路灯节能控制系统的设计英文翻译

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1、无锡职业技术学院毕业设计说明书（英文翻译）Semiconductors1SemiconductorsFundamentals1.1SemiconductorsMaterialsSolid-statematerialscanbegroupedintothreeclasses—insulators,semiconductorsandconductors.Insulatorssuchasfusedquartzandglasshaveverylowconductivities.Semiconductorshaveconductivities,typicallybetweenthoseo

2、finsulatorsandthoseofconductors.Theconductivityofasemiconductorisgenerallysensitivetotemperature,illumination,magneticfield,andminuteamountofimpurityatoms.Thissensitivityinconductivitymakesthesemiconductoroneofmostimportantmaterialsforelectronicapplication.Thestudyofsemiconductormaterialsbeg

3、anintheearlynineteenthcentury.Overtheyearsmanysemiconductorshavebeeninvestigated.Theelementsemiconductors,thosecomposedofsinglespeciesofatoms,suchassilicon(Si)andgermanium(Ge)canbefoundinColumn4.however,numerouscompoundsemiconductorsarecomposedoftwoormoreelements.Forexample,galliumarsenide(G

4、aAs)isan3-5compoundthatisacombinationofgallium(Ga)fromColumn3andarsenic(As)fromColumn5.Priortotheinventionofthebipolarin1947,semiconductorswereusedonlyastwo-terminaldevices,suchasrectifiersandphotodiodes.Intheearly1950s,germaniumwasthemajorsemiconductormaterial.However,germaniumprovedunsuita

5、bleinmanyapplicationsbecausegermaniumdevicesexhibitedhighleakagecurrentsatonlymoderatelyelevatedtemperatures.Inaddition,germaniumoxideiswatersolubleandunsuitedfordevicefabrication.Sincetheearly1960ssiliconhasbecomeapracticalsubstituteandhasnowvirtuallysupplantedgermaniumasamaterialforsemicon

6、ductorfabrication.Themainreasonswenowusesiliconarethatsilicondevicesexhibitmuchlowerleakagecurrents,andhigh-qualitysilicondioxidecanbegrownthermally.Thereisalsoaneconomicconsideration.Siliconintheformofsilicaandsilicatescomprises25%oftheEarth’scrust,andsiliconissecondonlytooxygeninabundance.

7、Atpresent,siliconisoneofthemoststudiedelementsintheperiodictable;andsilicontechnologyisbyfarthemostadvancedamongallsemiconductortechnologies.Manyofthecompoundsemiconductorshaveelectricalandopticalpropertiesthatareabsentinsilicon.Theresemiconductors