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RETRACTEDORIGINALOpenAccessRetracted:Structural,electrical,andopticalpropertiesofATOthinfilmsfabricatedbydipcoatingmethodTalaatMHammad1*andNaserKHejazy2RetractionThisarticlewasmistakenlypublishedtwice.
Forthisreasonthisduplicatearticlehasnowbeenretracted.
Forcitationpurposespleasecitetheoriginal:http://www.
inljournal.
com/_action=articleInfo&article=22AbstractAntimony-dopedtinoxide(ATO)thinfilmswerepreparedbydipcoatingmethod.
Theeffectofantimonydopingonthestructural,electrical,andopticalpropertiesoftinoxidethinfilmswereinvestigated.
Tin(II)chloridedehydrate(SnCl2·4H2O)andantimony(III)chloride(SbCl3)wereusedasahostandadopantprecursor,respectively.
X-raydiffractionanalysisshowedthatthenon-dopedSnO2thinfilmhadapreferred(211)orientation,butastheSbdopingconcentrationincreased,apreferred(200)orientationwasobserved.
Thelowestresistivity(about5.
4*103Ωcm)wasobtainedforSb-dopedfilmsat2at.
%.
AntimonydopingledtoanincreaseinthecarrierconcentrationandadecreaseinHallmobility.
ThetransmittanceofATOfilmswasobservedtoincreaseto96%at2at.
%Sbdoping,andthen,itwasdecreasedforahigherlevelofantimonydoping.
Keywords:Electricalproperties,Opticalproperties,ATO,Thinfilms,DipcoatingBackgroundTransparentconductingoxide(TCO)filmsarewidelyusedinavarietyofoptoelectronicdevicessuchassolarcells,displays,andelectrochromicdevices.
Inrecentyears,therehasbeenagrowinginterestintheapplica-tionofTCOfilmsaselectrodesinsolarcelldevices.
AmongtheTCOfilms,themostappropriatematerialfortheapplicationseemstobetinoxidefilms,whicharechemicallyinert,mechanicallyhard,andheatresistant.
Inaddition,theyexhibitlowelectricalresistivityandhighopticaltransmittance.
Eitherdopedornon-doped,tinoxidethinfilmscanbefabricatedbyanumberoftechni-ques:chemicalvapordeposition[1],sputtering[2],sol-gelcoating[3],andspraypyrolysis[4-6].
Thesol-gelmethodhassuchadvantagesascheapcostandflexibledepositiontechnique.
Suchpropertiescanbeimprovedbydopingtinoxidewith,forexample,antimony(Sb),indium(In),orfluorine(F).
Infact,byincreasingthedopingconcentration(>2%),adegeneratesemiconductorisformed,displayinghigherσvalues(>103Ω1cm1).
Sincethisdopinglevelisnottoohigh,dopedSnO2thinfilmsaretransparentforvisiblelight,whichmakesthemusefulforadeviceapplicationpointofview.
Also,thenature,quantity,andstructuraldistributionofdopingareimportantfactorsfortheelectricalpropertiesofSnO2[7].
ThecurrentstudyinvestigatesthecharacteristicsofSb-dopedSnO2thinfilmspreparedbydipcoatingtech-nique.
Thestructural,electrical,andopticalpropertiesofthethinfilmsareexaminedinrelationtotheincreaseintheantimonyamount.
MethodsTheantimony-dopedtindioxidesolswerepreparedusingthesamemethodologyutilizedinourpreviousliterature[8].
TheSnO2solutionwasobtainedbydissolving2.
01gofSnCl4·4H2Oin25mlofabsoluteethanol.
ToachieveSbdoping,antimonytrichloride(SbCl3)wasaddedtotheprecursorsolution.
TheamountofSbCl3tobeaddeddependsonthedesireddopingconcentration.
Thedopingconcentrationvariedfrom0to7at.
%.
Thesolutionwas*Correspondence:talaath55@yahoo.
com1PhysicsDepartment,FacultyofScience,Al-AzharUniversity,P.
O.
Box1277,GazaStrip,Gaza,00970,PalestineFulllistofauthorinformationisavailableattheendofthearticle2012HammadandHejazy;licenseeSpringer.
ThisisanOpenAccessarticledistributedunderthetermsoftheCreativeCommonsAttributionLicense(http://creativecommons.
org/licenses/by/2.
0),whichpermitsunrestricteduse,distribution,andreproductioninanymedium,providedtheoriginalworkisproperlycited.
HammadandHejazyInternationalNanoLetters2012,2:7http://www.
inl-journal.
com/content/2/1/7RETRACTEDstirredat70°Cfor6hinaclosedcontainerforthehomogenousmixingofthesolutionandthenwasagedintheairfor24h,i.
e.
,untilthesolidmaterialsdissolved.
Thethinfilmsweredepositedbydipcoatingtechniqueonglasssubstrates,whichhadbeencleanedultrasonicallyinacetone,rinsedinDIwater,andthendriedbyN2blowing.
Thecleanglasssubstratesweredippedverticallyandcare-fullyintothesol,leftforashorttime,andwithdrawnfromthebathatwithdrawalspeedsintherangeof1to10mm/s.
Thiswasfollowedbydryingandthensin-teringofthefilmsbetween400°Cand550°Cforperiodsrangingfrom6to24h.
Toobtainhigherthicknessfilms,thesequenceofdipping,drying,andthendippingagainwasperformedanumberoftimes.
However,sin-teringwasdoneonlyafterthefinaldipping.
Thethick-nessofthefilmsincreasedalmostlinearlywiththenumberoftimesofdipping.
Thefilmswerekeptat25°Candhumidityof40%RH.
Allmeasurementswereper-formedinthesameconditionsandafterthefinalanneal-ing.
Thefilmthickness,t,wasmeasuredwithaTencorP10profilometer,(KLA-TencorCorporation,Milpitas,CA,USA).
Themeasurementaccuracyofthisequipmentforthethicknessmeasurementis0.
1nm.
Thesheetresist-ance,R,ofthefilmswasmeasuredbythelinearfour-pointmethod.
Theelectricalresistivity,ρ,wasdeterminedbytherelationρ=Rt.
TheopticaltransmittanceofthefilmswasmeasuredusingaUV-visiblespectro-photometer(Cary500,AgilentTechnologies,Inc.
,SantaClara,CA,USA).
Crystalstructureidentifica-tionandcrystalsizeanalysiswerecarriedoutbyX-raydiffraction(XRD)(2000,SCintagInc.
,Cupertino,CA,USA)withaCu-Kαradiationsourceandascanrateof2°/min.
ResultsanddiscussionFigure1showstheXRDpatternsofthesol-gelATOthinfilmswitha220-nmthicknessdepositedat550°CasafunctionofSbdopingconcentration.
ThepreferredorientationchangedwithSbdoping.
Thenon-dopedSnO2thinfilmshadapreferred(211)orientation.
How-ever,astheSbdopingamountincreased,theintensityofthe(211)peakdecreasedandthe(200)peakintensityincreased.
Thus,thepreferred(200)orientationwasobservedforSb-dopedfilmsat2to7at.
%.
Thepreferred(200)orienta-tionwasalsoreportedbyElangovanetal.
[6].
Thisbehav-iorwithSbdopingimpliesthatinthepresentcase,antimonyincorporationinSnO2latticehasnotaffectedthestructuralpropertiestoaconsiderableextent.
Ontheotherhand,forhigherdopantlevels,theincorporationwouldtakeplaceatinterstitialsites,andsomeprecipita-tionlikeantimonyoxides(Sb2O3,Sb2O4,andSb2O5)couldbeinduced[9].
Asaresult,withtheincreaseofdop-ingconcentration,thedepositedfilmslosethecrystallin-ity,andthepreferredorientationgrowthofSnO2filmsmaybesuppressedbytheprecipitation.
Inthepresentcase,antimonyincorporationinSnO2latticehasnotaffectedthestructuralpropertiestoaconsiderableextent.
ItisalsoclearthatinFigure1,thecrystallinityimprovesinitiallywithantimonydopingupto7at.
%inthepresentcase,butitdecreasesprogressivelybeyond7at%dopingconcentration,asobservedbyShanthietal.
[10].
TheeffectofdopingontheelectricalpropertiesofATOthinfilmshasbeeninvestigated.
Figure2showsthevariationoftheresistivity(ρ)withdifferentSbdopingconcentration(atomicpercentage).
TheresistivityofATOthinfilmsdecreasesinitiallywithanincreaseintheSbFigure1XRDpatternsofsol-gelATOthinfilmsdepositedat550°CasfunctionofSbdopingconcentration.
Figure2ResistivityofATOthinfilmswithSbdopingconcentration.
HammadandHejazyInternationalNanoLetters2012,2:7Page2of5http://www.
inl-journal.
com/content/2/1/7RETRACTEDdopingconcentrationtoabout4*104Ωcmfor2at.
%ofSbbutincreasesagainforfurtherdoping.
TheobservedminimumissignificantlylessthanthatforpureSnO2thinfilms(5.
4*103Ωcm).
ThedecreaseinresistivitywhichmaybeattributedtothesubstitutionofSn4+bySb5+[10],astheirionicradiimatch(Sn4+0.
071nmandSb5+0.
065nm).
ThevariationintheresistivityoftinoxidethinfilmswithantimonydopingisexplainedonthebasisofthepresenceofSbintwooxidationsstates,namelySb5+andSb3+.
Thepossiblemechanismmaybeasfollows.
WhenSnO2isdopedwithSb,apartofthelatticeSn4+atomsarereplacedbySb5+,resultinginthegenerationofconductionelectronsandthusthedecreaseofresistivity[11,12].
Hence,acontinuousdecreaseofresistivityisobserveduntilSbdopingconcentration≤2at.
%.
Beyond2at.
%ofSb,theresistivityincreasesagain(Figure2).
Thisisbecausebeyond2at.
%ofSbdoping,apartofSb5+ionsreducestotheSb3+state,resultingintheformationofacceptorsitesandconcomitantlosscarriers[13-16].
ThereductionofSb5+toSb3+hasbeenverifiedbyTerrieretal.
[12]byesti-mationofthelatticeparameterofthedopedSnO2films.
SincetheionicradiusofSn4+islessthanthatofSn3+buthigherthanthatofSn5+,anincreaseinthelatticeparam-eterofSnO2phaseisobservedbeyond2at.
%ofSbdop-ing.
ThisreductionofSb5+toSb3+canbeattributedtotheincreaseintheresistivityaboveanoptimumlevelofSbdoping.
Itisobservedthatthissubstitutionincreasesthecar-rierconcentrationandtherebydecreasesresistivity.
Thus,wecouldobtainthethinfilmswhichhavethelow-estresistivityat2at.
%Sbdopinglevel.
TheresistivityρisproportionaltothereciprocaloftheproductofcarrierconcentrationnandHallmobilityμ,asinthefollowingequation:ρ1neμ:1AsshowninFigure3,Hallmobilitydecreasedfrom0.
9024to0.
2901cm2/VswithSbdoping.
TheincreaseinHallmobilitymaybeattributedtothe(1)increaseintheadditionofantimonyatthetinsiteand(2)adecreaseingrainboundaryscattering.
Itisknownthatgrainbound-aryscatteringandionizedimpurityscatteringaretwomajorscatteringmechanismsdeterminingthemobilityFigure3HallmobilityofATOthinfilmsasafunctionofSbdopingconcentration.
Figure4VariationofcarrierconcentrationwithatomicpercentageofSbdopingforATOthinfilms.
Figure5OpticaltransmissionsofundopedSnO2andseveralSb-dopedSnO2thinfilmsasawavelengthfunction.
HammadandHejazyInternationalNanoLetters2012,2:7Page3of5http://www.
inl-journal.
com/content/2/1/7RETRACTEDvariationofsuchextrinsicdopedsemiconductors.
Theresultantmobilityisgivenasfollows:1=μ1=μgb1=μis;2whereμistheresultantmobility;μgbisthemobilityduetograinboundaryscattering;andμisisthemobilityduetoionizedimpurityscattering.
TheseobservationsareinclosecoincidencewiththoseofShanthi[10],Agashe[17],andAdvani[18].
Figure4showsthecarriercon-centrationofthinfilmswithanincreaseinSbdopingconcentration.
ThesubstitutionofSn4+bySn5+ledtoanincreaseinthecarrierconcentrationbecausetheradiiofthetwoionsmatched.
ThecarrierconcentrationofSnO2thinfilmswas2.
004*1019cm3andthevalueincreasedcontinuouslywithSbdopingto6*1019cm3at8at.
%Sbdopingconcentration.
TheeffectofdopingontheopticalpropertiesofATOthinfilmshasbeeninvestigated.
Figure5showsthetransmittancespectraofATOthinfilmswithathicknessof220nmintherangeof300to2,000nm.
Maximumtransmittanceisfoundtobe96%(at502nm)fortheATOfilmdopedwith2at.
%ofSb,whichisattributedtothelowscatteringeffectandthicknessuniformityofthefilmduetosurfacesmoothnessofthefilm.
However,thetransmittanceisfoundtode-creasegraduallyiftheantimonyconcentrationisincreasedabove2at.
%.
Thedecreaseintransmittancewiththein-creaseindopantconcentrationmaybeattributedtothein-creaseinclustersizeandsurfaceroughnessofthefilm,whichpromotesthediffuseandmultiplereflectionsatthesurfaceandincreasestheabsorption.
TheseobservationsarewellinagreementwiththeresultsillustratedbyAdvanietal.
andManifacier[18,19],Jarzebski[20],Ambrazevi-ciene[21],andShanthi[22].
Inthecaseofheavilydopedsemiconductorswithcarrierconcentrationbeingapproxi-mately1019to1021cm3,theDrudemodelcanbegener-allyusedtorepresentthedecreaseinthetransmittance[23-25].
Briefly,themodelindicatesthatthetransmittancedropinthenearinfraredregionisassociatedwiththeplasmafrequency(ωp)thatcanbeexpressedasfollows:ωpne2εoε∞m1=2;3wherenisthecarrierconcentration;e,theelectroniccharge;ε0,thepermittivityoffreespace;ε∞,thehigh-fre-quencypermittivity;m*,theconductivityeffectivemass.
Belowtheplasmafrequency,thefilmsarecharacterizedbyahighreflectance,whichfunctionsasascreenoftheinci-dentelectromagneticwave[25].
Asωpisproportionaltothesquarerootofthecarrierconcentration,theincreaseinthecarrierconcentrationledtotheloweringofthetrans-mittancelevelneartheinfraredregion.
ConclusionsTransparentconductingATOthinfilmswerepreparedbydipcoatingmethodviasol-gelroute.
Apreferred(211)orientationwasobservedforthenon-dopedSnO2thinfilms,butastheSbdopingconcentrationincreased,apreferred(200)orientationappearedforSb-dopedfilmsat3to7at.
%.
WiththeincreaseintheSbdopingconcentration,thepolyhedron-likegrainsbecamerounderandsmaller.
ThecarrierconcentrationofSnO2thinfilmswas2.
004*1019cm3,andthevalueincreasedcontinuouslywithSbdopingto6*1019cm3at8at.
%Sbdopingconcentration,whiletheHallmobilitydecreasedfrom0.
9024to0.
2901cm2/Vs.
Theresistivitydecreasedto2at.
%Sbdopingconcentration;thereafter,itincreased.
Thus,thelowestresistivity(about5.
4*103Ωcm)wasobtainedfortheSb-dopedfilmsat2at.
%.
ThemosteffectivetransparentconductingATOthinfilmwastheSb-dopedfilmsat2at.
%.
CompetinginterestsTheauthorsdeclarethattheyhavenocompetinginterests.
Authors'contributionsNKHmadetheexperimentonthethinfilmsandperformedtestsonthesamples.
TMHcarriedoutthecharacterizationandwrotethemanuscript.
TMHgavethefinalapprovaloftheversiontobepublished.
Alltheauthorsreadandapprovedthefinalmanuscript.
Authors'informationTMHisaprofessorofMaterialScienceinthePhysicsDepartment,FacultyofScienceinAl-AzharUniversity,Gaza,Palestine.
HegothisPh.
D.
(May1998)inSolidStatePhysicsfromMoscowStateUniversity.
Hisresearchinterestsincludesolidstatephysics,thinfilmcoating,materialscience,andnanotechnology(nanoparticles,nanowires,nanorods).
NKHisanassistantprofessorofPhysicalChemistryintheChemistryDepartmentinAl-QudsOpenUniversity,Gaza,Palestine.
HegothisPh.
D.
(February2009)inPhysicalChemistryfromAinShamesUniversity,Cairo,Egypt.
Hismainresearchareasarethinfilmcoatingandnanostructureandtheircharacterizations.
AcknowledgmentsTheauthorswouldliketogratefullyappreciatethefinancialsupportfromtheDAADandSaarlandUniversity,Germany.
Wealsoacknowledgetheeditorwhomadethesignificantrevisionandcontributiontowardsourarticle.
Authordetails1PhysicsDepartment,FacultyofScience,Al-AzharUniversity,P.
O.
Box1277,GazaStrip,Gaza,00970,Palestine.
2DepartmentofEducation,Al-QudsOpenUniversity,GazaBranch,GazaStrip,Gaza,00970,Palestine.
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