M,W,F12:00-12:50(X),2015ECEBProfessorJohnDallesasse

DepartmentofElectricalandComputerEngineering2114MicroandNanotechnologyLaboratory

Tel:(217)333-8416E-mail:jdallesa@illinois.edu

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

–  jdallesa@illinois.edu–  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

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MyRecommendations

•  Readthesyllabusandinformationpostedonthecoursewebsite

•  Attendclass&participate•  Attendofficehours(TAandProfessors)•  Readthebook•  Re-readthebook•  Lookatandreadselectedportionsofthesupplemental

texts•  Formstudygroupstoreviewconceptsanddiscusshigh-

levelapproachesforsolvinghomeworkproblems–  Don’tformstudygroupstocopyhomeworksolutions

•  Don’tmissanyhomework,quizzes,orexams•  It’shardtoovercomeazero

•  Askquestionsinclass!44