载子寿命原理测试方法的实际作用

Page1FromGeneration产生/Recombination重组Mobility移动率/DiffusionLength扩散长度,

CarrierLifetime载子寿命/Implied-Voltage暗电压,QSS-Photoconductance/QSS光电导AndPhotoLuminescence/PL光激发Rs,ELImagingTechnologies成像技术ToFinishedCellEfficiency效率Page2P型及N型半导体形成P-N結,(Junction)由于掺杂(Doping)浓度变化会使电子,电洞进行梯度扩散。进一步打破原有电中性，形成空间电荷区（SpaceChargeRegion）及內建电场（由N型指向P型）。

当入射光子在空乏区产生电子-电洞时，加上内建电场使电子-电洞漂移（Drift）形成由N型流向P型的光电流（Photo-Current）,当然必須在复合（Recombination）之前，有效地经由电极流至负载。值得注意：此光电流对P-N接面而言，是反向电压的电流方向.

入射光不仅在空乏区产生电子-电洞对，电中性区（Quasi-Neutral）,也就是N型及P型也能产生电子-电洞对，以扩散(Diffusion)电流形式贡献光电流。這部分是由少数载子形成的扩散电流（多数载子固定在晶格中）。

光电流输出：IDiffusion+IDrift

一般所采用的模型-IRL=IL-IS（eV/VT-1）光電流與載子Page3動態偏壓情況下的PN結中性區／空乏區在以太阳模拟测试系统量测太阳电池片IV曲线时，PN结存在一个动态偏压情况下工作。为解决此复杂现象，单一二极体模型须要增加另一代表合复电流的二极管（及串，并联电阻）才足够充分说明空乏区复合现象及太阳电池等效电路

Page4A.初步描述空乏区电场

(漂移电流-DriftCurrent)B.进一步描述类中性区掺杂浓度梯度（扩散电流

-DiffusionCurrent)C.强调载子由于激发所产生与复合而形成电流梯度

复合与过剩载子基本关系各种复合机制少子寿命的倒数0∆V∆V0∆V/et∆

n(∆p)=Ae-t/

,

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

Jph移动率(Mobility)与电导σL

–由光产生過剩载子浓度增加，导致WaferConductivity增加–Jphotogeneration=JrecombinationσLJph(μn+μp)

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

Therefore,theabsolutevalueofconductanceahouldbealwaysmeasuredinordertodeterminethespecificexcesscarrierdensityatwhichthemeasurementhastakenplacedCuevas,Macdonald2003ANU体寿命τb与有效寿命τeffPage7体寿命τb与有效寿命τeffPage8体寿命τb与有效寿命τeffPage9Page10

Db是材料的扩散系数，τb是材料的体寿命在测试的少子寿命中，实际上是不同复合机制的综合結果，实际上是整个样品的有效寿命

WithNon-DiffusedSurface其中，Sfront,Sback分别為Si片前後表面的复合速度W為Si片的平均厚度τeff為有效寿命τSRH是少子复合寿命体寿命τb与有效寿命τeff●bbbDLt=Page11–BandtoBand，由於RadiativeLifetime很長對於Si材料影響不大，可以不計入考慮.(對直接能隙GaAs較明顯)–Auger與雜質濃度無關，但與載子濃度平方成反比–SRH直接與Si材料雜質有關，所以當載子濃度高時，Auger復合為主要因素，而低載子濃度時，由SRH復合為主電子電洞產生Generation與合復Recombination(一)Page12

NA是片子的摻雜濃度

是在前後表面擴散區域的飽和電流密度ni是材料的本征載流子濃度Δn

是在某個光照强度下的過剩載流子濃度電子電洞產生Generation與合復Recombination(二)WithDiffusedSurface●●●●●Page13Page14Page15Page16Page17Page18Page19Page20StandardProductionCell:1x10E13—5X10E14,atVocHighEfficiencyCell:1x10E151X10E16ConcentrationPV:1X10E17ThinCrystallineSiliconSolarCell:1x10E13Page21WCT-120:SiliconWaferLifetimeTesterwithSuns-VocPage22Page23Page24測試載子寿命三個基本方法（1）瞬態光電導衰减（TPCD）（2）稳態光電導衰减（SSPCD）（3）準稳態光電導（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