固体物理导论-4.ppt

Great Experimentalist http:/ we can learn from them:The method/design of experiments TodaysOutlinePhoton（光子）Phonon（声子）LetstalkaboutLightGod said,Let there be light;and there was lightFor a physicist 詹姆斯詹姆斯克拉克克拉克麦克斯韦麦克斯韦 James Clerk Maxwell18311879从牛顿到爱因斯坦这一整个阶段中最伟大的理论物理学家建立了麦克斯韦方程组创立了经典电磁学预言了电磁波的存在提出了光的电磁说运用数学工具分析物理问题和精确地表述科学思想的大师Light is Electromagnetic Wave“麦克斯韦在潜心研究了法拉第关于电磁学方面的新理论和思想之后，坚信法拉第的新理论包含着真理。于是他抱着给法拉第的理论“提供数学方法基础”的愿望，决心把法拉第的天才思想以清晰准确的数学形式表示出来。”1888年德国物理学家赫兹用实验验证了电磁波的存在Solar SpectrumPhotoelectric Effect材料铯钠锌银铂极限波长652nm540nm372nm260nm196nmWorkFunction（电子溢出功）EvacuumEF,workfunction波粒二象性（wave-particleduality）RadiationQuantizationQuantizedRadiation:Photonh:普朗克常数(6.626x1034Js)红光：650nm，1.97eVE=h=c/Photo-excitation/RadiationexcitationRadiative/Non-radiativeRecombinationPhoto-ElectroninteractionPhotogenerationFundamentalsforphotodetectorsandsolarcellsRadiativerecombinationFundamentalsforLightEmittingDiodes(LED)andLasersBreak!PhononQuantizedlatticevibrationAtomicvibrationatroomtemperature:1Vibrationhasdifferentmodes:PhononmodesEnergyofphonons:E=hDensityofStatefunctionforelectronsDispersionRelation:densityofphononmodesDifferentphononmodesLA:longitudinalacousticTA:TransverseacousticLO:longitudinalopticalTO:TransverseopticalE=hPhonon-PhotoninteractionEmissionofphoton,thermalradiationAbsorptionofphoton,heatingoflatticeTheoriesnotclearPhonon-ElectroninteractionPhononscatteringofcarriers精品精品课件件！精品精品课件件！ConservationofenergyandmomentumPhotonlargeenergy,verylittermomentumRoomtemperaturePhonon:largemomentum,littleenergyElectronlargeenergy,largemomentum