Fabrication of nanomaterials using anodic aluminum oxide and

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CurrentAppliedPhysics11(2011)S339eS345

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CurrentAppliedPhysics

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Fabricationofnanomaterialsusinganodicaluminumoxideandtheirproperties

Hyun-MinYu,JaehyeongLee*

DepartmentofElectronicEngineering,KunsanNationalUniversity,Kunsan,San68,Miryong-dong,Jeollabuk-do573-701,RepublicofKorea

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Articlehistory:

Received7September2010Receivedinrevisedform29November2010

Accepted29November2010

Availableonline4December2010Keywords:

Chemicalbathdeposition(CBD)Anodicaluminumoxide(AAO)Cadmiumsul de(CdS)Nanomaterials

abstract

Aporousanodicaluminumoxide(AAO)templateonthealuminumplatewasformedbytwo-stepanod-ization.Verticallywellalignedporeshadtheaverageporesizesof15e70nmandthelengthofapproxi-mately40mm.CdSnanostructurematerialshavebeenfabricatedinporousanodicaluminumoxide(AAO)templatebyusingchemicalbathdeposition(CBD).Thesenanostructurematerialshaduniformdiametersofabout15e200nm,whichcorrespondtotheporesizesofthetemplatesused,andthelengthwasupto40mm.X-raydiffraction(XRD)investigationdemonstratesthatCdSnanostructurematerialswerehexagonalpolycrystallineinnature.AstheporediameterofAAOtemplateswasenlarged,thepreferentialorientationofc-axiswasimproved.FromPLanalysis,thesulfur-de cientdefectsatthesurfacesofCdSnanostructurematerialswereincreasedwhenthesamplewassynthesizedinthetemplatewithlargerporediameter.

Ó2010ElsevierB.V.Allrightsreserved.

1.Introduction

One-dimensionalsemiconductornanostructurematerialshaveattractedconsiderableattentionbecauseoftheiruniquepropertiesaswellastheirpotentiallywideapplicationsinelectronic,opticalstructuresanddevices[1e9].ItiswellknownthatCdSisatypicalwidebandgapIIeVIsemiconductorhavingabandgap2.42eVatroomtemperature.CdShasmanycommercialorpotentialappli-cationsinlight-emittingdiodes,solarcells,orotherphotoelectricdevices.Duetoitsuniformandnearlyparallelporousstructure,porousanodicaluminumoxide(AAO)hasbecomeanidealtemplateforpreparationofmanysemiconductorsnanostructurearrays.ThenanostructureofCdS,CdSe,CdTe,GaN,andZnOcanbefabricatedbyvariousmethods,suchastheelectro-deposition,chemicalvapordeposition(CVD),andchemicalsolutiontransport(CST)[10e17].Comparedwiththesetechniques,chemicalbathdeposition(CBD)hastheadvantagesofsimplicity,highef ciencyandlowcost.Moreover,CBDisawellprovedprocessforthepreparationofCdS lms[18e24].

Inthispaper,wehavesynthesizedtheCdSnanostructurematerialsusingchemicalbathdeposition(CBD)intheAAOtemplate.Thebasicideaofthismethodis,ononehand,tomakethenano-sizedporesinAAOtemplateforthecon nementofgrowthofnanostructurematerialsacrossthediameter,ontheotherhand,totakeadvantageoftheorderlyporesintheAAOtemplateforthedirectionalgrowthofCdSnanostructurematerialsalongthelength.

2.Experimentaldetails

Anodicaluminumoxidelayerwasgrownonthehigh-purityaluminumplate(0.5mmthick,99.99%).Priortoanodizing,theAlplateswereelectropolishedtomakeamirror nishina4:1v/vsolutionofethylalcohol(95%)/HClO4(70%)at20Vand7 Cfor2e3min.Toincreasetheorderingqualityoftheporousstructure,AAOtemplateswerepreparedbyatwo-stepanodizingprocessasdescribeddetailelsewhere[25e27].Firstly,AlplatewasanodizedinanacidelectrolytewithPtcounterelectrodes.Theanodizationtemperaturewas5 Cforsulfuricacid(1.2M)and15 Cforoxalicacid(1.2M),respectively.Theanodizationvoltageandtimewere15e50Vand1h.Theporousanodicoxidelayer,whichhasadisorderstructure,wasetchedinamixtureofphosphoricacid(6wt%)andchromicacid(1.8wt%)for2h.Afterthisremoval,thetexturedAlplatewasanodizedagainfor7e14hundertheidenticalconditionsto rstanodizationstep.Thewideningprocessaftersecondanodizationwascarriedoutinphosphoricacid(0.1M)at30 Cfor10e60min.BecausethediametersofporesinAAOlayerintheourworkwereintherangeof15e80nm,thecommerciallyavailableporousaluminamembranes(Anodisc25,Whatman)whichcontainuniformchannels(w200nmindiameter)wereusedfortheAAOtemplatewithporesizeover100nm.

CdSnanostructurematerialsweredepositedintotheAAOtemplatebyreacting0.025MCd(CH3COO),0.1M(NH2)2CSand0.1MNH4(CH3COO)inanaqueoussolution.ThepHofthesolutionwasadjustedto11usingammonia.Thereactiontemperatureandtimewere75 Cand25min,respectively.Afterdeposition,thenanostructurematerialsintheAAOtemplateswereultrasonicallycleaned,andthendried.Foranalysis,theas-preparedsampleswere

*Correspondingauthor.Tel.:þ82634694707;fax:þ82634694699.E-mailaddress:jhyi@kunsan.ac.kr(J.

Lee).1567-1739/$eseefrontmatterÓ2010ElsevierB.V.Allrightsreserved.doi:10.1016/j.cap.2010.11.083

期刊文章

S340H.-M.Yu,J.Lee/CurrentAppliedPhysics11(2011)S339eS345

Fig.1.Surfacemicrographsofas-preparedAAO lmsandporousaluminamembranewithdifferentporediameters:(a)15nm,(b)30nm,(c)50nm,(d)70nmand(e)200nm.

etchedslightlytoremovethethickCdSlayercoveredontheAAOtemplate.

ThecrystalstructureofCdSnanostructurematerialsincorporatedintheAAOtemplateswascharacterizedbyanX-raydiffraction(XRD)measurementinthe2qmode.ThemorphologyoftheCdSnano-materialswasexaminedbyFieldEffectScanningElectronMicros-copy(FE-SEM).RamananalysiswasperformedatroomtemperatureusingaNanoRamanSpectroscopy(NTEGRA)with532nmexcitationsourcefromanArþlaser.Thephotoluminescence(PL)measurementsarecarriedoutonaspectrometer(REF-1052M-4K5W).3.Resultsanddiscussion

Fig.1showsthesurfacemicrographsofas-preparedAAOtemplatesandporousmembranewithdifferentporesizes.ThesurfacemorphologiesofAAOtemplateexhibithexagonalpackedporeswiththeaverageporediameterintherangeof15e200nm.Across-sectionalviewofthecleavedtemplateinFig.2showsthatthenanochannelsarehighlyordered,paralleltoeachotherandhavesmoothinnerwallsaswellasuniformdiameters.Thelengthofporeswasabout40mmafterthetwo-stepanodization.Thedifferentporediametersareneededdependingonwhethercarbonnanotubes(CNTs)orsemiconductornanowires(NWs)areofconcern.Theporediametersinthe3nmrangeareinterestingfortemplatingCNTs,whereasforsemiconductorNWs,therangeofdiameterscan …… 此处隐藏：6464字，全部文档内容请下载后查看。喜欢就下载吧 ……