E第3章光电子发射探测器.ppt

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1、Chapter3PhotoelectricemissiondetectorPhotoelectricemissiondetector(VacuumPhotodetector)PhototubeandPhotomultipliertubeCharacteristicsandapplicationofmultiplierphototube7/28/20212§3-1PhotoelectricemissioneffectEinsteinequation7/28/202133.1.1PhotoelectricemissionofmetalEFEAT=0T>0Ene

2、rgydistributionofelectronSurfacebarrierEFermienergylevelT＝0：7/28/20214EFEAT=0T>0EnergydistributionofelectronSurfacebarrierEFermienergylevelT>0：7/28/20215Superperformance：lowreflectancemoderateconductanceofcathodealotofemissioncenterlittleescapepower3.1.2Photoelectricemissionofsemi

3、conductor7/28/20216Emissionprocessofsemiconductor1.AbsorptionofphotonIntrinsicemission:η－－20％－30％Impurityemission:η－－1％freecarrieremission:negligible7/28/202172.photoelectronmovingtosurfaceLatticescattering,collisionwithvalenceelectronAbsorptioncoefficientEg7/28/202183.Againstsurf

4、acepotentialenergytoescape7/28/20219Classifyofphotoelectricemissionmaterial：PuremetalmaterialAdulteratedmetalorsemiconductorPhotoelectriccathodefunction：§3-2Materialofphotoelectricemission7/28/2021103.2.1PrincipalParametersofPhotoelectricCathode1.Luminoussensitivity（luminoussensiv

5、ity／chromalightsensitivity／spectrumsensitivity）（1）Luminoussensitivity:μA/lm。7/28/202111(2)Chromalightsensitivity(blue:QB24,red:HB11,infrared:HWB3)wavelength/nmtransmissivity/%7/28/202112(3)Spectrumsensitivity:mA/WorA／W7/28/2021132．Quantumefficiency7/28/2021143．Spectrumresponsecurv

6、eS----λQ----λ4．Thermoelectronemission10－16～10－17Acm－27/28/2021153.2.2NormalPhotoelectricEmissionMaterialConditions(1)Lightabsorptioncoefficient(2)Transmissionenergyloss(3)Surface-potentialbarriermetalsemiconductor7/28/2021161.Ag-O-CsphotocathodewwwwwwCsatominternalabsorptionatom7/

7、28/2021172．SinglealkaliantimonidephotocathodeAlkalimetals－Sb，Pbplumbum,Bi,Ti7/28/2021183．Muti-alkaliantimonidephotocathode4．Violetphotocathode“Solarblind”photocathodeCeTe(0.32μm)andCeI(0.2μm)7/28/2021193.2.2Negativeelectronaffinity(NEA)MaterialPositiveelectronaffinity(PEA)photocat

8、hodeNegativeelectronaffinity(NEA)