Materials-Letters样稿

ThegrowthandtheultravioletphotoresponsepropertiesofthehorizontalgrowthZnOnanorodsLiangGuo,HongZhang,DongxuZhao,BinYao,BinghuiLi,Zhen-zhongZhang,DezhenShenPII:S0167-577X(11)00167-4DOI:doi:10.1016/j.matlet.2011.02.051Reference:MLBLUE11966Toappearin:MaterialsLettersReceiveddate:16December2010Accepteddate:17February2011Pleasecitethisarticleas:GuoLiang,ZhangHong,ZhaoDongxu,YaoBin,LiBinghui,ZhangZhenzhong,ShenDezhen,Thegrowthandtheultravioletphotore-sponsepropertiesofthehorizontalgrowthZnOnanorods,MaterialsLetters(2011),doi:10.1016/j.matlet.2011.02.051ThisisaPDFfileofanuneditedmanuscriptthathasbeenacceptedforpublication.Asaservicetoourcustomersweareprovidingthisearlyversionofthemanuscript.Themanuscriptwillundergocopyediting,typesetting,andreviewoftheresultingproofbeforeitispublishedinitsfinalform.Pleasenotethatduringtheproductionprocesserrorsmaybediscoveredwhichcouldaffectthecontent,andalllegaldisclaimersthatapplytothejournalpertain.ACCEPTEDMANUSCRIPTACCEPTEDMANUSCRIPT1ThegrowthandtheultravioletphotoresponsepropertiesofthehorizontalgrowthZnOnanorodsLiangGuo1,2,HongZhang1,3,DongxuZhao1*,BinYao1,BinghuiLi1,ZhenzhongZhang1,DezhenShen11.KeyLaboratoryofExcitedStateProcesses,ChangchunInstituteofOptics,FineMechanicsandPhysics,ChineseAcademyofSciences,Changchun130033,People’sRepublicofChina2.GraduateSchooloftheChineseAcademyofSciences,Beijing100049,People’sRepublicofChina3.DepartmentofPhysiology,NormanBethuneCollegeofMedicalSciences,JilinUniversity,Changchun130012,People’sRepublicofChinaAbstract:ThehorizontalZnOnanorods(NRs)weregrownbyusingalowtemperaturehydrothermalmethodbetweenthelithographicZnOinterdigitalelectrodes.InordertohorizontallygrowtheZnOnanorods,theverticalgrowthwasrestrainedbycoatingwiththephotoresistonthesurfacenucleationsites.Bycontrollingthedistancebetweentheelectrodes,onlytheelectrodesforanintervalof7μmcanbeconnectedbythehorizontalnanorodstoformdevice.Theelectricalpropertyofthedevicewasmeasured.Thedetectorshowedanarrowultravioletphotoresponsewitharesponsepeakat379nm,whichwasaccordingwiththepeakofthephotoluminescence.Themechanismofphotoresponsewasdiscussed.Keywords:Crystalgrowth;Nanocrystallinematerials;Horizontalgrowth;Zincoxidenanorods;UVdetector*Correspondingauthor:D.X.Zhao,Tel:[phone],Fax:[phone]E-mailaddress:[e-mail],thedesignandthefabricationofnanomaterialsandnanodeviceshavebecomeoneofthemostactiveresearchfieldsduetotheiruniquepropertiesandpotentialapplications[1,2,3].Amongthevariousnanomaterials,zincoxide(ZnO)isaremarkableoneowingtoitsspecialproperties,suchasthewidebandgapof3.37eV,highexcitonbindingenergyanditshighthermalandmechanicalstabilities[4].Thevarious-shapedZnOnanostructures,includingnanobelts,nanowiresandnanorings[5,6]havebeenstudiedforultraviolet(UV)optoelectronicapplication.Variousnanodevicesbasedononedimensional(1D)ZnOnanostructureshaveexhibitedspecialproperties,suchaslaserdiodes[7],lightemittingdiodes(LED)[8,9],ultravioletdetector[10,11,12],gassensors[13,14]etc..However,thefabricationoftheZnONRsdevicesisstillachallenge.Therearetwomainmethodstomakenanodevicesusing1Dnanostructure.Oneistouseasinglenanowiretobuildnanodevices,inwhichsomespecialequipmentisneededtooperateinnanoscale[15,16].Theotheroneistodesignnanodevicesbasedonnanowiresarraywithsometraditionalmethods[12,17].Theessentialsforthesecondmethodarethecontrollablegrowthofnanowiresandtheproperdesignofthenanodevices.TheverticalalignedZnOnanowiresarrayisoftenusedasabuildingblocktofabricateoptoelectronicdevices[18].Inthisstudy,wetriedtogrowhorizontalZnOnanorodsbetweenthepatternedelectrodes.Thehorizontalnanorodscoulddirectlyfabricatednanodevicesonelectrodes.OurmethodcanalsoavoidtheinsulationfillingandsurfaceetchingprocessesinmakingtheverticallygrownZnOnanorodsbaseddevices.Furthermore,wealsocharacterizedtheultravioletphotoresponsepropertiesofthehorizontalnanorods.2.ExperimentalThegrowthprocessesofthehorizontalZnOnanorodsarelistedasfollow.FirstaZnOthinfilmwiththethicknessof400nmwasgrownonsapphiresubstratebyusingasputteringmethod.ThenaBP212-37positivephotoresistwasspin-coatedontheZnOfilms.Aftertheexposalandremovingsteps,theuncoveredZnOthinfilmwasetchedbythedilutedHCl(0.001mol/L)toformtheZnOinterdigitalelectrodes.TheZnOnanorodsweregrownviaahydrothermalACCEPTEDMANUSCRIPTACCEPTEDMANUSCRIPT3method.Inthisstep,thesolutioncontained0.01mol/LZn(CH3COO)2·2H2Oand0.01mol/Lhexamethylenetetramine(HMTA)whichweredissolvedindeionizedwaterservedasthesourcematerial[19].Thereactionwasmaintainedat90for12hoursinaTeflon-linedstainlessautoclave.Afterthegrowththephotoresistwasremovedbyacetone.Themorphologiesoftheproductswereobservedbyfieldemissionscanningelectronmicroscopy(FESEM,HitachiS-4800)andhighresolutiontransmissionelectronmicroscopy(HRTEM).Photoluminescence(PL)spectraweremeasuredbyusingthe325nmlineofaHe–Cdlaserasanexcitationsource.ForthecharacterizationoftheUVdetectors,a150WXelampwasusedastheexcitationsource.Thespectrumresponsewasmeasuredbyalock-inamp