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1、Chapter3Modeling,Characterization,andPropertiesofTransparentConductingOxidesTimothyJ.Coutts,DavidL.Young,andTimothyA.Gessert3.1IntroductionOtherauthorsinthisbookhavediscussedatlengththeapplicationsandsynthesisoftransparentconductingoxides(TCOs).Ourpurposeinthischapteristodiscus
2、ssomeelementaryaspectsofTCOproperties,whichcanbeexplainedsurprisinglywellusingtheDrudefree-electrontheory[1].Althoughthistheoryexplainstheelectricalpropertiesandfitstheopticaldatasowell,manyhavequestionedwhetheranyfundamentalunderstandingofTCOscanbegainedfromitsuse.Webelievethat
3、muchcanbelearnedaboutthepropertiesoftheconductionelectronsinsome,butnotall,TCOs.Theconductionelectronsareimportantbecausetheydominatetheopticalpropertiesofthematerialsinthevisibleandnear-infrared(NIR)wavelengths.Thefunctionalformofthefree-electrontheoryoftenaccountsformeasurabl
4、epropertiesofTCOssuchastransmittanceandreflectance,andtheirrelationshiptoextrinsicallycontrollableproperties(e.g.,carrierconcentrationandrelaxationtime)andintrinsic,uncontrollable,properties(e.g.,crystallatticeandeffectivemass,).Indifferentrangesofwavelengths,itisreasonabletoexp
5、ectthattheopticalpropertiesaredominatedbymechanismsnotinvolvingtheconductionelectrons.Nevertheless,intherangeofwavelengthsofrelevancetoapplicationsinwhichTCOsareused(e.g.,flat-paneldisplays,solarcells,heatreflectors),thefreeelectronsdominatetheelectricalandopticalproperties.Wefind
6、thatelectricalpropertiessuchaseffectivemassandrelaxationtime,whichmaybederivedfromtheopticalcharacteristics,areessentiallyidenticaltothosemeasuredusingtheelectricalcharacterizationtechniquediscussedinthesecondsectionofthischapter.Wediscussseveralstandardtechniquesusedforcharact
7、erizingTCOs,aswellasmoreadvancedapproaches.TheseenableustodeterminefundamentalpropertiesofrelevanceandweprovideexamplesofthisforseveralTCOs.Theuseofopticaltechniquesisdiscussedinthefirstpartofthischapter.Specifically,weconsidertheT.Coutts(*)NationalRenewableEnergyLaboratory,Golde
8、n,CO80401,USAD.S.Ginleyetal.(eds.),HandbookofTranspare