Fabrication of nanomaterials using anodic aluminum oxide and

期刊文章

CurrentAppliedPhysics11(2011)S339eS345

ContentslistsavailableatScienceDirect

CurrentAppliedPhysics

journalhomepage:/lo

cate/cap

Fabricationofnanomaterialsusinganodicaluminumoxideandtheirproperties

Hyun-MinYu,JaehyeongLee*

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

articleinfo

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,therangeofdiameterscanspreadbetween10and100nm[28].Inpresentwork,AAOtemplateswithdesiredporediametercouldbefabricatedbycontrollingelectrolyte,anodizationvoltage,andwideningtime,asseenFigs.1and2.

Figs.3and4showthesurfaceandcross-sectionalSEMimagesofCdSnanomaterialsembeddedinAAOtemplatesandporousaluminamembranes.ThedepositionofCdSnanomaterialsintotheporesofAAOtemplatesiscomplicatedbysidereactions

involving

期刊文章

H.-M.Yu,J.Lee/CurrentAppliedPhysics11(2011)S339eS345S341

Fig.2.Cross-sectionalSEMimagesofas-preparedAAO lmsandporousaluminamembranewithdifferentporediameters:(a)15nm,(b)30nm,(c)50nm,(d)70nmand(e)200nm.

期刊文章

S342H.-M.Yu,J.Lee/CurrentAppliedPhysics11(2011)S339eS345

Fig.3.SurfacemicrographsofCdSnanostructurematerialsembeddedinAAOtemplateonAlplatesandporousaluminamembrane:(a)15nm,(b)30nm,(c)50nm,(d)70nmand(e)200nm.

期刊文章

H.-M.Yu,J.Lee/CurrentAppliedPhysics11(2011)S339eS345S343

Fig.4.Cross-sectionalSEMimagesofCdSnanostructurematerialsembeddedinAAOtemplateonAlplatesandporousaluminamembrane:(a)15nm,(b)30nm,(c)50nm,(d)70nmand(e)200nm.

theAAOsuchasreanodization,dissolution,andAlcorrosionwhichcanevenresultinthedestructionoftheporoustemplate.FE-SEMmicrographsofnanostructurematerialsinthetemplateshowthatthedepositedsemiconductor,indeed, llstheporesuniformlyandthatthenanostructurematerialsareapparentlycontinuous.Inaddition,thedirectionalgrowthofCdSnanostructurematerialswasfound,becauseofthecon nedgrowthofthenanostructurematerialsintheorderlyporesofanAAOtemplateoraluminamembrane.ThemeasureddiameteroftheCdSnanostructurematerialscorrespondedcloselytotheporediameter.

Fig.5showstheXRDpatternsfortheCdSnanostructuremate-rialsembeddedintheAAOtemplateandaluminamembrane.Fortheporediameterof15nm,twopeaksrelatedtoCdSareobservedat2q¼26.3 and47.7 .Thesepeaksareattributedtothe(002)and(103)planesofwurtzitehexagonalphase.Guduruetal.[29]reportedthatthepresenceofcrystalorientationsotherthanthec-axisorientationcanbedetrimentaltotheoveralldeviceperfor-manceindiodespreparedwiththis lm.Nootherdiffractionpeaks,suchasCdO,Cd,S,orAl2O3,weredetectedinthesamples,sug-gestingthattheCdSnanomaterialsarehigh-puritycrystallineCdS.Inaddition,threepeakscorrespondingto(111),(200),and(220)planesofcubicphasealuminumareshowninXRDpatterns.Sincetheanodizationconvertsthetopportionofthealuminumsheet(500mmthick)intonanoporousaluminumoxide,thesealuminumpeaksexhibitintheXRDpatterns.AstheporediameterofAAOtemplatesislarger,therelativelyintensityof(002)peakisincreased,indicatingthatthepreferentialgrowthdirectionofc-axisisimproved.Forporesizeof200nm,however,theXRDpeaksofCdSnanomaterialsbecameweaker.ThereasonforweakdiffractionpeaksisderivedfromthatCdSnanostructurematerialsdepositedontheporousaluminamembraneisnotcoveredonitssurfacebyexcess

etching.

期刊文章

Fig.6showsthetypicalRamanspectrumoftheCdSnanostructurematerials.BecauseRamanscatteringisverysensitivetothemicro-structureofnanocrystallinematerials,itisalsousedheretoclarifythecrystallinityoftheCdSnanostructurematerials.TheRamanpeakslocatedataround303,and602cmÀ1correspondto rst-andsecond-orderlongitudinalopticalphononmodesofCdS,respectively.Thepeakpositionsareanalogoustothose(303and604cmÀ1)ofsinglecrystallineCdS[30],indicatingthattheCdSnanostructurematerialshaveasimilarcrystalstructureofthebulkCdS.

Thephotoluminescence(PL)oftheCdSnanomaterialssynthe-sizedintheAAOtemplateandporousaluminamembraneisshowninFig.7.TheCdSnanomaterialembeddedinAAOtemplatewith15nmporesizedidn’texhibitanyPLpeakduetosmallamountofCdSnanomaterialsobtainedfromthedissolvedsolution.Allsamples

Fig.7.PLspectraoftheCdSnanomaterialssynthesizedintheAAOtemplateandporousaluminamembranewithvariousporediameters.ThePLspectraweremeasuredat5Kandthewavelengthoftheexcitationlaserwas531

nm.

haveabroadpeakbetween525nmand570nm(correspondingto2.36eVand2.18eV).Inpolycrystallinesystems,thePLemissionlinesarenotsharppeaksbutarebroadbandbecauseofthepresenceofmanyrecombinationsites[31].Fromthesespectra,agreenbandfor30nmporesizeisobservedat2.36eV.Thegreenemissionbandscorrespondingtoa2.3eVwereattributedintheliteraturetothetransitionofsulfurvacancy(VS)tothevalencebandandthedonoreacceptorpairsrecombination[32,33].Theshiftofthepeak(noworangeemissionat2.18eV)andthehigherpeakintensityareobservedwhenthesampleissynthesizedinthetemplatewithlargerporediameter,suggestingthatthesulfur-de cientdefectsatthesurfacesofCdSnanostructurematerialsisincreased.SincethisCdSnanomaterialsarefabricatedonthebasisoftheAAOtemplatewithorderedarrangementofthenanopores,thiskindoftemplatewillbeusefulinfabricatingAl-basednanoscaledlightssource.

4.Conclusions

Insummary,wehavesynthesizedthehexagonalCdSnanostructurematerialsintheAAOtemplatesusingchemicalbathdeposition.Theas-preparedCdSnanostructurematerialswith15e200nmintheporesizeand40mminlengthhavebeencharacterizedbyFE-SEM,XRD,Raman,andPLspectrum.TheXRDpatternoftheembeddedCdSnanomaterialsindicatedthehexagonallatticewiththedominantcrystalorientationsof<002>and<103>.Itwasfoundthatthepreferentialgrowthofc-axiswasimprovedastheporediameterwaslarger.Furthermore,CBDmethodisalsobelievedtobeappropriateforthegrowthofothersemiconductornanostructurematerials,andpreparationofmanylow-dimensionalnanomaterialssuchasnanodotsand

nanotubes.

期刊文章

H.-M.Yu,J.Lee/CurrentAppliedPhysics11(2011)S339eS345S345

Acknowledgements

ThisworkwassupportedbytheKoreaResearchFoundation(KRF)grantfundedbytheKoreagovernment(MEST)(No.2010-0015850).References

[1]S.Iijima,Nature354(1991)56e58.

[2]H.Dai,E.W.Wang,Y.Z.Lu,S.Fan,C.M.Lieber,Nature375(1995)769e772.[3]W.Han,S.Fan,Q.Li,Y.Hu,Science277(1997)1287e1289.

[4]J.R.Heath,F.K.LeGoues,Chem.Phys.Lett.208(1993)263e268.

[5]Z.F.Ren,Z.P.Huang,J.W.Xu,J.H.Wang,P.Bush,M.P.Siegal,P.N.Provencio,Science282(1998)1105e1107.

[6]M.S.Fuhrer,J.Nygard,L.Shih,M.Forero,Young-GuiYoon,M.S.C.Mazzoni,HyoungJoonChoi,Science288(2000)494e497.

[7]J.Kong,N.R.Franklin,C.Zhou,M.G.Chapline,S.Peng,K.Cho,H.Dai,Science287(2000)622e625.

[8]J.Hone,B.Batlogg,Z.Benes,A.T.Johnson,J.E.Fischer,Science289(2000)1730e1733.

[9]X.Duan,C.M.Lieber,Adv.Mater.12(2000)298e302.

[10]H.I.Liu,N.I.Maluf,R.F.Pease,J.Vac.Sci.Technol.B10(1992)2846e2850.[11]T.Ono,H.Saitoh,M.Esashi,Appl.Phys.Lett.70(1997)1852e1854.

[12]S.Hu,A.Hamidi,S.Altmeyer,T.Koster,B.Spangenberg,H.Kurz,J.Vac.Sci.Technol.B16(1999)2822e2824.

[13]M.Andersson,A.Iline,F.Stietz,F.Trager,Appl.Phys.AMater.Sci.Proc.68(1999)609e614.

[14]

G.Palasantzas,B.Ilge,J.DeNijs,L.J.Geerligs,J.Appl.Phys.85(1999)1907e1910.

[15]K.Hiruma,M.Yazawa,T.Katsuyama,K.Okawa,K.Haraguchi,M.Kogucchi,

H.Kakibayashi,J.Appl.Phys.77(1995)477e482.

[16]W.Q.Han,S.S.Fan,Q.Q.Li,Y.D.Hu,Science277(1997)1278e1289.[17]C.R.Martin,Science266(1994)1961e1966.

[18]G.Sasikala,P.Thilakan,C.Subramanian,Sol.EnergyMater.Sol.Cells62(2000)

275e293.

[19]J.G.Vazquez-Luna,R.B.LopezFlores,M.Rubin-Falfan,L.Del,C.Gomez-Pavon,

J.CrystalGrowth187(1998)380e386.

[20]I.O.Oladeji,L.Chow,J.R.Liu,W.K.Chu,A.N.P.Bustamante,C.Fredricksen,

A.F.Schulte,ThinSolidFilms359(2000)154e159.

[21]A.Zehe,J.G.VazquezLuna,Sol.EnergyMater.Sol.Cells68(2000)217e226.[22]J.Herreo,M.T.Gutierrez,C.Guillen,J.M.Dona,M.A.Martinez,A.M.Chaparro,

R.Bayon,ThinSolidFilms28(2000)361e362.

[23]Y.Nosaka,K.Yamaguchi,H.Miyama,H.Hayashi,Chem.Lett.87(1988)605e608.[24]M.A.Martinez,C.Guillen,J.Herrero,Appl.Surf.Sci.140(1999)182e191.[25]H.Masuda,K.Fukuda,Science268(1995)1466e1468.

[26]O.Jessensky,F.Müller,U.Gösele,Appl.Phys.Lett.72(1998)1173e1175.[27]F.Li,L.Zhang,R.M.Metzger,Chem.Mater.10(1998)2470e2480.

[28]M.Gowtham,L.Eude,C.S.Cojocaru,B.Marquardt,H.J.Jeong,P.Legagneux,

K.K.Song,D.Pribat,Nanotechnology19(2008)1e6.

[29]S.Guduru,V.P.Singh,S.Rajaputra,S.Mishra,R.Mangu,IngridSt.Omer,Thin

SolidFilms518(2010)1809e1814.

[30]O.Trujillo,R.Moss,K.D.Vuong,D.H.Lee,R.Noble,D.Finnigan,S.Orloff,

E.Tenpas,C.Park,J.Fagan,X.W.Wang,ThinSolidFilms290e291(1996)13e17.

[31]J.Lee,ThinSolidFilms451e452(2004)170e174.

[32]O.Vigil,I.Riech,M.Garcia-Rocha,O.Zelaya-Angel,J.Vac.Sci.Technol.A15

(1997)2282e2286.

[33]M.Agata,H.Kurase,S.Hayushi,K.Yamamoto,SolidStateCommun.76(1990)

1061e1065.

本文来源：https://www.bwwdw.com/article/uzxq.html