Semiconductor physical electronics

708 Pages·2006·8.68 MB·English

by  Sheng S. Li

Semiconductor Physical Electronics
Sheng S. Li
Semiconductor
Physical Electronics
Second Edition
With230Figures
ShengS.Li
DepartmentofElectricalandComputerEngineering
UniversityofFlorida
Gainesville,FL32611–6130
USA
LibraryofCongressControlNumber:2005932828
ISBN10:0-387-28893-7
ISBN13:978-0387-28893-2
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Preface
Thepurposeofthesecondeditionofthisbookistoupdatethedevelopmentsin
varioussemiconductorandphotonicdevicessincethefirsteditionwaspublished
in1993.Duetotheadvancesinsemiconductortechnologiesoverthepastdecade,
manynewsemiconductordeviceshaveemergedandenteredthemarketplace.As
a result, a significant portion of the material covered in the original book has
been revised and updated. The intent of this book is to provide the reader with
a self-contained treatment of the fundamental physics of semiconductor materi-
als and devices. The author has used this book for a one-year graduate course
sequence taught for many years in the Department of Electrical and Computer
EngineeringoftheUniversityofFlorida.Itisintendedforfirst-yeargraduatestu-
dentswhomajoredinelectricalengineering.However,manystudentsfromother
disciplinesandbackgroundssuchaschemicalengineering,materialsscienceand
engineering,andphysicshavealsotakenthiscoursesequence.Thisbookmayalso
beusedasageneralreferenceforprocessinganddeviceengineersworkinginthe
semiconductorindustry.
Thepresentvolumecoversrelevanttopicsofbasicsolid-statephysicsandfun-
damentals of semiconductor materials and devices and their applications. The
mainsubjectscoveredincludecrystalstructures,latticedynamics,semiconductor
statistics,one-electronenergybandtheory,excesscarrierphenomenaandrecom-
binationmechanisms,carriertransportandscatteringmechanisms,opticalprop-
erties,photoelectriceffects,metal–semiconductorcontactsanddevices,p-njunc-
tiondiodes,bipolarjunctiontransistors(BJTs),heterojunctionbipolartransistors
(HBTs),MOSdevices(MOSFETs,CCDs),photonicdevices(solarcells,LEDs,
and LDs), quantum-effect devices (QWIPs, QDIPs, QW-LDs), and high-speed
III-Vsemiconductordevices(MESFETs,HEMTs,HETs,RTDs,TEDs).Thetext
presentsaunifiedandbalancedtreatmentofthephysicsofsemiconductormate-
rialsanddevices.Itisintendedtoprovidephysicistsandmaterialsscientistswith
more background on device applications, and device engineers with a broader
knowledgeoffundamentalsemiconductorphysics.
Thecontentsofthebookaredividedintotwoparts.InPartI(Chapters1–9),the
subjects of fundamental solid-state and semiconductor physics that are essential
forunderstandingthephysical,optical,andelectronicpropertiesofsemiconductor
v
vi Preface
materials are presented. Part II (Chapters 10–16) deals with the basic device
physics, device structures, operation principles, general characteristics, and ap-
plicationsofvarioussemiconductorandphotonicdevices.
Chapter1presentstheclassificationofsolids,crystalstructures,conceptofre-
ciprocallatticeandBrillouinzone,Millerindices,crystalbindings,anddefectsin
solids.Chapter2dealswiththethermalpropertiesandlatticedynamicsofcrys-
tallinesolids.Thelattice-specificheat,thedispersionrelationoflatticevibrations,
and the concept of phonons are also described. Chapter 3 is concerned with the
three basic semiconductor statistics. Derivation of Maxwell–Boltzmann (M-B),
Bose–Einstein (B-E), and Fermi–Dirac (F-D) distribution functions are given in
this chapter. Chapter 4 describes the elements of quantum concepts and wave
mechanics, the one-electron energy band theory, the effective mass concept for
electronsandholesinasemiconductor,theenergybandstructuresforelemental
andcompoundsemiconductors,andthedensity-of-statesfunctionsforbulksemi-
conductorsandlow-dimensionalsystemssuchassuperlattices,quantumwells,and
dots.Chapter5dealswiththeequilibriumpropertiesofintrinsicandextrinsicsemi-
conductors.Derivationofgeneralexpressionsforelectronandholedensities,and
discussionoftheshallow-anddeep-levelimpuritiesinsemiconductorsaregivenin
thischapter.Chapter6presentstherecombinationmechanismsandexcesscarrier
phenomenoninasemiconductor.Thebasicsemiconductorequations,whichgov-
ernthetransportofexcesscarriersinasemiconductor,aredescribedinthischapter.
Chapter7dealswiththederivationoftransportcoefficientsusingtheBoltzmann
equationandrelaxationtimeapproximation.Thelow-fieldgalvanomagnetic,ther-
moelectric, and thermomagnetic effects in n-type semiconductors are described
in this chapter. Chapter 8 is concerned with the scattering mechanisms and the
derivationofelectronmobilityinn-typesemiconductors.Therelaxationtimeand
mobilityexpressionsfortheionizedandneutralimpurityscatteringsandacoustical
andopticalphononscatteringsarederived.Chapter9presentstheopticalproperties
andphotoelectriceffectsinsemiconductors.Thefundamentalopticalabsorption
andfree-carrierabsorptionprocessesaswellasthephotoelectriceffectssuchas
photoconductive,photovoltaic,andphotomagnetoelectriceffectsinasemiconduc-
toraredepicted.Chapter10dealswiththebasictheoriesandrelevantelectronic
properties of metal–semiconductor contacts and their applications. The current
conductioninaSchottkybarrierdiode,methodsofdeterminingandenhancingthe
barrierheightsinaSchottkycontact,andohmiccontactsinasemiconductorare
presented.Chapter11presentsthebasicdevicetheoriesandcharacteristicsofap-n
junctiondiode.Thep-nheterojunctiondiodesandjunction-fieldeffecttransistors
(JFETs)arealsodiscussed.Chapter12isconcernedwiththedevicephysics,device
structures, and characteristics of various photovoltaic devices (solar cells), pho-
todetectors, and their applications. The solid-state light-emitting devices, which
includethelight-emittingdiodes(LEDs)andsemiconductordiodelasers(LDs)are
describedinChapter13.RecentadvancesinLEDsandLDsandtheirapplications
aregiveninthischapter.Chapter14dealswiththebasicdevicephysics,modeling,
andelectricalcharacteristicsofbipolarjunctiontransistors(BJTs),p-n-p-nfour-
layer devices (SCRs, thyristers), and heterojunction bipolar transistors (HBTs).
Preface vii
Chapter 15 presents the silicon-based metal-oxide-semiconductor (MOS) de-
vices.Thedevicephysicsandcharacteristicsforbothmetal-oxide-semiconductor
field-effect transistors (MOSFETs) and charge-coupled devices (CCDs) are de-
scribed. Finally, high-speed and high-frequency devices using GaAs and other
III-V compound semiconductors are discussed in Chapter 16. The GaAs-based
metal–semiconductorfield-effecttransistors(MESFETs),high-electron-mobility
transistors (HEMTs), hot-electron transistors (HETs), resonant tunneling diodes
(NTDs)andtransferredelectrondevices(TEDs)aredescribedinthischapter.
Throughoutthetext,theauthorstressestheimportanceofbasicsemiconductor
physicsanditsrelationtothepropertiesandperformanceofvarioussemiconductor
devices. Without a good grasp of the physical concepts and a good understand-
ingoftheunderlyingdevicephysics,itwouldbedifficulttotackletheproblems
encountered in material growth, device processing and fabrication, device char-
acterization, and modeling. The materials presented in this book should provide
asolidfoundationforunderstandingthefundamentallimitationsofvarioussemi-
conductormaterialsanddevices.Thisbookisespeciallyusefulforthosewhoare
interested in strengthening and broadening their basic knowledge of solid-state
andsemiconductordevicephysics.
Theauthorwouldliketoacknowledgehiswife,“Julie”Wen-FuShih,forher
support, love, and encouragement during the course of preparing this second
edition.
Contents
Preface.................................................................................... v
1. ClassificationofSolidsandCrystalStructure................................. 1
1.1 Introduction.................................................................... 1
1.2 TheBravaisLattice........................................................... 2
1.3 TheCrystalStructure......................................................... 6
1.4 MillerIndicesandCrystalPlanes.......................................... 9
1.5 TheReciprocalLatticeandBrillouinZone............................... 11
1.6 TypesofCrystalBindings................................................... 14
1.7 DefectsinaCrystallineSolid............................................... 18
Problems........................................................................ 23
Bibliography................................................................... 24
2. LatticeDynamics................................................................... 26
2.1 Introduction.................................................................... 26
2.2 TheOne-DimensionalLinearChain....................................... 27
2.3 DispersionRelationforaThree-DimensionalLattice.................. 33
2.4 TheConceptofPhonons..................................................... 36
2.5 TheDensityofStatesandLatticeSpectrum............................. 37
2.6 LatticeSpecificHeat.......................................................... 39
Problems........................................................................ 42
References...................................................................... 44
Bibliography................................................................... 44
3. SemiconductorStatistics.......................................................... 45
3.1 Introduction.................................................................... 45
3.2 Maxwell–BoltzmannStatistics............................................. 46
3.3 Fermi–DiracStatistics........................................................ 50
3.4 Bose–EinsteinStatistics...................................................... 56
3.5 StatisticsfortheShallow-ImpurityStatesin
aSemiconductor............................................................... 57
ix
x Contents
Problems........................................................................ 59
Bibliography................................................................... 60
4. EnergyBandTheory............................................................... 61
4.1 Introduction................................................................... 61
4.2 BasicQuantumConceptsandWaveMechanics....................... 62
4.3 TheBloch–FloquetTheorem.............................................. 66
4.4 TheKronig–PenneyModel................................................ 67
4.5 TheNearlyFreeElectronApproximation............................... 74
4.6 TheTight-BindingApproximation....................................... 80
4.7 EnergyBandStructuresforSomeSemiconductors................... 86
4.8 TheEffectiveMassConceptforElectronsandHoles................ 93
4.9 EnergyBandStructuresandDensityofStates
forLow-DimensionalSystems............................................ 96
Problems....................................................................... 101
References.................................................................... 103
Bibliography.................................................................. 103
5. EquilibriumPropertiesofSemiconductors.................................... 105
5.1 Introduction................................................................... 105
5.2 DensitiesofElectronsandHolesinaSemiconductor................ 106
5.3 IntrinsicSemiconductors................................................... 113
5.4 ExtrinsicSemiconductors.................................................. 116
5.5 IonizationEnergiesofShallow-andDeep-LevelImpurities........ 123
5.6 HallEffect,ElectricalConductivity,andHallMobility ............. 125
5.7 HeavyDopingEffectsinaDegenerateSemiconductor.............. 128
Problems....................................................................... 130
References.................................................................... 132
Bibliography.................................................................. 133
6. ExcessCarrierPhenomenoninSemiconductors.............................. 134
6.1 Introduction................................................................... 134
6.2 NonradiativeRecombination:TheShockley–Read–HallModel... 135
6.3 Band-to-BandRadiativeRecombination................................ 140
6.4 Band-to-BandAugerRecombination.................................... 142
6.5 BasicSemiconductorEquations.......................................... 146
6.6 TheCharge-NeutralityEquation.......................................... 149
6.7 TheHaynes–ShockleyExperiment....................................... 151
6.8 ThePhotoconductivityDecayExperiment ............................. 154
6.9 SurfaceStatesandSurfaceRecombinationVelocity.................. 159
6.10 Deep-LevelTransientSpectroscopyTechnique........................ 162
6.11 SurfacePhotovoltageTechnique.......................................... 165
Problems....................................................................... 169
References.................................................................... 170
Bibliography.................................................................. 170
Contents xi
7. TransportPropertiesofSemiconductors...................................... 171
7.1 Introduction................................................................. 171
7.2 Galvanomagnetic,Thermoelectric,andThermomagnetic
Effects........................................................................ 173
7.3 BoltzmannTransportEquation.......................................... 180
7.4 DerivationofTransportCoefficientsfor
n-typeSemiconductors.................................................... 182
7.5 TransportCoefficientsfortheMixedConductionCase............. 195
7.6 TransportCoefficientsforSomeSemiconductors.................... 198
Problems..................................................................... 208
References................................................................... 209
Bibliography................................................................ 210
8. ScatteringMechanismsandCarrierMobilitiesinSemiconductors...... 211
8.1 Introduction................................................................. 211
8.2 DifferentialScatteringCross-Section.................................. 214
8.3 IonizedImpurityScattering.............................................. 217
8.4 NeutralImpurityScattering.............................................. 221
8.5 AcousticalPhononScattering............................................ 222
8.6 OpticalPhononScattering................................................ 228
8.7 ScatteringbyDislocations................................................ 230
8.8 ElectronandHoleMobilitiesinSemiconductors.................... 231
8.9 Hot-ElectronEffectsinaSemiconductor.............................. 239
Problems..................................................................... 243
References................................................................... 244
Bibliography................................................................ 244
9. OpticalPropertiesandPhotoelectricEffects................................. 246
9.1 Introduction................................................................. 246
9.2 OpticalConstantsofaSolid.............................................. 247
9.3 Free-CarrierAbsorptionProcess........................................ 252
9.4 FundamentalAbsorptionProcess....................................... 256
9.5 ThePhotoconductivityEffect............................................ 264
9.6 ThePhotovoltaic(Dember)Effect...................................... 275
9.7 ThePhotomagnetoelectricEffect........................................ 277
Problems..................................................................... 281
References................................................................... 283
Bibliography................................................................ 283
10. Metal–SemiconductorContacts................................................ 284
10.1 Introduction................................................................. 284
10.2 MetalWorkFunctionandSchottkyEffect............................ 285
10.3 ThermionicEmissionTheory............................................ 288
10.4 IdealSchottkyContact.................................................... 290
10.5 CurrentFlowinaSchottkyDiode...................................... 295