Semiconductor Heterojunctions and Nanostructures Omar Manasreh UniversityofArkansas Fayetteville,Arkansas McGraw-Hill NewYork Chicago SanFrancisco Lisbon London Madrid MexicoCity Milan NewDelhi SanJuan Seoul Singapore Sydney Toronto Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-146968-0 The material in this eBook also appears in the print version of this title: 0-07-145228-1. All trademarks are trademarks of their respective owners. Rather than put a trademark symbol after every occurrence of a trademarked name, we use names in an editorial fashion only, and to the benefit of the trademark owner, with no intention of infringement of the trademark. 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If you’d like more information about this book, its author, or related books and websites, please click here. 555 TomyPhDadvisor,DonO.Pederson andmyfriendGregJ.Salamowhoinspiredmein manyways ABOUTTHEAUTHOR OmarManasreh,Ph.D.,isafullprofessorintheDepartment ofElectricalEngineeringattheUniversityofArkansasin Fayettevilleandtheauthorofover150journalarticles.He editedandcoeditedovertenbooksandorganizedoverten symposia.Dr.Manasrehisalsoaserieseditorforatechnical bookseries,NanoscienceandTechnology,publishedby McGraw-Hill.Hehasextensiveexperienceinthe experimentalandtheoreticaloptoelectronicpropertiesof III-Vsemiconductors,superlattices,nanostructures,and relateddevices. Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use. For more information about this title, click here Contents Preface xi Acknowledgments xv ListofSymbolsandAbbreviations xvi Chapter1. IntroductiontoQuantumMechanics 1 1.1 Introduction 1 1.1.1 Blackbodyradiation 2 1.1.2 Thespecificheatcapacityofsolids 2 1.1.3 Photoelectriceffect 4 1.1.4 TheBohrmodeloftheatom 6 1.2 ThedeBroglieRelation 8 1.3 WaveFunctionsandtheSchro¨dingerEquation 9 1.4 WavePacketataGivenTime 10 1.5 SeparationofVariables 15 1.6 DiracNotation 17 1.7 ImportantPostulates 18 1.8 ImportantMathematicalTools 19 1.8.1 Thescalarproduct 19 1.8.2 Linearoperators 20 1.8.3 Actionofalinearoperatoronabra 21 1.8.4 TheadjointoperatorA†ofalinearoperatorA 21 1.8.5 Eigenvaluesandeigenfunctionsofanoperator 22 1.8.6 TheDiracδ-function 24 1.8.7 FourierseriesandFouriertransforminquantummechanics 26 1.9 VariationalMethod 28 1.10 Perturbation 29 1.11 AngularMomentum 33 Summary 34 Problems 35 Chapter2. PotentialBarriersandWells 37 2.1 StationaryStatesofaParticleinaPotentialStep 38 2.2 PotentialBarrierwithaFiniteHeight 42 2.3 PotentialWellwithanInfiniteDepth 49 v vi Contents 2.4 Finite-DepthPotentialWell 51 2.5 Unbound Motion of a Particle ( E >Vo) in a Potential Well with a FiniteDepth 56 2.6 TriangularPotentialWell 58 2.7 Parabolic Potential Well 61 2.8 Delta-FunctionPotentials 64 2.9 TransmissioninFiniteDouble-BarrierPotentialWells 70 2.10 Wentzel-Kramers-Brillouin(WKB)Approximation 72 2.11 EnergyLevelsinDoubleQuantumWellStructure 78 Summary 80 Problems 81 Chapter3. ElectronicEnergyLevelsinPeriodicPotentials 83 3.1 Bloch’sTheorem 84 3.2 TheKronig-PenneyModel 85 3.3 BlochElectroninaWeakPeriodicPotential 89 3.4 One-ElectronApproximationinaPeriodicDiracδ-functions 93 3.5 Superlattices 95 3.6 EffectiveMass 98 3.7 BandStructureCalculationMethods 99 3.7.1 Tight-bindingmethod 99 3.7.2 k·pmethod 102 3.7.3 Envelopefunctionapproximation 113 Summary 119 Problems 120 Chapter4. TunnelingThroughPotentialBarriers 123 4.1 TransmissionThroughPotentialBarriers 124 4.2 TunnelingThroughPyramidalPotentialBarriers 131 4.3 Double-BarrierPotential 135 4.4 The pn-JunctionTunnelingDiode 139 4.5 ResonantTunnelingDiodes 143 4.6 CoulombBlockade 147 Summary 149 Problems 150 Chapter5. DistributionFunctionsandDensityofStates 153 5.1 DistributionFunctions 156 5.2 Maxwell-BoltzmannStatistic 157 5.3 Fermi-DiracStatistics 161 5.4 Bose-EinsteinStatistics 164 5.5 DensityofStates 166 5.6 DensityofStatesofQuantumWells,Wires,andDots 171 5.6.1 Quantumwells 171 5.6.2 Quantumwires 175 5.6.3 Quantumdots 178 Contents vii 5.7 DensityofStatesofOtherSystems 179 5.7.1 Superlattices 179 5.7.2 Densityofstatesofbulkelectronsinthepresenceofa magneticfield 181 5.7.3 Densityofstatesinthepresenceofanelectricfield 184 Summary 188 Problems 189 Chapter6. OpticalProperties 191 6.1 Fundamentals 192 6.2 LorentzandDrudeModels 196 6.3 TheOpticalAbsorptionCoefficientoftheInterbandTransition inDirectBandgapSemiconductors 199 6.4 TheOpticalAbsorptionCoefficientoftheInterbandTransition inIndirectBandgapSemiconductors 205 6.5 TheOpticalAbsorptionCoefficientoftheInterbandTransition inQuantumWells 206 6.6 TheOpticalAbsorptionCoefficientoftheInterbandTransition inTypeIISuperlattices 208 6.7 TheOpticalAbsorptionCoefficientoftheIntersubbandTransition inMultipleQuantumWells 210 6.8 TheOpticalAbsorptionCoefficientoftheIntersubbandTransition inGaN/AlGaNMultipleQuantumWells 216 6.9 ElectronicTransitionsinMultipleQuantumDots 217 6.10 SelectionRules 222 6.10.1 Electron-photoncouplingofintersubbandtransitions inmultiplequantumwells 222 6.10.2 Intersubbandtransitioninmultiplequantumwells 223 6.10.3 Interbandtransition 223 6.11 Excitons 225 6.11.1 Excitonsinbulksemiconductors 225 6.11.2 Excitonsinquantumwells 231 6.11.3 Excitonsinquantumdots 233 6.12 CyclotronResonance 234 6.13 Photoluminescence 239 6.14 LatticeVibrationsandPhonons 245 Summary 255 Problems 256 Chapter7. ElectricalandTransportProperties 261 7.1 Introduction 261 7.2 TheHallEffect 265 7.3 QuantumHallandShubnikov–deHaasEffects 269 7.3.1 Shubnikov–deHaaseffect 272 7.3.2 QuantumHalleffect 275 7.4 ChargeCarrierTransportinBulkSemiconductors 277 7.4.1 Driftcurrentdensity 278 7.4.2 Diffusioncurrentdensity 282 7.4.3 Generationandrecombination 286 7.4.4 Continuityequation 288 viii Contents 7.5 BoltzmannTransportEquation 294 7.6 DerivationofTransportCoefficientsUsingtheBoltzmann TransportEquation 298 7.6.1 Electricalconductivityandmobilityinn-typesemiconductors 300 7.6.2 HallcoefficientRH 302 7.7 ScatteringMechanismsinBulkSemiconductors 304 7.7.1 Scatteringfromanionizedimpurity 306 7.7.2 Scatteringfromaneutralimpurity 307 7.7.3 Scatteringfromacousticphonons 307 7.7.4 Opticalphononscattering—polarandnonpolar 309 7.7.5 Scatteringfromshort-rangepotentials 310 7.7.6 Scatteringfromdipoles 311 7.8 ScatteringinaTwo-DimensionalElectronGas 312 7.8.1 Scatteringbyremoteionizedimpurities 314 7.8.2 Scatteringbyinterfaceroughness 315 7.8.3 Electron-electronscattering 317 7.9 CoherenceandMesoscopicSystems 318 Summary 324 Problems 325 Chapter8. SemiconductorGrowthTechnologies:Bulk,ThinFilms, andNanostructures 329 8.1 Introduction 329 8.2 GrowthofBulkSemiconductors 334 8.2.1 Liquid-encapsulatedCzochralski(LEC)method 334 8.2.2 HorizontalBridgmanmethod 341 8.2.3 Float-zonegrowthmethod 343 8.2.4 Lelygrowthmethod 346 8.3 GrowthofSemiconductorThinFilms 347 8.3.1 Liquid-phaseepitaxymethod 348 8.3.2 Vapor-phaseepitaxymethod 349 8.3.3 Hydridevapor-phaseepitaxialgrowthofthickGaNlayers 352 8.3.4 Pulsed-laserdepositiontechnique 355 8.3.5 Molecularbeamepitaxygrowthtechnique 357 8.3.6 Metal-organicchemicalvapordepositiongrowthtechnique 372 8.4 FabricationandGrowthofQuantumDots 377 8.4.1 Nucleation 379 8.4.2 Fabricationsofquantumdots 387 8.4.3 Epitaxialgrowthofself-assemblyquantumdots 388 Summary 399 Problems 400 Chapter9. ElectronicDevices 403 9.1 Introduction 403 9.2 SchottkyDiode 406 9.3 Metal-SemiconductorField-EffectTransistors 411 9.4 JunctionField-EffectTransistor 420 9.5 HeterojunctionField-EffectTransistors 423 9.6 GaN/AlGaNHeterojunctionField-EffectTransistors 428 9.7 HeterojunctionBipolarTransistors 433