固体光电子导论课后习题(南邮)

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1、1.2A1.6eVphotonisabsorbedbyavalencebandelectroninGaAs.IfthebandgapofGaAsis1.41eV,calculatetheenergyoftheelectronandheavyholeproducedbythephotonabsorption.Condition:Solution:ByWecanget1.4TheabsorptioncoefficientnearthebandedgesofGaAsandSiareandrespectively.W

2、hatistheminimumthicknessofasampleineachcasewhichcanabsorb90%oftheincidentlight?Condition:Solution:ByWecangetSo1.8InaGaAssampleat300K,equalconcentrationsofelectronsandholesareinjected.Ifthecarrierdensityisn=p=1017cm-3,CalculatetheelectronandholeFermilevelsus

3、ingtheBoltzmannandJoyce-Dixonapproximations.Condition:Solution:Boltzmannapproximation:Joyce-Dixonapproximation:1.12TheradiativelifetimeofGaAssampleis1.0ns.Thesamplehasadefectatthemidgapwithacapturecross-sectionof10-15cm2.Atwhatdefectconcentrationdoesthenon-

4、radiativelifetimebecomeequaltotheradiativelifetimeati)77Kandii)300K?(分电子、空穴计算)Condition:Solution:(1)ForelectronsSo(2)ForholesSo1.13Electronsareinjectedintoap-typesiliconsampleat300K.Thee-hradiativelifetimeis1μs.Thesamplealsohasmidgaptrapswithacross-sectiono

5、f10-15cm2andadensityof1016cm-3.Calculatethediffusionlengthfortheelectronsifthediffusioncoefficientis30cm2/s.Condition:Solution:ByWegetThenSo2.1ThebandgapofalloyisgivenbytheexpressionCalculatethecompositionofanalloywhichgivesacutoffwavelengthofa)b).Solution:

6、ByWeget2.2CalculatethecutoffwavelengthforaGaAsdetector.Ifthecutoffwavelengthistobedecreasedto0.7μm,howmuchAlAsmustbeaddedtoaGaAs?AssumethatthebandgapofisgivenbySolution:ByWeget2.4Anopticalpowerdensityof1W/cm2isincidentonaGaAsSample.Thephotonenergyis2.0eVand

7、thereisnoreflectionfromthesurface.Calculatetheexcesselectron-holecarrierdensitiesatthesurfaceand0.5μmfromthesurface.Thee-hrecombinationtimeis10-8s.Condition:Solution:(1)AtthesurfaceSo(2)AtfromthesurfaceSo2.5Assumethatallthephotonsinanopticalbeamproduceanele

8、ctron-holepairinaGedetector.Ifallthecarriersarecollectedcalculatetheresponsivityforphotonenergiesofa)0.7eVb)1.0eVc)2.0eV.Condition:Solution:ByWeget2.6ConsideralongSip-njunctionwithareversebiasof1Vat300