載子壽命原理測(cè)試方法的實(shí)際作用

Page1FromGeneration產(chǎn)生/Recombination重組Mobility移動(dòng)率/DiffusionLength擴(kuò)散長(zhǎng)度,

CarrierLifetime載子壽命/Implied-Voltage暗電壓,QSS-Photoconductance/QSS光電導(dǎo)AndPhotoLuminescence/PL光激發(fā)Rs,ELImagingTechnologies成像技術(shù)ToFinishedCellEfficiency效率Page2P型及N型半導(dǎo)體形成P-N結(jié),(Junction)由于摻雜(Doping)濃度變化會(huì)使電子,電洞進(jìn)行梯度擴(kuò)散。進(jìn)一步打破原有電中性，形成空間電荷區(qū)（SpaceChargeRegion）及內(nèi)建電場(chǎng)（由N型指向P型）。

當(dāng)入射光子在空乏區(qū)產(chǎn)生電子-電洞時(shí)，加上內(nèi)建電場(chǎng)使電子-電洞漂移（Drift）形成由N型流向P型的光電流（Photo-Current）,當(dāng)然必須在復(fù)合（Recombination）之前，有效地經(jīng)由電極流至負(fù)載。值得注意：此光電流對(duì)P-N接面而言，是反向電壓的電流方向.

入射光不僅在空乏區(qū)產(chǎn)生電子-電洞對(duì)，電中性區(qū)（Quasi-Neutral）,也就是N型及P型也能產(chǎn)生電子-電洞對(duì)，以擴(kuò)散(Diffusion)電流形式貢獻(xiàn)光電流。這部分是由少數(shù)載子形成的擴(kuò)散電流（多數(shù)載子固定在晶格中）。

光電流輸出：IDiffusion+IDrift

一般所采用的模型-IRL=IL-IS（eV/VT-1）光電流與載子Page3動(dòng)態(tài)偏壓情況下的PN結(jié)中性區(qū)／空乏區(qū)在以太陽(yáng)模擬測(cè)試系統(tǒng)量測(cè)太陽(yáng)電池片IV曲線時(shí)，PN結(jié)存在一個(gè)動(dòng)態(tài)偏壓情況下工作。為解決此復(fù)雜現(xiàn)象，單一二極體模型須要增加另一代表合復(fù)電流的二極管（及串，并聯(lián)電阻）才足夠充分說(shuō)明空乏區(qū)復(fù)合現(xiàn)象及太陽(yáng)電池等效電路

Page4A.初步描述空乏區(qū)電場(chǎng)

(漂移電流-DriftCurrent)B.進(jìn)一步描述類(lèi)中性區(qū)摻雜濃度梯度（擴(kuò)散電流

-DiffusionCurrent)C.強(qiáng)調(diào)載子由于激發(fā)所產(chǎn)生與復(fù)合而形成電流梯度

復(fù)合與過(guò)剩載子基本關(guān)系各種復(fù)合機(jī)制少子壽命的倒數(shù)0?V?V0?V/et?

n(?p)=Ae-t/

,

islifetime,?p,?nisexcesscarriersPhotovoltagefollowthelaw:?V=?V0e-t/Page6τeff==Δnqw

Jph移動(dòng)率(Mobility)與電導(dǎo)σL

–由光產(chǎn)生過(guò)剩載子濃度增加，導(dǎo)致WaferConductivity增加–Jphotogeneration=JrecombinationσLJph(μn+μp)

-依Wafer表面反射，厚度，光照條件及LightTrapping情形而調(diào)整Excesscarrierdensityispositiondependentandconsideringthickness,asaveragevalueMobilitiesareafunctionthemselvesofcarrierdensity(bothviadopingandexcitation)andtemperature

Therefore,theabsolutevalueofconductanceahouldbealwaysmeasuredinordertodeterminethespecificexcesscarrierdensityatwhichthemeasurementhastakenplacedCuevas,Macdonald2003ANU體壽命τb與有效壽命τeffPage7體壽命τb與有效壽命τeffPage8體壽命τb與有效壽命τeffPage9Page10

Db是材料的擴(kuò)散系數(shù)，τb是材料的體壽命在測(cè)試的少子壽命中，實(shí)際上是不同復(fù)合機(jī)制的綜合結(jié)果，實(shí)際上是整個(gè)樣品的有效壽命

WithNon-DiffusedSurface其中，Sfront,Sback分別為Si片前後表面的復(fù)合速度W為Si片的平均厚度τeff為有效壽命τSRH是少子復(fù)合壽命體壽命τb與有效壽命τeff●bbbDLt=Page11–BandtoBand，由於RadiativeLifetime很長(zhǎng)對(duì)於Si材料影響不大，可以不計(jì)入考慮.(對(duì)直接能隙GaAs較明顯)–Auger與雜質(zhì)濃度無(wú)關(guān)，但與載子濃度平方成反比–SRH直接與Si材料雜質(zhì)有關(guān)，所以當(dāng)載子濃度高時(shí)，Auger復(fù)合為主要因素，而低載子濃度時(shí)，由SRH復(fù)合為主電子電洞產(chǎn)生Generation與合復(fù)Recombination(一)Page12

NA是片子的摻雜濃度

是在前後表面擴(kuò)散區(qū)域的飽和電流密度ni是材料的本征載流子濃度Δn

是在某個(gè)光照強(qiáng)度下的過(guò)剩載流子濃度電子電洞產(chǎn)生Generation與合復(fù)Recombination(二)WithDiffusedSurface●●●●●Page13Page14Page15Page16Page17Page18Page19Page20StandardProductionCell:1x10E13—5X10E14,atVocHighEfficiencyCell:1x10E151X10E16ConcentrationPV:1X10E17ThinCrystallineSiliconSolarCell:1x10E13Page21WCT-120:SiliconWaferLifetimeTesterwithSuns-VocPage22Page23Page24測(cè)試載子壽命三個(gè)基本方法（1）瞬態(tài)光電導(dǎo)衰減（TPCD）（2）穩(wěn)態(tài)光電導(dǎo)衰減（SSPCD）（3）準(zhǔn)穩(wěn)態(tài)光電導(dǎo)（QSSPC）Page25TPCDQSSPCPage26Page27GoodAgreementbetweenQSS-PCandMW-PCD,butthiswashistory!!NowweneedtounderstandtheresultinamoreaccuratewayPage28Page29QSS-PLandQSS-PCAi:ProportionalconstantBi:RadiativerecombinationcoefficientBTImagingBTImagingPage30Page31CapabilityandRestrictionwithlongtermviewPage32TI-PL–TemperatureandInjectionDependentPhotoLuminescenceDLTS–DeepLevelTransientSpectroscopyTDLS–TemperatureDependent(LowInjection)lifetimespectroscopyIDLS–InjectionDependentlifetimespectroscopyI-LIT/CDI–IlluminatedLock-In-Thermography,CarrierDensityImageFutureconcernsaboutCarrierLifetimePage33MultiToolI-LIT,CDI,SRIILITILITIlluminatedLock-InThermographyI-LITforPowerLossImageLifetimeImageSheetResistanceImagineFastI-LITatOneSecondforProductionIn-LineMonitoringPage34ElectroluminescenceforCharacterisationofSolarCellsFigure2:Visualimageofasolarcellinalaminatedmodule.Figure3:Electroluminescenceimageofthesamesolarcell.Page35SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage36SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage37SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage38SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage39SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage40SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage41SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage42SPATIALLYRESOLVEDSILICONSOLARCELLCHARACTERIZATIONUSINGINFRAREDIMAGINGMETHODSPage43COMPARINGLUMINESCENCEIMAGINGWITHILLUMINATEDLOCK-INTHERMOGRAPHYANDCARRIERDENSITYIMAGINGFORINLINEINSPECTIONOFSILICONSOLARCELLSPage44COMPARINGLUMINESCENCEIMAGINGWITHILLUMINATEDLOCK-INTHERMOGRAPHYANDCARRIERDENSITYIMAGINGFORINLINEINSPECTIONOFSILICONSOLARCELLSPage45COMPARINGLUMINESCENCEIMAGINGWITHILLUMINATEDLOCK-INTHERMOGRAPHYANDCARRIERDENSITYIMAGINGFORINLINEINSPECTIONOFSILICONSOLARCELLSPage46COMPARINGLUMINESCENCEIMAGINGWITHILLUMINATEDLOCK-INTHERMOGRAPHYANDCARRIERDENSITYIMAGINGFORINLINEINSPECTIONOFSILICONSOLARCELLSPage47PHOTOLUMINESCENCEIMAGINGONSILICONBRICKSPage48PHOTOLUMINESCENCEIMAGINGONSILICONBRICKSPage49PHOTOLUMINESCENCE