblueshift. Acknowledgements TheauthorswishtothanktheChineseNatureScienceFundamentalCommittee(60390073)andNation2 BRf(53Z)ff 581???)2?F?l?/:?gZnO?????4?l???/?????? alasicesearchProgramoChina11009orinancialsupport. References: [1]H?ChabanovAA,JunY,NorrisDJ.Avoidingcracksinself2assembledphotonicband2gapcrystals[J].Appl.Phys.Lett, 2004,84(18):3573-3575. [2]H?AlexanderS,AlexanderV,KontGcko,etal.Silicaphotoniccrystals:synthesisandopticalproperties[J].SolidStateIonics, 2004,172:477-479. [3]H?SinitskiiAS,KnotkoAV,TretyakovYD.Silicaphotoniccrystals:synth esisandopticalproperties[J].SolidStateIonics, 2004,172:477-479. [4]H?SeeligEW,TangB,CaoH,etal.Self2assembled3DphotoniccrystalsfromZnOcolloidalspheres.Mater.Chem.Phys, 2003,80:257-263. [5]H?ChangX,CaoJ,etal.Solvothermalsynthesisof3DphotoniccrystalsbasedonZnS/opalsystem[JHn.Mater.Chem.Phys, 2005,89:6-10. [6]H?ScharrerM,WuX,YamilovA,CaoH,ChangRPH.FabricationofinvertedopalZnOphotoniccrystalsbyatomiclayer deposition[J].Appl.Phys.Lett,2005,86:151113. [7]H?ChungYW,LeuIC,LeeJH,HonMH.Fabricationandcharacterizationofphotoniccrystalsfromcolloidalprocesses[J]. J.Cryst.Growth,2005,275:2389-2394. ?gZnO?????4?l???/?????? ?F?l3 ,????,?????T,????,???r (?Y???????p?????Y???3?????Y??????,?;??610054) ????:?X?e?????T?z????????,?7???7????ZnO?????????????????????T?2???/??????.?C???????Y???? ?gH:???9?/?g???A????ZnO?/????????????????.???????3,?????????????H???n?2?????/??????,???h ?v?????????????????AZnO?????4???T??.?A?????f???2?3?k???/?????S ,?h???S???????????????4?? ???????Z?1????,???N?/????????????????. ???D??:ZnO?/??????;?????4;??????;???? ?u???7????:TN304.2 + 1H?H?H????D?5???::A 681?????p??????(???A?????-)?J42??
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