Polarization Effects in Semiconductors: From Ab InitioTheory to Device Applications

522 Pages·2008·19.62 MB·English

by  Piotr Boguslawski

Polarization Effects
in Semiconductors
From Ab InitioTheory
to Device Applications
Colin Wood Debdeep Jena
•
Editors
Polarization Effects
in Semiconductors
From Ab InitioTheory
to Device Applications
123
Colin Wood Debdeep Jena
US Office of Naval Research University of Notre Dame
Arlington, VA Notre Dame, IN
USA USA
Library of Congress Control Number: 2007932418
ISBN 978-0-387-36831-3 e-ISBN 978-0-387- 68319-5
Printedonacid-freepaper.
c 2008SpringerScience+BusinessMedia,LLC
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Preface
In the last two decades basic semiconductor research has increasingly focussed
attention away from cubic crystal III-V and II-VI compounds toward the “wide-
bandgapsemiconductors”Ga,Al,Inbinaryandternarynitrides,andsiliconcarbide.
Thesesmalleranioncompoundspackmoredenselyinhexagonalcrystals,withthe
consequenceofveryhighspontaneousanddeformationinducedelectrostaticpolar-
ization.
Theimportanceandpotentialfunctionalityofwasrapidlyrecognizedinthelate
1990s. In 2000 the Multi-disciplinary University Research Initiative (MURI) of
“Polarization Effects in Wide Bandgap Semiconductors” was initiated by the Of-
fice of Naval Research to accelerate and consolidate understanding, engineering
anddevice applicationof the extra electro-physicalparameterspace. Thewinning
program,“Polaris”byteamscenteredatUCSanDiego,andCornellUniversity,was
oneofthemostproductiveinthehistoryoftheMURIprogram,andistestamentto
thevalueofsponsoredcollaborativeresearchsoardentlydefendedbytheDirector
ofDefenseResearchandEngineering(DDR&E)OfficeoftheSecretaryofDefense
(OSD).
Electronicpolarizationhasprofoundconsequencesontheelectrostaticsandelec-
trodynamics of epitaxial films and heterostructures. Polaris team members devel-
opedacomprehensivescientificunderstandingandmademanyconceptualadvances
inpolarization-relatedsemiconductorphysics.Asaresult,manyelectronicandop-
ticaldeviceshavebeensignificantlyimprovedandnoveldevicesconceivedandre-
alized.
This book is an attempt to ensure that the pioneering advances of the Polaris
investigatorsare collected and expandedto allow efficient recognition and under-
standingofthemanynewscientificandengineeringprinciples,considerationsand
applicationsdevelopedinthe5yearprogram.
Eachchapteraddressesaspectsofpolarizationeffectsfroma differentperspec-
tive, and for differentpurposes.There is some overlapin the introductorycontent
in several chapters, albeit each with its own unique flavor. The editors decided to
retain this formatas it serves to make each chapterself-contained,so that readers
v
vi Preface
have the optionof perusingthem independentlywithoutloss of continuity,and to
guidereadersmoreeffectivelytothesubtledifferencesinperspectives.
Arlington,VA ColinWood
NotreDame,IN DebdeepJena
Contributors
P.Alpay
MaterialsScienceandEngineeringProgram& Instituteof MaterialsSciences,
UniversityofConnecticut,Storrs,CT06269USA,e-mail:[email protected]
O.Ambacher
InstituteofMicro-andNanotechnologies,TechnicalUniversityIlmenau,D-98693
Ilmenau,Germany,e-mail:[email protected]
P.M.Asbeck
Departmentof ElectricalandComputerEngineering,UniversityofCalifornia,
SanDiego,CA92093USA,e-mail:[email protected]
J.Bernholc
CenterforHighPerformanceSimulation&DepartmentofPhysics,NorthCarolina
StateUniversity,Raleigh,NC27695,USA,e-mail:[email protected]
P.Boguslawski
Institue of Physics, Polish Academyof Sciences, Al. Lotnikow32/46,02-668
Warsaw,Poland,e-mail:[email protected]
R.Butte´
LaboratoryofAdvancedSemiconductorsforPhotonicsandElectronics(LASPE),
EPFL,Station3,CH-1015,Lausanne,Switzerland,e-mail:raphael.butte@epfl.ch
M.V.S.Chandrashekhar
ElectricalandComputerEngineering,CornellUniversity,Ithaca,NY14853,USA,
e-mail:[email protected]
V.Cimalla
InstituteofMicro-andNanotechnologies,TechnicalUniversityIlmenau,D-98693
Ilmenau,Germany,e-mail:[email protected]
N.Grandjean
LaboratoryofAdvancedSemiconductorsforPhotonicsandElectronics(LASPE),
vii
viii Contributors
EPFL,Station3,CH-1015,Lausanne,Switzerland,
e-mail:nicolas.grandjean@epfl.ch
D.Jena
DepartmentofElectricalEngineering,UniversityofNotreDame,NotreDame,IN
46556USA,e-mail:[email protected]
G.Koley
DepartmentofElectricalEngineering,UniversityofSouthCarolina,Columbia,SC
29208,USA,e-mail:[email protected]
J.Leach
Departmentof ElectricalandComputerEngineering,VirginiaCommonwealth
University,Richmond,VA23284,USA,e-mail:[email protected]
J.Mantese
UnitedTechnologiesResearchCenter,411SilverLane,MS129-45,EastHartford,
CT06108,USA,e-mail:[email protected]
H.Morkoc¸
Departmentof ElectricalandComputerEngineering,VirginiaCommonwealth
University,Richmond,VA23284,USA,e-mail:[email protected]
J.Singh
Electrical Engineeringand Computer Science Dept. University of Michigan,
AnnArbor,MI48109,USA,e-mail:[email protected]
M.Singh
Electrical Engineeringand Computer Science Dept. University of Michigan,
AnnArbor,MI48109,USA,e-mail:[email protected]
M.G.Spencer
ElectricalandComputerEngineeringDept.CornellUniversity,Ithaca,NY14853,
USA,e-mail:[email protected]
C.I.Thomas
ElectricalandComputerEngineeringDept.CornellUniversity,Ithaca,NY14853,
USA,e-mail:[email protected]
Y.-R.Wu
AssistantProfessor,NationalTaiwanUniversity,GraduateInstituteofPhotonics
andOptoelectronicsandDepartmentofElectricalEngineering,MD617,No1.
RooseveltRoadSec.4,Taipei10617,Taiwan,e-mail:[email protected]
E.T.Yu
ElectricalandComputerEngineeringDept.UniversityofCalifornia,SanDiego,
CA92093USAe-mail:[email protected]
Contents
TheoreticalApproachtoPolarizationEffectsinSemiconductors........ 1
PiotrBoguslawskiandJ.Bernholc
1 Introduction.............................................. 1
2 BasicElectrostatics........................................ 2
3 Polarization .............................................. 4
4 AbInitioCalculationsoftheElectronicStructure............... 5
5 ModernTheoryofPolarization.............................. 6
6 PolarizationatInterfaces:InterfaceDipoles ................... 10
6.1 AveragingMicroscopicChargesandField............. 10
6.2 AlAs/GaAsSuperlattice ............................ 11
7 SpontaneousPolarizationintheWurtziteStructure:BeO ........ 12
8 GaN/AlN Superlattice: Spontaneous Polarization
andPiezoelectricity ....................................... 13
9 ElectricField-DrivenDiffusionandSegregationofDopants
inSuperlattices ........................................... 16
9.1 Introduction ...................................... 16
9.2 InterfacialSegregation ............................. 17
9.3 ProfileofHinAlN/GaNSuperlattice................. 19
10 Summary ................................................ 23
References..................................................... 24
PolarizationInducedEffectsinGaN-basedHeterostructuresandNovel
Sensors ........................................................ 27
O.AmbacherandV.Cimalla
1 Introduction.............................................. 27
2 First-PrinciplesPredictionofStructuralandPyroelectricProperties 29
3 Lattice Constants, AverageBondLengthand BondAngles
inTernaryCompounds..................................... 30
4 Polarity.................................................. 40
5 GrowthofUndopedAlGaN/GaN,InGaN/GaNandAlInN/GaN
Hetero-andNanostructures................................. 41
ix
x Contents
5.1 AlGaN/GaNHeterostructures ....................... 41
5.2 InGaN/GaNHeterostructures........................ 42
5.3 AlInN/GaNHeterostructures ........................ 42
6 Non-Linear Spontaneousand Piezoelectric Polarization
inGroup-III-Nitrides ...................................... 42
6.1 SpontaneousPolarization........................... 43
6.2 PiezoelectricPolarization........................... 45
7 PolarizationInducedSurfaceandInterfaceCharges............. 56
8 SheetCarrierConcentrationofPolarizationInduced2DEGs ..... 61
8.1 2DEGsConfinedatInterfacesofUndopedGa-face
AlGaN/GaNHeterostructures ....................... 63
8.2 2DEGsConfinedatInterfacesofUndoped,Ga-face
AlInN/GaNHeterostructures ........................ 65
8.3 2DEGsConfinedinInGaN/GaNSingleQuantumWells . 69
9 SensorsBasedonPolarizationInduced2DEGs ................ 74
9.1 Overview ........................................ 74
9.2 SurfaceSensitiveSensors........................... 75
9.3 MechanicalSensors................................ 92
9.4 SensorforElectromagneticFields.................... 98
10 Summary ................................................100
References.....................................................103
Lateral and Vertical Charge Transport in Polar Nitride
Heterostructures: ............................................... 111
Yuh-RennWu,MadhusudanSingh,andJaspritSingh
1 PolarHeterostructures:WhatDoTheyOffer?..................111
1.1 PolarHeterostructures:UndopedElectronics...........112
1.2 TheApplicationsofNitrides ........................113
1.3 TransportIssuesinNitrideDevice ...................115
1.4 PolarMaterials:UseinSensorTechnology–Potential
ofMergingPolarMaterialswithSemiconductors.......115
2 TheoreticalApproach......................................117
2.1 PolarizationbyStrain ..............................117
2.2 VerticalJunctionTransport..........................119
2.3 LateralTransportinUndopedHEMTs ................123
2.4 k·p Methodfor Strained Nitride QuantumWells
andQuantumDots.................................127
3 TailoringofVerticalJunctions...............................128
3.1 GateLeakageSuppression..........................129
3.2 FormingOhmicContactsbyUsingPolarizationEffects..132
4 NitrideHFETS:TransportIssues ............................134
4.1 NonlinearAccessResistanceandGaNDeviceOperation 135
4.2 ScalingIssuesinNitrideHEMTs ....................139
5 SmartHFETs:Multi-FunctionalDevices......................142
5.1 StressandStrainCalculation ........................145
5.2 Pyroelectricity ....................................146
Contents xi
5.3 StrainSensorFETs:Results.........................147
5.4 ThermalSensorFETs..............................150
5.5 EffectsofDefects .................................152
6 Conclusions..............................................154
References.....................................................154
PolarizationEffectsonLow-FieldTransport&MobilityinIII-VNitride
HEMTs........................................................ 161
DebdeepJena
1 Introduction..............................................161
2 Polarization-Induced2DEGsinAlGaN/GaNHEMTs ...........163
2.1 PolarizationEffectsonChargeTransportandScattering .163
2.2 ChargeControl ...................................164
2.3 SurveyofExperimental2DEGMobilityData ..........169
2.4 TheoreticalTools to AddressAlGaN/GaN 2DEG
Mobilities........................................171
3 ScatteringMechanisms ....................................171
3.1 TypicalAlGaN/GaN2DEGStructures................171
3.2 TraditionalScatteringMechanisms...................172
3.3 NovelScatteringMechanismsinAlGaN/GaN2DEGs...182
4 UsingTheorytoExplainExperimentalData...................194
5 SummaryandConclusions .................................198
6 AppendixontheTheoryofLow-FieldTransport&Mobility .....198
6.1 TheBoltzmannTransportEquation...................199
6.2 Mobility-BasicTheory .............................203
6.3 StatisticsforTwo-andThree-DimensionalCarriers .....206
6.4 ScreeningbyTwo-andThree-DimensionalCarriers.....207
6.5 Mobilityof2DEGs ................................208
6.6 MaterialPropertiesofIII-VNitridesRelevant
toTransport ......................................211
References.....................................................214
LocalPolarizationEffectsinNitrideHeterostructuresandDevices ...... 217
E.T.YuandP.M.Asbeck
1 Introduction..............................................217
1.1 BasicPhysicsofPolarizationEffects .................217
1.2 ExperimentalDeterminationofPolarizationCharge
Densities.........................................219
1.3 ConsequencesforHeterostructures,Defects,andDevices 224
2 Polarization-BasedEngineeringofNitrideHeterostructures......225
2.1 EnhancementofSchottkyBarrierHeightinHFET
Structures........................................229
2.2 Polarization-BasedEnergyBarrierEngineering ........230
2.3 ResidualStressandPiezoelectricEffectsinGaNHFETs.235
2.4 PolarizationEffectsinNitride-BasedHBTsandp-Type
Structures........................................238