Subject I 科技英语课件

课程性质：学科基础选修课学分：3科技英语EnglishforScience&Technology(EST)张继军Email:[e-mail]:上海大学宝山校区东区材料大楼314室课程目标•扩大半导体材料与器件方向专业词汇量•提高阅读科技文献的理解能力•提高中英文翻译能力•提高英文写作能力CharacteristicsofEST科技英语的特点Objectivity(客观)thepassivevoice(被动语态),thethird/secondperson(第三/二人称)Conciseness/Clarity(简洁)Precise(精确)Sometypicalsentencepatterns,alargenumberoftechnicalandsemi-technicaltermsReferences半导体器件导论（AnIntroductiontoSemiconductorDevices）(DonaldA.Neamen，清华大学出版社)Photovoltaics:Devices,SystemsandApplicationsfromUniversityofNewSouthWales科技英语语法高级教程（西安电子科技大学出版社，秦荻辉编著）科技英语论文实用写作指南（俞炳丰,西安交通大学出版社2003)RelativenewsandarticlesoninternetOutlineofthiscourseSubjectI:CrystalstructureofsolidsSubjectII:TheoryofsolidsSubjectIII:TranslationSubjectIV:CarriertransportandexcesscarrierphenomenaSubjectV:ThepnjunctionSubjectVI:Themetal-oxide-semiconductorfield-effecttransistor(MOSFET)SubjectVII:DevicefabricationtechniquesSubjectVIII:EfficientreadingandWritingSubjectIX:Opticaldevices---Solarcell,LEDSubjectX:OverviewSubject1:Crystallinestructureofsolids1.1SemiconductorMaterialsSemiconductorsareagroupofmaterialshavingconductivities(电导率)betweenthoseofmetalsandinsulators.Twogeneralclassificationofsemiconductorsaretheelementalsemiconductor(元素半导体)materials,foundingroupIVoftheperiodictable(元素周期表),andthecompoundsemiconductor(化合物半导体)materials,mostofwhichareformedfromspecialcombinations(化合)ofgroupIIIandgroupVelements.1.2TypesofSolidsAmorphous(非晶),polycrystalline(多晶),andsinglecrystal(单晶)arethethreegeneraltypesofsolids.Eachtypeischaracterizedbythesizeofanorderedregion(有序化区域)withinthematerial.Anorderedregionisaspatialvolume(空间范围)inwhichatomsormoleculeshavearegulargeometricarrangementorperiodicity.Amorphousmaterialshaveorderonlywithinafewatomicormoleculardimensions(尺度),whilepolycrystallinematerialshaveahighdegreeoforderovermanyatomicormoleculardimensions.Theseorderedregions,orsingle-crystalregions,varyinsizeandorientationwithrespecttooneanother.Thesingle-crystalregionsarecalledgrains(晶粒)andareseparatedfromoneanotherbygrainboundaries(晶界).Single-crystalmaterialshaveahighdegreeofregulargeometricperiodicitythroughouttheentirevolumeofthematerial.Theadvantageofasingle-crystalmaterialisthat,ingeneral,itselectricalpropertiesaresuperiortothoseofnonsingle-crystalmaterial,sincegrainboundariestendtodegradetheelectricalcharacteristics.1.3Atomicbonding(原子价键)Theatomsatthetwoextremes(端)oftheperiodictable(周期表)(exceptingtheinertelements(惰性元素))tendtoloseorgainvalenceelectrons(价带电子),thusformingions.TheseelementsingroupIoftheperiodictabletendtolosetheironeelectronandbecomepositivelycharged(带正电),whiletheelementsingroupVIItendtogainanelectronandbecomenegativelycharged.Theseoppositelychargedionsthenexperience(通过)acoulombattraction(库伦吸引)andformabondreferredtoasanionicbond(离子键).Anotheratomicbondthattendstoachievecolsed-valenceenergyshells(满价带能量壳层)iscovalentbond(共价键),anexampleofwhichisfoundinthehydrogenmolecule.Ahydrogenatomhasoneelectronandneedsonemoreelectrontocompletethelowestenergyshell(最低能量壳层).Covalentbondresultsinelectronsbeingsharedbetweenatoms,sothatthevalenceshell(价电子层)ofeachatomisfull.covalentbond1.4Imperfections(缺陷)inSolidsOnetypeofimperfectionthatallcrystalshaveincommonisatomicthermalvibration(热振动).Aperfectsinglecrystalcontainsatomsatparticularlatticesites,theatomsseparatedfromeachotherbyadistancewehaveassumedtobeconstant.Theatomsincrystal,however,haveacertainthermalenergy(热能),whichisafunction(函数)oftemperature.Thethermalenergycausestheatomstovibrate(振动)inarandommanneraboutanequilibriumlatticepoint(晶格点).Thisrandom(随机的)thermalmotioncausesthedistancebetweenatomstorandomlyfluctuate,slightlydisruptingtheperfectgeometricarrangementofatoms.Thisimperfection,calledlatticevibrations(晶格振动),affectssomeelectricalparametersofsemiconductormaterials.Anothertypeofdefectiscalledapointdefect(点缺陷).Inanidealsingle-crystallattice,theatomsarearrangedinaperfectperiodicarrangement.However,inarealcrystal,anatommaybemissingfromaparticularlatticesite.Thisdefectisreferredto(称为)asavacancy(空位).Inanothersituation,anatommaybelocatedbetweenlatticesites.Thisdefectisreferredtoasaninterstitial(间隙).Thepointdefectsinvolvesingleatomsorsingle-atomlocations.Informingsingle-crystalmaterials,morecomplexdefectsmayoccur.Alinedefect(线缺陷),forexample,occurswhenanentirerowofatomsismissingfromitsnormallatticesite.Thisdefectisreferredtoasalinedislocation(线位错).1.5ImpuritiesinSolidsForeignatoms,orimpurityatoms,maybepresentinacrystallattice.Impurityatomsmaybelocatedatnormallatticesites,inwhichcasetheyarecalledsubstitutionalimpurities(替位杂质).Impurityatomsmayalsobelocatedbetweennormalsites,inwhichcasetheyarecalledinterstitialimpurities(间隙杂质).Byaddingcontrolledamountsofparticularimpurityatoms,theelectricalcharacteristicsofasemiconductormaterialcanbealtered.Thetechniqueofaddingimpurityatomstoasemiconductormaterialtochangeitsconductivityiscalleddoping(掺杂).Therearetwogeneralmethodsofdoping:Dopingdiffusion(杂质扩散)andionimplantation(离子注入).1.6Growthofsemiconductormaterials1.6.1Growthfrommelt(熔体法生长)Acomm