《半导体材料与技术》cha课件.pptx

Chapter2ElectricalandThermalConductioninSolid2.1Classicaltheory:TheDrudemodel(德鲁特模型)2.2Temperaturedependenceofresistivity:idealpuremetals(电阻对时间的依赖性：理想纯金属)2.3Matthiessen’sandNordheim’srules(马西森和诺德海姆定则)2.4Resistivityofmixturesandporousmaterials(混合物和孔洞材料的电阻率)2.5TheHalleffectandHalldevices(霍尔效应和霍尔器件)2.6Thinmetalfilms(金属薄膜)2.7Thermalconduction(热传导)2.8Electricalconductivityofnonmetals(非金属的电导)FromPrinciplesofelectronicMaterialsDevices,SOKasap(McGraw-Hill,2005)

Content?Electricalconductioninvolvesthemotionofchargesinamaterialundertheinfluenceofanappliedfield.?Amaterialcangenerallybeclassifiedasaconductorifitcontainsalargenumberof‘free’ormobilechargecarriers.?Inmetals,thevalenceelectronsthatarefreetomovewithinthemetalarecalledasconductionelectrons.?Objectivesofelectricalconduction:conductionelectrons;accelerationoffreechargecarriers;driftvelocity(漂移速度);electroncollisions(碰撞)withlatticevibrations(晶格振动),crystaldefects,impurities(杂质)etc.?Thermalconductioninsolid

2.1Classicaltheory:theDrudemodelTheelectriccurrentdensityJisdefinedas:Driftvelocityinthexdirection(averageoverNelectrons):漂移速度Driftofelectronsinaconductorinthepresenceofanappliedelectricfield.

2.1Classicaltheory:theDrudemodelThenumberofelectronsperunitvolumen:Electronsdriftwithanaveragevelocityvdxinthexdirection.(Existheelectricfield.)

Aconductionelectronintheelectrongasmovesaboutrandomlyinametal(withameanspeedu)beingfrequentlyandrandomlyscatteredbythermalvibrationsoftheatoms.Intheabsenceofanappliedfieldthereisnonetdriftinanydirection.0102

Inthepresenceofanappliedfield,Ex,thereisanetdriftalongthex-direction.Thisnetdriftalongtheforceofthefieldissuperimposed(叠加)ontherandommotionoftheelectron.Aftermanyscatteringeventstheelectronhasbeendispl