Upload
others
View
1
Download
0
Embed Size (px)
Citation preview
M,W,F12:00-12:50(X),2015ECEBProfessorJohnDallesasse
DepartmentofElectricalandComputerEngineering2114MicroandNanotechnologyLaboratory
Tel:(217)333-8416E-mail:[email protected]
OfficeHours:Wednesday13:00–14:00
Today’sDiscussion
• FinishGeneralIntroductiontoSemiconductorElectronics
• LatticesandCrystalStructures• Assignments• TopicsforNextLecture
2
TentativeSchedule[1]
JAN17Courseoverview
JAN19Introtosemiconductorelectronics
JAN22Materialsandcrystalstructures
JAN24Bondingforcesandenergybandsinsolids
JAN26Metals,semiconductors,insulators,electrons,holes
JAN29Intrinsicandextrinsicmaterial
JAN31Distributionfunctionsandcarrierconcentrations
FEB2Distributionfunctionsandcarrierconcentrations
FEB5Temperaturedependence,compensation
FEB7Conductivityandmobility
FEB9Resistance,temperature,impurityconcentration
FEB12InvarianceofFermilevelatequilibrium
FEB14Opticalabsorptionandluminescence
FEB16Generationandrecombination
3 **Subject to Change**
Continued
Current-DensityEquations
• Insemiconductor,inadditiontoanelectroncurrentdensitythereisaholecurrentdensity
• Eachcurrentconsistofthedriftcomponentcausebyfieldandthediffusioncomponentcausedbythecarrierconcentrationgradient
pncond
ppp
nnn
JJJpqDpEqJnqDnEqJ
+=
∇−=∇+=
µµ
Drift Diffusion
5
ContinuityEquations
ppp
nnn
Jq
UGtp
Jq
UGtn
•∇−−=∂∂
•∇+−=∂∂
1
1
For a given volume of semiconductor, the rate change of carrier is the net effect of current flow into the volume and generation and recombination rates within the volume. : electron generation rate : hole generation rate : electron recombination rate : hole recombination rate
nGpGnUpU 6
QuantumMechanics
Heisenberg Uncertainty Principle : Position-Momentum: Δx i Δpx( ) ≥ / 2
Energy-Time: ΔE i Δt( ) ≥ / 2Schrodinger's Equation :
− 2
2m∇2Ψ +VΨ = −
j∂Ψ∂t
(Kinetic Energy + Potential Energy = Total Energy)
Ψ(x, y, z,t) is continuous, finite, and single-valued The derivative in space of Ψ(x, y, z,t) is continuous, finite, and single-valuedThe probability of finding a particle with wave function Ψ is Ψ*Ψ
The particle is somewhere, so Ψ*Ψdxdydz = 1−∞
∞
∫The expectation value of an operator Q is: Q = Ψ*QopΨdxdydz
−∞
∞
∫7
TypesofSolids
http://isic.epfl.ch/page-53777-en.html
SEM: Diamond on Si
http://spie.org/x31901.xml
HRTEM: [110] Si TEM: Glassy Pd
http://www.futurity.org/science-technology
9
CrystalLattice• Lattice:Periodicarrangementofasubstanceor“basis”
– Atom,atomicpair,groupofatoms,molecule,etc.• UnitCell:Containsaregionwhichisrepresentativeofthelattice
whichcanberegularlyrepeatedtorecreatetheentirelattice• PrimitiveCell:Thesmallestunitcellthatcanberepeatedin
integralstepstoproducethelattice– Containsasinglelatticepoint– ThePrimitiveCellisaspecialformoftheUnitCell
• PrimitiveVectors:a,b,c– (1dimension)r=pa– (2dimension)r=pa+qb– (3dimension)r=pa+qb+rc
• BasisVectors:Similartoprimitivevectors,butusedtoreplicatethelatticethroughthetranslationofaunitcell
10
SimpleLatticesandUnitCells
11
Unit Cell
Primitive Cell
Primitive Vectors
Basis Vectors
OtherImportantDefinitions
• LatticeConstant:distancealongtheedgeofacubicunitcell(“a”inexamplesthatfollow)– Moregenerally,thelengthofthebasisvectors
NOTE:Thelatticeconstant,ingeneral,isNOTthedistancebetweenatoms(bondlength).
12
i.e. FCC Unit Cell
CubicCrystalStructures
13
FCCLattice
14
DiamondStructure
15
DiamondStructureBonding
16
DiamondStructureBonding
• TheDiamondStructureisanFCCLatticewithaBasisof2atoms
• TheUnitCellhas4LatticePoints,and8Atoms
17
Basis
Diamond Unit Cell (not primitive cell)
Lattice Constant
WhatDeterminesLatticeSpacing(~)
ImportantMaterialSystems
WurtziteStructure
20
ZincBlendeVersusWurtzite
21
BCCandFCC
PrimitiveCell:BCCandFCC
From: Wolfe, Holonyak, & Stillman, “Physical Properties of Semiconductors
Wigner-SeitzPrimitiveCell
• Drawalinefromagivenlatticepointtoallnearbylatticepoints
• Bisectthelineswithorthogonalplanes• Constructthesmallestpolyhedronthatcontainsthegivenlatticepoint
Assignments
• Readinfopacket–keycoursepoliciesandscheduleareoutlinedhere,includinghourlyexamdates
• HomeworkassignedeveryFriday,duefollowingFriday• BegintoreadChapter1ofStreetman’sbook
– Mon1/22Sections1.1,1.2,1.3.1,1.4– IsuggestreadingallofChapter1,butonlytheabovesectionsareassigned
– Wed1/24:ReviewStreetmanChapter2– Wed1/24:§'s3.1,3.1.1,3.1.2– Fri1/26:§'s3.1.3,3.2.1(HW1Due)– Mon1/29:§'s3.2.3,3.2.4
• Chapter1&2inPierretcoverssimilarmaterial,andcomplementsStreetmanforanotherperspective
26
Outline,1/24/18
• DensityCalculations• MillerIndices• Examples:
– DeterminingMillerindicesforvariouscrystalplanes
– Densitycalculations• EpitaxialGrowthTechnologies
28
InstructionalObjectives(1)BythetimeofexamNo.1(after17lectures),thestudentsshouldbeabletodothefollowing:1.Outlinetheclassificationofsolidsasmetals,semiconductors,andinsulatorsanddistinguishdirectandindirectsemiconductors.2.DeterminerelativemagnitudesoftheeffectivemassofelectronsandholesfromanE(k)diagram.3.Calculatethecarrierconcentrationinintrinsicsemiconductors.4.ApplytheFermi-Diracdistributionfunctiontodeterminetheoccupationofelectronandholestatesinasemiconductor.5.CalculatetheelectronandholeconcentrationsiftheFermilevelisgiven;determinetheFermilevelinasemiconductorifthecarrierconcentrationisgiven.6.Determinethevariationofelectronandholemobilityinasemiconductorwithtemperature,impurityconcentration,andelectricalfield.7.Applytheconceptofcompensationandspacechargeneutralitytocalculatetheelectronandholeconcentrationsincompensatedsemiconductorsamples.8.Determinethecurrentdensityandresistivityfromgivencarrierdensitiesandmobilities.9.Calculatetherecombinationcharacteristicsandexcesscarrierconcentrationsasafunctionoftimeforbothlowlevelandhighlevelinjectionconditionsinasemiconductor.10.Usequasi-Fermilevelstocalculatethenon-equilibriumconcentrationsofelectronsandholesinasemiconductorunderuniformphotoexcitation.11.Calculatethedriftanddiffusioncomponentsofelectronandholecurrents.12.CalculatethediffusioncoefficientsfromgivenvaluesofcarriermobilitythroughtheEinstein’srelationshipanddeterminethebuilt-infieldinanon-uniformlydopedsample.
https://my.ece.illinois.edu/courses/description.asp?ECE340 30
InstructionalObjectives(2)BythetimeofExamNo.2(after32lectures),thestudentsshouldbeabletodoalloftheitemslistedunderA,plusthefollowing:13.Calculatethecontactpotentialofap-njunction.14.Estimatetheactualcarrierconcentrationinthedepletionregionofap-njunctioninequilibrium.15.Calculatethemaximumelectricalfieldinap-njunctioninequilibrium.16.Distinguishbetweenthecurrentconductionmechanismsinforwardandreversebiaseddiodes.17.Calculatetheminorityandmajoritycarriercurrentsinaforwardorreversebiasedp-njunctiondiode.18.Predictthebreakdownvoltageofap+-njunctionanddistinguishwhetheritisduetoavalanchebreakdownorZenertunneling.19.Calculatethechargestoragedelaytimeinswitchingp-njunctiondiodes.20.Calculatethecapacitanceofareversebiasedp-njunctiondiode.21.Calculatethecapacitanceofaforwardbiasedp-njunctiondiode.22.Predictwhetherametal-semiconductorcontactwillbearectifyingcontactoranohmiccontactbasedonthemetalworkfunctionandthesemiconductorelectronaffinityanddoping.23.Calculatetheelectricalfieldandpotentialdropacrosstheneutralregionsofwidebase,forwardbiasedp+-njunctiondiode.24.Calculatethevoltagedropacrossthequasi-neutralbaseofaforwardbiasednarrowbasep+-njunctiondiode.25.Calculatetheexcesscarrierconcentrationsattheboundariesbetweenthespace-chargeregionandtheneutraln-andp-typeregionsofap-njunctionforeitherforwardorreversebias.
https://my.ece.illinois.edu/courses/description.asp?ECE340 31
InstructionalObjectives(3)BythetimeoftheFinalExam,after44classperiods,thestudentsshouldbeabletodoalloftheitemslistedunderAandB,plusthefollowing:26.CalculatetheterminalparametersofaBJTintermsofthematerialpropertiesanddevicestructure.27.Estimatethebasetransportfactor“B”ofaBJTandrank-ordertheinternalcurrentswhichlimitthegainofthetransistor.28.DeterminetherankorderoftheelectricalfieldsinthedifferentregionsofaBJTinforwardactivebias.29.CalculatethethresholdvoltageofanidealMOScapacitor.30.PredicttheC-VcharacteristicsofanMOScapacitor.31.CalculatetheinversionchargeinanMOScapacitorasafunctionofgateanddrainbiasvoltage.32.EstimatethedraincurrentofanMOStransistorabovethresholdforlowdrainvoltage.33.EstimatethedraincurrentofanMOStransistoratpinch-off.34.DistinguishwhetheraMOSFETwithaparticularstructurewilloperateasanenhancementordepletionmodedevice.35.Determinetheshort-circuitcurrentandopen-circuitvoltageforanilluminatedp/njunctionsolarcell.
https://my.ece.illinois.edu/courses/description.asp?ECE340 32
CoursePurpose&Objectives
• Introducekeyconceptsinsemiconductormaterials
• Provideabasicunderstandingofp-njunctions
• Provideabasicunderstandingoflight-emittingdiodesandphotodetectors
• Provideabasicunderstandingoffieldeffecttransistors
• Provideabasicunderstandingofbipolarjunctiontransistors
n-type emitter n-type collector
p-type base
ForwardBias
ReverseBias
electron flow
hole flowleakagecurrent
injectedelectrons
injectedholes
33
TentativeSchedule[2]
FEB19Quasi-Fermilevelsandphotoconductivedevices
FEB21Carrierdiffusion
FEB23Built-infields,diffusionandrecombination
Feb26Review,discussion,problems(2/27exam)
FEB28Steadystatecarrierinjection,diffusionlength
MAR2p-njunctionsinequilibrium&contactpotential
MAR5p-njunctionFermilevelsandspacecharge
MAR7Continuep-njunctionspacecharge
MAR9NOCLASS(EOH)
MAR12p-njunctioncurrentflow
MAR14Carrierinjectionandthediodeequation
MAR16Minorityandmajoritycarriercurrents
3/19-3/23SpringBreakMAR26Reverse-biasbreakdown
MAR28Storedcharge,diffusionandjunctioncapacitance
MAR30Photodiodes,I-Vunderillumination
34 **Subject to Change**
TentativeSchedule[3]
APR2LEDsandDiodeLasers
APR4Metal-semiconductorjunctions
APR6MIS-FETs:Basicoperation,idealMOScapacitor
APR9MOScapacitors:flatband&thresholdvoltage
APR11Review,discussion,problems(4/12exam)
APR13MOScapacitors:C-Vanalysis
APR16MOSFETs:Output&transfercharacteristics
APR18MOSFETs:smallsignalanalysis,amps,inverters
APR20Narrow-basediode
APR23BJTfundamentals
APR25BJTspecifics
APR27BJTnormalmodeoperation
APR30BJTcommonemitteramplifierandcurrentgain
MAY2(LASTLECTURE)Review,discussion,problemsolving
FINALEXAM**Date&timetobeannounced**
35 **Subject to Change**
TentativeSchedule[2]
FEB19Quasi-Fermilevelsandphotoconductivedevices
FEB21Carrierdiffusion
FEB23Built-infields,diffusionandrecombination
Feb26Review,discussion,problems(2/27exam)
FEB28Steadystatecarrierinjection,diffusionlength
MAR2p-njunctionsinequilibrium&contactpotential
MAR5p-njunctionFermilevelsandspacecharge
MAR7Continuep-njunctionspacecharge
MAR9NOCLASS(EOH)
MAR12p-njunctioncurrentflow
MAR14Carrierinjectionandthediodeequation
MAR16Minorityandmajoritycarriercurrents
3/19-3/23SpringBreakMAR26Reverse-biasbreakdown
MAR28Storedcharge,diffusionandjunctioncapacitance
MAR30Photodiodes,I-Vunderillumination
36 **Subject to Change**
ImportantInformation
• CourseWebsite:– http://courses.engr.illinois.edu/ece340/
• DownloadandReviewSyllabus/CourseInformationfromWebsite!• CourseCoordinator:Prof.JohnDallesasse
– [email protected]– Coordinatesschedule,policies,absenceissues,homework,quizzes,
exams,etc.• ContactInformationandOfficeHoursforAllECE340Professors&
TAsinSyllabus• LectureSlides:Clickon“(Sec.X)”nexttomynameininstructorlist• DRESStudents:ContactProf.DallesasseASAP• Textbook:
– “SolidStateElectronicDevices,”Streetman&Banerjee,7thEdition– Supplemental:“SemiconductorDeviceFundamentals,”Pierret– Additionalreferencetextslistedinsyllabus
38
KeyPoints
• AttendClass!– 3unannouncedquizzes,eachworth5%ofyourgrade– Youmusttakethequizinyoursection– Excusedabsencesmustbepre-arrangedwiththecoursedirector– Absencesforillness,etc.needanotefromtheDean
• Seepolicyonabsencesinthesyllabus• NoLateHomework
– Homeworkdueonthedateofanexcusedabsencemustbeturnedinaheadoftime
– Youmustturninhomeworkinyoursection– Noexcusedabsencesforhomeworkassignments– Top10of11homeworkassignmentsusedincalculationofcoursegrade
• Doallofthemtobestpreparefortheexams!• NoCheating
– Penaltiesaresevereandwillbeenforced• TurnOffYourPhone
– Novideorecording,audiorecording,orphotography
39
Homework
• AssignedFriday,DueFollowingFriday– Duedatesshowninsyllabus
• DueatStartofClass• FollowGuidelinesinSyllabus• PeerDiscussionsRelatedtoHomeworkareAcceptableandEncouraged
• DirectlyCopyingSomeoneElse’sHomeworkisNotAcceptable– Gradershavebeeninstructedtowatchforevidenceofplagiarism
– Bothpartieswillreceivea“0”ontheproblemorassignment
40
Absences
• Theabsencepolicyinthesyllabuswillbestrictlyenforced• Toreceiveanexcusedabsence(quiz),youmust:
– Pre-arrangetheabsencewiththecoursedirector(validreasonandproofrequired)
– CompleteanExcusedAbsenceFormattheUndergraduateCollegeOffice,Room207EngineeringHall(333-0050)
• Theformmustbesignedbyaphysician,medicalofficial,ortheEmergencyDean(OfficeoftheDeanofStudents)
• TheDean’sOfficehasrecentlyputastrictpolicyinplace(3documenteddaysofillness)– Excusedquizscorewillbeproratedbaseduponaverageofcompletedscores– Noexcusedabsencesaregivenforhomework,butonlythebest10of11are
usedtocalculateyourfinalgrade– Excusedabsencesarenotgivenforexams,exceptinaccordancewiththe
UIUCStudentCode– Unexcusedworkwillreceivea“0”
• Failuretotakethefinalwillresultinan“incomplete”grade(ifexcused)ora“0”(ifunexcused)
41
Exams
• ExamI:TuesdayFebruary27th,7:30-8:30pm• ExamII:ThursdayApril12th,7:30-8:30pm• FinalExam:Date/TimeToBeAnnounced
– DeterminedbyUniversityF&S
42
Grading
GradingCriterion
Homework 10%
Quizzes 15%
HourExamI 20%
HourExamII 20%
FinalExam 35%
Total 100%
HistoricalGradeTrends*
Spring2016
Fall2016
Spring2017
A’s 27% 28% 27%
B’s 37% 26% 38%
C’s 27% 25% 27%
D’s 6% 16% 4%
F’s 3% 5% 4%
*Past performance is not necessarily indicative of future results
43
MyRecommendations
• Readthesyllabusandinformationpostedonthecoursewebsite
• Attendclass&participate• Attendofficehours(TAandProfessors)• Readthebook• Re-readthebook• Lookatandreadselectedportionsofthesupplemental
texts• Formstudygroupstoreviewconceptsanddiscusshigh-
levelapproachesforsolvinghomeworkproblems– Don’tformstudygroupstocopyhomeworksolutions
• Don’tmissanyhomework,quizzes,orexams• It’shardtoovercomeazero
• Askquestionsinclass!44