作業(yè)一答案[3分]設(shè)InP在室溫（300K）下的電子和空穴的有效質(zhì)量分別為0.077m0和0.61m0，禁帶寬度為1.35eV。計(jì)算導(dǎo)帶和價(jià)帶的有效態(tài)密度；計(jì)算本征載流子濃度；一個(gè)摻雜了濃度為1017S原子/cm3的樣品，它的平衡態(tài)空穴密度為多少？它的費(fèi)米能級(jí)相對(duì)于本征費(fèi)米能級(jí)的距離是多少？一個(gè)p-n結(jié)的摻雜濃度為Na=1017cm-3，Nd=1016cm-3。分別計(jì)算p區(qū)和n區(qū)的多數(shù)載流子和少數(shù)載流子的濃度，并計(jì)算該p-n結(jié)的擴(kuò)散勢(shì)能和耗盡區(qū)寬度。答：（a）導(dǎo)帶有效態(tài)密度：價(jià)帶有效態(tài)密度：（b）本征載流子濃度（c）平衡態(tài)空穴密度（d）p區(qū)多數(shù)載流子為空穴少數(shù)載流子n區(qū)多數(shù)載流子為電子，==少數(shù)載流子p-n結(jié)的擴(kuò)散勢(shì)能耗盡區(qū)寬度[1分]一個(gè)光源在波長(zhǎng)范圍0.4~2.0m內(nèi)發(fā)出均勻的光強(qiáng)。在光源和光頻譜分析儀之間放置一片拋光的GaAs晶片，其兩個(gè)表面都鍍有抗反射涂層。簡(jiǎn)單畫(huà)出接收到的波長(zhǎng)譜形狀。哪種光學(xué)過(guò)程是構(gòu)成該頻譜的關(guān)鍵？答：（a）（b）吸收過(guò)程。[2分]Giventheexpressionsforthethermalequilibriumcarrierconcentrationsintheconductionandvalencebands,and,DetermineanexpressionfortheFermilevelEfofanintrinsicsemiconductorandshowthatitfallsexactlyinthemiddleofthebandgaponlywhentheeffectivemassoftheelectronsmcispreciselyequaltotheeffectivemassoftheholesmv.DetermineanexpressionfortheFermilevelofadopedsemiconductorasafunctionofthedopingleveln(orp)andshowthatitbecomestheexpressiondeterminedinpart(a)whenn=ni(orp=ni).Solution：(a)Forintrinsicsemiconductor,wehaven=p.Therefore, ,. Whenmc=mv,.(b)Foradopedsemiconductor,,.Therefore,,,.When,asinpart(a).4.[3分]GaAshasanintrinsiccarrierconcentrationni=1.8x106cm-3,arecombinationlifetime=50ns,abandgapenergyEg=1.42eV,aneffectiveelectronmassmc=0.07m0,andaneffectiveholemassmv=0.5m0.AssumethatT=0K.Determinethecenterfrequency,bandwidthandpeaknetgainwithinthebandwidthforaGaAsamplifieroflengthd=200m,widthw=10m,andthicknessl=2m,when1mAofcurrentispassedthroughthedevice.Solution:,From,weobtainthecentralfrequencyThebandwidthThegainisdeterminedbyWiththeopticaljointdensityofstateandtheFermiinversionfactorAtT=0,wehaveThepeaknetgainoccursat.Therefore,wehaveForGaAs,theinternalquantumefficiency.5.[1分]AcurrentisinjectedintoanInGaAsPdiodeofbandgapenergyEg=0.91eVandrefractiveindexn=3.5suchthatthedifferenceinFermilevelsisEfc-Efv=0.96eV.Iftheresonatorisoflengthd=250mandhasnoloss,determinethemaximumnumberoflongitudi