电子技术专业英语教学课件作者何茗unit5.ppt

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1、Unit5SemiconductorMaterialsIntroductionSolidstatematerialscanbegroupedintothreeclasses—insulators,semiconductors,andconductors.Table1.5.1showstheelectricalconductivitiesσ(andthecorrespondingresistivitiesρ=1/σ)associatedwithsomeimportantmaterialsineachofthethreeclasses.Insulatorssuchassilic

2、ondioxide(SiO2)andglass(SiON)haveverylowconductivities,intheorderof10-18to108S·cm-1;andconductorssuchasaluminum(Al)andsilver(Ag)havehighconductivities,typicallyfrom102S·cm-1to108S·cm-1.下一页返回Unit5SemiconductorMaterialsSemiconductorshaveconductivitiesbetweenthoseofinsulatorsandthoseofcondu

3、ctors.Theconductivitiesofasemiconductorisgenerallysensitivetotemperature,illumination,magneticfield,andminuteamountofimpurityatoms.Thissensitivityinconductivitymakesthesemiconductorsoneofthemostimportantmaterialsforelectronicsapplications.Silicon(Si),germanium(Ge),galliumarsenide(GaAs)andi

4、ndiumphosphide(InP)arethemostpopularmaterialsinsemiconductormaterials.Thestudyofthesesemiconductormaterialswillbedescribedindetail.下一页上一页返回Unit5SemiconductorMaterialsSilicon(Si)Silicon(Si)isthesecondmostabundantmaterialintheearth’scrust(25.7wt%)afteroxygen(46.7%).Siliconisanindirectgapsemi

5、conductor.Siisthemostimportantofthesemiconductors,totallydominatingthepresentcommercialmarket,dueinlargeparttotheadvancedstateofitsfabricationtechnology.SiphysicalpropertiesareshowninTable1.5.2.Itisthesubstancemostwidelyusedastheactiveelementofamajorityofmodernelectronicdevicesutilizingit

6、selectrical,optical,photoelectrical,thermoelectrical,thermal,mechanical,andotherproperties.下一页上一页返回Unit5SemiconductorMaterialsTheopticalindirectenergygapofsiliconat300Kof1.124,2eV(1.170,0eVat0K),togetherwiththeoutstandingelectricalandopticalpropertiesofSiO2,makessiliconveryattractive,incr

7、ystalline,thinfilms,andamorphousforms,forapplicationinrectifiers,thyristors,solarenergyconverters,fieldeffecttransistors(FET),etc.下一页上一页返回Unit5SemiconductorMaterialsGermanium(Ge)Germanium(Ge)isanindirectgapsemiconductor.Itisoneofthemoststudiedsubstancesaftersi