半导体课后答案

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1、一1.Whatissemiconductor?Listtwoelementalsemiconductormaterialsandtwocompoundsemiconductormaterials2.WhatiscalledCrystal?3.WhatisUnitCell?WhatisPrimitiveCell?Whatisthedifferencebetweenthem?4.Thelatticeconstantofaface-centered-cubicstructureis4.75A.Determinethevolumedensityofatoms.Answe

2、r：1.Semiconductorsareagroupofmaterialshavingconductivitiesbetweenthoseofmetalandinsultoars,typicallyp=10-4^10-7Qm.TwocommonelementalsemiconductormaterialsareSiliconandGermanium.TwocommoncompoundsemiconductormaterialsareGalliumphosphide(GaP)andGalliumarsenide(GaAs)2.Single-crystalmate

3、rials,ideally,haveahighdegreeoforder,orregulargeometricperiodicity,throughouttheentirevolumeofthematerial.3.Aunitcellisasmallvolumeofthecrystalthatcanbeusedtoreproducetheentirecrystal.Aunitcellisnotauniqueentity.Aprimitivecellisthesmallestunitcellthatcanberepeatedtoformthelattice.4De

4、nsity=4atoms/(4.75x10"8)Thestructureoftheunitcellforamineralcalledperovskiteisshownbelow.Assumingthecubiclatticewitha=6°A,whatarethevolumedensitiesofTi,Ca,andOatoms?=8.421x1023atomspercm3二1.Sketchthreelatticestructures:(a)simplecubic,(h)body-centeredcubic,and(c)foce-centeredcubic.2.F

5、orasimplecubiclattice,determinetheMillerindicesfortheplanesshowninFigure1.Ca(calcium)O(oxigcn)JTi(titanium)3.Whatismeantbyasubstitutionalimpurityinacrystal?Whatismeantbyanintcrstilialimpurity?2.left:(313);right:(121)3.solution:Density(Ca)=x8atoms/a3=4.63x1021atomspercm3Density(O)=6xg

6、atoms/a3=1.39x1022atomspercm3Density(Ti)=l/a‘=4.63xIO21atomspercm3一1.Ultravioletlight(紫夕卜光)ofwavelength150nmfallsonachromium[/kroomi:om](钮Cr)electrode(电极).Calculatethemaximumkineticenergyandthecorrespondingvelocityofthephotoelectrons(theworkfunctionofchromiumis4.37eV).2.Calculatethep

7、hotonenergiesforthefollowingtypesofelectromagneticradiation:(a)a600kHzradiowave;(b)the500nm(wavelengthof)greenlight;(c)a0.1nm(wavelengthof)X-rays.1.241xlO^eV-m150xl0_9m1>Solution:usingtheequationofthephotoelectriceffect,itisconvenienttoexpresstheenergyinelectronvolts.Thephotonenergyi

8、s=8.27^Vhv=A