Negative Differential Resistance and Instabilities in 2D ...serge/113.pdf · Negative Differential...
31
-- -- Semiconductors 2D in Instabilities and Resistance Differential Negative Vickers J. A. and Ridley, K. B. Balkan, N. by ed. [Physics] Series ASI NATO 307 B 1993) York (New Press Plenum 53-82, pp. , TRANSFER SPACE REAL ON BASED DEVICES LOGIC EMITTING LIGHT HETEROSTRUCTURES InGaAs/InAlAs COMPLEMENTARY IN Mastrapasqua Marco and Luryi Serge Laboratories Bell AT&T 07974 NJ Hill, Murray ABSTRACT devices logic light-emitting novel of implementation the and principle the discuss We conducting complementary between electrons hot of (RST) transfer real-space the on based doped is emitter, the layers, these of One layers. n for contacts more or two has and -type a into injected are electrons field, this by Heated field. electric lateral the applying complementary p is current injection The independently. contacted layer, collector -type transferred the of recombination the from arising signal luminescence a by accompanied region. active collector designed specially a in electrons functional implement to one enables RST by injection charge of symmetry peculiar The the in gate OR exclusive an as acts contacts emitter two with structure simplest The gates. logic The voltages. input the on light output the and current collector the both of dependence electrically is and NAND and OR as functions such performs device multiterminal at demonstrated are operations logic powerful These functions. these between reprogrammable temperature. room transistors. RST of properties symmetry the of studies theoretical recent review also We variety a reveal simulation, device transient and modeling continuation on based studies, These of novelty striking a and instabilities of multiply-connected RST A characteristics. current-voltage the in occurs injection hot-electron which in states steady anomalous support can transistor reflection the break states these of Some electrodes. emitter the between voltage any of absence electron the states, anomalous the In midpoint. at channel the to normal plane the in symmetry hot-electron of formation The electrode. collector the from field fringing a to due is heating state. collector-controlled a such to transition a represents transfer real-space in domains INTRODUCTION 1. new of development the is research microelectronics the in direction important An devices functional an require normally would that tasks logic perform can which , offers (CHINT) transistor injection charge The transistors. several of assembly context. this in opportunities interesting 1 devices of class a to refers concept CHINT The principle the on based 2,3 between electrons hot of (RST) transfer real-space of this employing devices functional Several layers. conducting contacted independently literature. the in discussed been have principle 4-8 conducting the of One 1a. Fig. in illustrated is structure CHINT generic The voltage heating the with cathode, hot-electron a of role the plays emitter, the layers, contacts the to applied S and D separated is collector, the layer, conducting other The . the of increase the in itself manifests effect RST The barrier. heterostructure a by current collector I C bias collector positive constant a at V C high sufficiently a when , bias heating V DS applied. is is discussion, present our for essential transistors, RST of property fundamental A the equivalence symmetry 9,10 states internal the between S [V D , V C] at device the of configurations: bias external different S [ V D , V C ] → ← S [ - V D ( , V C - V D ] ) . (1)
Transcript of Negative Differential Resistance and Instabilities in 2D ...serge/113.pdf · Negative Differential...
----Semiconductors2DinInstabilitiesandResistanceDifferentialNegative
VickersJ.A.andRidley,K.B.Balkan,N.byed.[Physics]SeriesASINATO 307B 1993)York(NewPressPlenum53-82,pp.,
TRANSFERSPACEREALONBASEDDEVICESLOGICEMITTINGLIGHTHETEROSTRUCTURESInGaAs/InAlAsCOMPLEMENTARYIN
MastrapasquaMarcoandLuryiSerge
LaboratoriesBellAT&T07974NJHill,Murray
ABSTRACT
deviceslogiclight-emittingnovelofimplementationtheandprinciplethediscussWeconductingcomplementarybetweenelectronshotof(RST)transferreal-spacetheonbased
dopedisemitter,thelayers,theseofOnelayers. n forcontactsmoreortwohasand-typeaintoinjectedareelectronsfield,thisbyHeatedfield.electriclateraltheapplying
complementary p iscurrentinjectionTheindependently.contactedlayer,collector-typetransferredtheofrecombinationthefromarisingsignalluminescenceabyaccompanied
region.activecollectordesignedspeciallyainelectronsfunctionalimplementtooneenablesRSTbyinjectionchargeofsymmetrypeculiarThe
theingateORexclusiveanasactscontactsemittertwowithstructuresimplestThegates.logicThevoltages.inputtheonlightoutputtheandcurrentcollectorthebothofdependence
electricallyisandNANDandORasfunctionssuchperformsdevicemultiterminalatdemonstratedareoperationslogicpowerfulThesefunctions.thesebetweenreprogrammable
temperature.roomtransistors.RSTofpropertiessymmetrytheofstudiestheoreticalrecentreviewalsoWe
varietyarevealsimulation,devicetransientandmodelingcontinuationonbasedstudies,Theseofnoveltystrikingaandinstabilitiesof multiply-connected RSTAcharacteristics.current-voltage
theinoccursinjectionhot-electronwhichinstatessteadyanomaloussupportcantransistorreflectionthebreakstatestheseofSomeelectrodes.emitterthebetweenvoltageanyofabsence
electronthestates,anomaloustheInmidpoint.atchannelthetonormalplanetheinsymmetryhot-electronofformationTheelectrode.collectorthefromfieldfringingatodueisheating
state.collector-controlledasuchtotransitionarepresentstransferreal-spaceindomains
INTRODUCTION1.
newofdevelopmenttheisresearchmicroelectronicstheindirectionimportantAndevicesfunctional anrequirenormallywouldthattaskslogicperformcanwhich,
offers(CHINT)transistorinjectionchargeThetransistors.severalofassemblycontext.thisinopportunitiesinteresting 1 devicesofclassatorefersconceptCHINTThe
principletheonbased 2,3 betweenelectronshotof(RST)transferreal-spaceofthisemployingdevicesfunctionalSeverallayers.conductingcontactedindependently
literature.theindiscussedbeenhaveprinciple 4−8
conductingtheofOne1a.Fig.inillustratedisstructureCHINTgenericThevoltageheatingthewithcathode,hot-electronaofroletheplaysemitter,thelayers,
contactsthetoapplied S and D separatediscollector,thelayer,conductingotherThe.theofincreasetheinitselfmanifestseffectRSTThebarrier.heterostructureaby
currentcollector I C biascollectorpositiveconstantaat V C highsufficientlyawhen,biasheating V DS applied.is
isdiscussion,presentourforessentialtransistors,RSTofpropertyfundamentalAthe equivalencesymmetry 9,10 statesinternalthebetween S [V D , V C] atdevicetheof
configurations:biasexternaldifferent
S [ V D , V C ] →← S [ − V D (, V C − V D ]) . (1)
----
thetonormalplanetheinsymmetryreflectionthefromfollowscorrespondenceThissimilaraAlthoughmiddle.theinchannelthecutswhichdirectionsource-drain
statesinternalbetweenexistsrelation S [ V D , V G ] anistheretransistor,field-effectaintheandterminaloutputtheiscollectorCHINTthethatindifferenceimportantanunderinvariantiscurrentoutputthethatimplies(1)Eq.byexpressedsymmetry
voltagesinputtheofinterchange V S and V D exclusive-ORanexhibitsdevicetheThus.(xor logicbinaryasregardedvoltages,inputtheoncurrentcollectortheofdependence)signals.
threewithdeviceRSTainobtainedisfunctionalitylogicpowerfulmoreEventerminals.input 6 cyclicahasgate,ORNANDtheastorefershallwewhichdevice,This
tocorresponds1c)(Fig.tabletruthIts1b.Fig.symmetry,3-fold ornand (Vj)= or (V1, V2) when V3 andlow,is ornand (Vj) = nand (V1, V2) when V3 high.is
V2
V3
V1
(b)
I C 1 1 1 01 0 1 1
V2 1 0 0 11 0 0 1
V1 0 0 1 10 0 1 1
V3 0 1
output
or nandfunction
logic
input
(c)
(a)
BARRIER
S D
C
COLLECTOR
EMITTER1Fig. principletransistorinjectionCharge:
logic.RSTtheandCHINT.aofdiagramSchematic(a)
fieldthebyheatedelectrons,Emitterelectrodesbetweenapplied S andand D ,
aslayer,collectortheintoRSTundergoarrow.thebyindicated
terminalsInputgate.logicORNAND(b)symmetrycyclic3-foldawitharranged3-1.and2-3,1-2,channelsthreedefine
oftableTruth(c) I C (V1, V2, V3 RSTThe).iscurrent ffo whenstatestwoin
V1 = V2 = V3 and on sixothertheineverysymmetry,Bystates. on hasstate
samethe I C.
logicinjectionchargeofinventionThe 6 symmetrytheonattentionfocusedhastheonbasedbetolikelyareapplicationspotentialTheirtransistors.RSTofproperties
symmetrysameThepolarity.fieldheatingthetorespectwithsymmetrypeculiartheofanalysistheinupshows instabilities andinjectionhot-electronthewithassociated
discoveryrecentunexpectedAntransistors.RSTinformationdomainthe 9 theisatstatesanomalousofnumberaofexistence V D = 0 onlynotarewhichofsome,
alsobutstationary stable thestates,theseInperturbations.smalltorespectwiththeofBecauseelectrode.collectorthefromfieldfringingthetodueisheatingelectron
atstates(1),relation V D = 0 theinreflectionstorespectwithsymmetricbeeithermusttheoreticalBypartners.broken-symmetrypossessorchanneltonormalmidplane
foundbeenhasitoperationCHINTtheofmodeling 9 possessesdevicethethatcomplicatedintrinsically – multiply-connectedoften – IV ofApplicationcharacteristics.highsufficientlya V D fixedaat V C > 0 thebyaccompaniedtransition,switchingaforces
finitethewhenformdomainsthePhysically,domain.electronhotaofformationatoelectronsofratesupply " spothot " Thespot.thatfromfluxRSTthebyexceededis
(fieldfringingtheunscreendomainsdepleted "normally" electrons)channelbyscreenedcontrolled.collectorbecomesRSTtheand
involveddeviceslogicrelatedandCHINTonworktheofallrecently,Untilthewithheterostructures conductivityoftypesame theandchannelemitterthebothin
reviewThecollector. 10 real-spaceunipolaronreferencesgeneralofnumberacitesdiscussedusofoneRecently,transistors.transfer 11 ofRSTtheusingofpossibilitythe
aintocarriers complementary devicesemittinglightimplementtolayercollectorprogressSignificantinput.electricaltorespectwithfunctionalitylogicawithendowed
firstTheyear.lasttheduringlaboratoriesourinmadebeenhasprogramthisinandheterostructureInGaAs/InAlAsainimplementedwasCHINTcomplementary
----
thedemonstrated xor operation.12,13 wasgateORNANDmultiterminaltheSubsequently,implemented,14 thedemonstrating or and nand functions – andlightoutputtheinboth
currentcollectorthe – functions.thesebetweenswitchingelectricaltheaswellascontributions.recentthereviewsworkpresentThe 12− 9,14 structuresepitaxialThe
Electricalsection.nexttheindiscussedaresequencefabricationtheandusedtheir3,Sect.indescribedarestructuresCHINTcomplementarytheofcharacterization
theofResults5.Sect.inoperationlogictheand4,Sect.incharacterizationopticalsimulationnumerical 9 1a)(Fig.structureCHINTsimplesttheintransporthot-electronof
7.Sect.insummarizedareconclusionsOur6.Sect.inreviewedare
STRUCTURES2.
discussedstructuresdevicelogictheofcross-sectionsschematicshow2Figures2b.Fig.ingateORNANDand2aFig.inillustratedisgateXORtheofStructurebelow.
The In0.53Ga0.47As/In0.52Al0.48As beammolecularbygrownbeenhaveheterostructuresusedfirstscheme,contactepitaxialtheonbasedisdesignThesubstrate.InPonepitaxy
al.etMenszbyCHINToffabricationthein 15 islengthchannelthescheme,thisIntheinetchedtrenchabydefined n + (layercap a theofportionsremainingthewhile),
Themetal.drainandsourcethetocontactsohmicmakelayercap A25 ˚ (layerInAlAs b )layercaptheofetchingselectivetheinstopetchanasusedis 16 includingpatterns,All
lithography.contactopticalstandardbydefinedweretrenches,the1b,Fig.ofarrangementelectrodetriangulartheofinsteadgate,ORNANDtheIn
electrodesfourwithobtainedissymmetrycyclicrequiredthe 3,3,2,1 ˜ – which,oftwo3and3 ˜ (identicallogicallybeing, V 3 ≡ V3 split.physicallythough)
S D
C
L ch
adc
b
InGaAs channel
InAlAs barrier (undoped)
InGaAs collector active region
InAlAs collector confinement layer
n (Si: 1017
p (Be: 3x10 18 )
p (Be: 10 17 )
)
InP semi-insulating substrate
500 A
2000 A
500 A
1 mµ
e
o
o
o
a: 200 A InGaAs,
b: 25 A InAlAs,
c: 2500 A Si N3 4
o
o
on (Sn: 1020 )
n (Sn: 1019 )
d: 300 A Ti / 1800 A Au
e: 800 A AuBe / 2000 A Auo
o
o o
2
C
ad
c
InGaAs emitter
InP substrate
e
1 mµ
1000 Ao
InAlAs barrier (undoped)
InGaAs collector active region
400 Ao
1500 Ao
2000 Ao
313~
f
L ch
(Zn: 5x10 18 )
a: 200 A InGaAs,
b: 25 A InAlAs,
c: 15 A InGaAs (undoped)
o
o
on (Sn: 1020 )
n (Sn: 1019 )
d: 300 A Ti / 1800 A Au
e: 800 A AuBe / 2000 A Au
f: 1500 A Si No
o
o o
o
3 4
b(Si: 3x10 17 )
(Be: 3x10 17 )
InAlAs collector confinement layer (Be: 1018)
InAlAs collector contact layer (Be: 1019)
2aFig. firsttheofsectionCross:injectionchargecomplementary
transistor.12,13 channelemitterTheinetchedtrenchthebydefinedlength,
layercapthe (a ) is, L CH = 3 µ theandmwidth W = 50 µm.
2bFig. gate.ORNANDThe: 14 ofEachtrenchesbydefinedchannels,threethe
layercapthein (a ) lengthhas,L CH = 1 µ widthandm W = 40 µm.
thefromresultssymmetryCyclicconditionboundaryperiodic V 3 ≡ V3 .
therebutsimilar,generallyare2band2aFigs.inshownstructures,epitaxialTheaongrownisstructureORNANDThedifferences.noteworthyseveralare p -typeparasiticthereducetolayercontactcollectordopedheavilymoreausesandsubstrate
dopedheavilymorealsoischannelemitterThecircuit.collectortheinresistanceseriesaensureandpotentialsurfacethebydepletioncompleteitsavoidto "normally-on"
positiveaofabsencetheinevenconductswhichchannel, V C.
----
ain2a)(Fig.deviceXORtheofdiagramenergy-bandschematicashows3FigurestructureORNANDthefordiagramscorrespondingThetrench.theundercross-sectiondepletednotischannelemitterthethatbeingdifferencemainthesimilar,quiteare
("normally-on" indeviceXORourIndoping.heaviertodueequilibrium,in)theandpotentialsurfacethebydepletedentirelyischannelthe3a,Fig.equilibrium, pn
ainducetovoltagecollectorpositivearequiresconductionchannelthethatsojunction,theInbarrier.thewithinterfacetheatgaselectrontwo-dimensional "flat-band"
biascollectorthe3b,Fig.inillustratedcondition, V C = V FB ∼∼ 0.6 thetocorrespondseVbetweendifferencework-function n andchannelthein-InGaAs p thein-InGaAs
the3c,Fig.regime,operatingtheIncollector. pn theandbiasedforwardisjunctionthewithinterfacestwotheatdiscontinuitiesbandthetodueiscurrenttoobstaclemain
InGaAs/InAlAstheindiscontinuitybandvalencetheasInasmuchbarrier.InAlAsdiscontinuitybandconductionthethansmallerisheterosystem 17 ( ∆E V = 0.20 eV
< ∆E C = 0.50 bewillcurrentcollectortheRST,ofabsencetheinthat,expectcanweeV)holes.bydominated
EC
EVEF
(a)
VFB
(b)
VC hν
(c)
RST
3Fig. indiagramenergy-bandSchematic:theoftrenchtheundercross-sectiona
2a.Fig.ofCHINTcomplementarytheandcollectorTheEquilibrium.(a)
aformlayersemitter-channel pn junction,Thebarrier.wide-gapabyseparated
surfacethebydepletedischannelpotential.
flat-bandThecondition.Flat-band(b)voltage V C = V FB becauseundeterminedis
potential.surfacetheinuncertaintyanofcross-ainvoltageflat-bandcalculatedThe
iscontactstheundersection V FB = V.0.63chargechannelTheregime.Operating(c)
theWhenfield.collectorthebyinducedisthealongappliedisfieldelectricheating
hot-electronabecomeslatterthechannel,electronstransferredReal-spaceemitter.
theinholeswithrecombineradiativelycollector.theofregionactive
biasdrain-to-sourceabygeneratedisheatingElectron V DS transferreal-spaceThe.currentcollectorincreasingtheinitselfmanifests I C abyaccompaniedisitusual,As.currentdraintheinresistancedifferentialnegative I D structures,complementaryourIn.
abyaccompaniedisinjectionRSTthe 1.6 µ thefromarisingsignal,luminescencemregion.activecollectorInGaAstheinholeswithelectronsinjectedtheofrecombinationconfinespatiallytoiscollectortheinlayerInAlAswide-gaptheofpurposeThe
low-resistanceaprovidetotime,sametheatand,barriertheoverinjectedelectronsisConfinementimportant.veryarerequirementsBothcurrent.collectortheforpath
wouldelectronsinjectedtheofmost(otherwiseefficiencyradiativethefornecessaryisresistancecollectorlowandrecombination)topriorcontactcollectorthereach
severelyotherwisewouldwhicheffect,back-gatingspuriousaminimizetonecessaryleveldopingtheIfcurrent.RSTavailablethelimit N A isbarrierconfiningthein
resistancelowaofrequirementsthebetweenstruckbemustbalanceathenuniform,higherby(minimized N A thebetweeninterfacetheatvelocityrecombinationlowaand)
lowerby(minimizedlayersconfinementandactive N A well-knownsolution,betterA).confinementtheofmostdopeheavilytoislasers,heterostructuredesigningofartthein
Thisregion.activetheadjacentimmediatelysublayerlow-dopedthinaleavebutlayerrecentmoreourofdesigntheinoptimized)meansnoby(thoughusedwasapproach
2b.Fig.structure,
----
CharacterizationElectrical3.
ofthosefromdifferentquiteareCHINTcomplementaryaofpropertiesElectricaldevices.unipolar 4,10 andcollectorthethatfacttheinrootedaredifferencestheofMost
aformemitterthe pn deviceThebetween.inbarrierwide-gapawithjunctiontheofbiasforwardatocorrespondsregimeoperating pn relymustwehencejunction,
Incurrent.leakageunwelcometheblocktodiscontinuitiesband-gaptheonexclusivelywhichcurrentcollectortheofpartthatleakagetheastorefershallwefollowswhat
temperatureelectrontheofindependentlyflows T e theinfieldlateralthebycontrolledtheofpartimportantanismechanismleakagetheofIdentificationchannel.emitter
characterization.device
CurrentLeakage3.1
achoosingbysuppressedstronglybecanleakagethetransistor,RSTunipolaraInbeenhaveresultsExcellentdiscontinuity.bandconductionlargeawithheterostructure
obtained16 haswhichsystemInGaAs/InAlAsthein ∆E C = 0.50 complementaryaIneV.emittertheintocollectorthefromholesoffluxtheaboutworrytohaveweCHINT,
channel.2Fig.theofcharacteristicscurrentleakagecollectortheshow5aand4Figures
ofvaluesmeasuredThegrounded.contactsemitterallwithdevices I C plottedarebiascollectortheagainst V C temperatures,highAttemperatures.differentfor
T >∼ 200 modelthermionictheobeyscurrentthebiaslowrelativelyandK,
I C = I CSAT e
qVC⁄ kTn , (2a)
I CSAT = AS ∗T 2 e Φ⁄− kT , (2b)
where n factor,idealitydiodetheis I CSAT current,saturationthe S emittertotaltheis
contacts,includingarea Φ holethebetween(separationbiaszeroatheightbarriertheischanneltheatbarriertheinedgebandvalencetheandcollectortheinlevelFermi
andinterface), A∗ theofslopestheFromconstant.Richardsoneffectivethe I C (V C)determinewe5aand4Figs.inlinesdashedthebyindicatedbias,lowatcurves n ∼∼ 1.4 .
toExtrapolating V C = 0 determinewe, I CSAT thetofittedbeindeedcanitthatfindand
(2b).formofplotsArrheniustheshow5bFig.and4Fig.toinsetThe I C
SAT ⁄T 2 versus T − 1 ingiveplotstheseofslopesTherange.high-temperaturethe =Φ 0.90 indevicetheforeV
and2aFig. =Φ 0.84 reasonableinarevaluesThese2b.Fig.device,ORNANDtheforeVvaluescalculatedwithagreement Φh theirtorelativeholesforheightbarriertheof
gapsenergyroom-temperaturetheonbasedcollector,theinlevelFermiE G
In0.53
Ga0.47
As= 0.75 eV, E G
In0.52
Al0.48
As= 1.45 discontinuitiesbandtheeV, ∆ E C = 0.50 eV,
∆ E V = 0.20 2aFigs.indevicestheforvaluescalculatedThelevels.dopinggivenandeV,respectively,are,2band Φh = 0.89 andeV Φh = 0.92 thewithcontrastedbetoisThiseV.
electrons,emitterforheightsbarrierzero-biasestimated Φe = 1.10 andeV Φe = 1.13 eV,ofvaluescalculatedandmeasuredthebetweendiscrepancyslightTherespectively. Φh
dopingactualtheofdeviationminorabyexplainedbemaydevicemultiterminaltheineffects.tunnelingthermally-assistedbyperhapsornominalfromlevels
conditionflat-bandtheexceedingbiases,collectorhigherAt V C > V FB oftopthe,aofregimeoperatingtheisThisinterface.collectortheatisholesforbarrierthe
withcurrentcollectortheofincreaseFurtherCHINT.complementary V C occursalso,andlevel)Fermithe(increasingholesofaccumulationtheofbecauseprimarily
barrier.effectivethelowerswhichtunnelingholeofroleincreasingtheofbecausewhen(2)Eq.fromdepartscurveleakagetheHence V C > V FB fromevidentisAs.
ofslopetheregimeoperatingthein5a,and4Figs. log I C (V C) Atgentle.relativelyistemperatures,low T <∼ 150 dominanttheisholesoftunnelingassistedthermallyK,
mechanism.leakage
----
|0
|1
|2
|3
||
||
|
| | | |
||
||
|
235K
290K
200K150K
100K
10-20
10-16
10-12
10-8
10-4
Collector Bias VC, V
Col
lect
or L
eaka
ge C
urre
nt I C
, A
|35
|45
|55
|65
||
|| | | | |
||
||
1/kT, eV-1
10-28
10-24
10-20I C
SA
T/T
2
4Fig. ofcharacteristicsdiodeCollector:temperatures.differentatdevice2aFig.the
togetherconnectedaredrainandSourcetheindicatelinesDashedgrounded.and
ofextrapolationlinear I C forwardzerotolinesdashedtheofinterceptsThebias.
defineaxisordinatethewith I CSAT Inset.
ofplotArrheniusanshows I CSAT ⁄T 2 The.
energyactivationmeasured =Φ eV0.90withagrees Φh = takingcalculatedeV,0.89
E Fe = andmeV12 E F
h = theformeV105fromseparationslevelFermiequilibriumlayeremittertheinbandconductionthefromandcontactssource/draintheunder
activecollectortheinbandvalencetherespectively.layer,
|0
|1
|2
|3
|4
||
||
||
||
| | | | |
||
||
||
||(a)330 K
265 K
300 K
77 K
6 K
Reverse, 300 K
Reverse, 6 K
10-16
10-14
10-12
10-10
10-8
10-6
10-4
10-2
Collector Bias VC [V]
Col
lect
or L
eaka
ge C
urre
nt I C
[A]
|30
|35
|40
|45
|
| | | |
|
(b)
slope 0.84 eV
1/kT, eV-1
I CS
AT/T
2
10-20
10-19
10-18
10-17
5Fig. severalat2b)(Fig.deviceORNANDtheofcharacteristicscurrentleakageCollector:Curvestemperatures. I C (V C grounded.electrodesemitterfourallwithmeasuredwere)collector-emitterForward-biased pn tocorrespondsjunction V C > undercurrentleakageThe.0
representcurvesplottedtheandpolarityoppositeofisbiasreverse I C (a)inlinesDashed.logofextrapolationlinearaindicate I C theof(b)plotArrheniustheFrombias.forwardzeroto
valueextrapolated I CSAT ⁄T 2 relativeheightbarriercalculatedTheeV.0.84isenergyactivationthe
islevelFermiholetheto Φh = assumingeV,0.92 E Fe −= and(degenerate)meV21 E F
h = meV82levels.dopinggiventhefromestimated
CharacteristicsTransistor3.2
injectionchargeaofcharacteristicscurrent-voltagepresentingofwayusualTheoffamilytheplottoistransistor I C (V D) and I D (V D) ofvaluesconstantatcurves V C.
atCHINTcomplementarytheofcharacteristicssuchshow6(a)-(c)Figures T = 290 K,T = 235 andK, T = 100 lowTheK. V D ainthattosimilarischaracteristicstheofpart"normally-off" gate.aofroletheplayingcollectorthewith(FET),transistorfield-effect
fixedaAt V C voltageheatingtheincreasingand V D (firstcurrentchannelthe, V D <∼ 0.5 V)valuesaturationThesaturation.fortendencyawithsublinearlythenlinearly,increases
withincreasescurrenttheof V C highisvoltageheatingtheWhenFET.ainwoulditas,differentialnegativeashowscurrentdraintheRST,significantaestablishtoenough
itwheretemperatures,loweratenhancediseffectNDRThe(NDR).resistanceindropabruptanbyitselfmanifests I D rapidlycurrentcollectortheSimultaneously,.
value.leakageitsfromincreases
----
3.0V 1.06 2.5V 1.02 2.0V < 1
|0.0
|0.5
|1.0
|1.5
|2.0
|0.0
|2.5
|5.0
|7.5
|10.0 | | | | |
||
||
|
(a)T = 290 K
0.0
1.0
2.0
3.0
4.0
Drain Bias VD, V
Dra
in C
urre
nt I D
, mA
VC IC on/off
Col
lect
or C
urre
nt I C
, mA
3.0V 1.5 2.5V 1.5 2.0V 1.2
|0.0
|0.5
|1.0
|1.5
|2.0
|0
|2
|4
|6
|8
|10
| | | | |
||
||
||(b)T = 235 K
0.0
0.4
0.8
1.2
1.6
Drain Bias VD, V
Dra
in C
urre
nt I D
, mA
VC IC on/off
Col
lect
or C
urre
nt I C
, mA
|0.0
|0.5
|1.0
|1.5
|2.0
|0
|5
|10
|15
| | | | |
||
||(c)T = 100 K
0.0
0.5
1.0
1.5
3.5V 1.0x103
3.0V 1.3x104
2.5V 4.9x104
2.0V 2.8x104
Drain Bias VD, V
Dra
in C
urre
nt I D
, mA
VC IC on/off
Col
lect
or C
urre
nt I C
, mA
6Fig. atcharacteristicsCurrent-voltage:biasescollectorandtemperaturesdifferent
V C currentDrain. I D thebyshowniscurrentcollectorandlinesdashed I C theby
theshowlinesdottedThelines.solidofbehaviorleakageexpected I C thein
The4.Fig.fromcalculatedRST,ofabsencecalculatedisratioon/offcurrentcollector
valuemaximum(relative)thedividingbyof I C thebeforevalueminimumitsby
transfer.real-spaceofonset(a) T = (b)K;290 T = (c)K;235 T = K.100
inincreasethethatNote I C diminishingforcompensatefullynotdoes I D which,becanbehaviorThisdecreases.alsocurrentsourcethethatlaw,Kirchhoff’sbymeans,
field.collectortheofeffectbackgatingthetoduebothmechanisms,twobyexplaineddynamicallychargethetodueisintrinsic,termedbemightwhichmechanism,firstThe
collector.thetowardtransitinlayerbarriertheinstored 4 chargedynamicnegativeTheemittertheinconcentrationelectronthereducesandfieldcollectorthescreenspartiallycurrentcollectortheoffeedbacknegativeatodueismechanismsecondThechannel.
RSTtheWhenpath.collectortheinresistanceseriesparasiticaofpresencetheincollectorthereducesresistanceseriesthatondropvoltagetheflow,tobeginscurrent
theloweringeffectivelypotential, V C sourcethedecreasinginresulteffectsBoth.mayresistanceseriesthealloyed,properlynotiscontactcollectortheWhencurrent.
theofmostforaccountmayeffectspace-chargedynamicthedeviceourIndominate.†estimates.simplebyascertainedbecanascurrent,sourcetheindecrease 4 Nevertheless,
(resistanceseriescollectorresiduala R C <∼ k0.5 Ω at 290 lowerathigherbutKwithoutstructure;ourinpresentbetolikelyisbelow)seetemperatures, R C itfindwe
highatcharacteristicstheinfeaturescertainunderstandtohard V D higherstilland V C.maximumwell-definedashowscurrentcollectorthe6,Figs.fromseenasIndeed,
offunctionaas V D electroluminescencethebytrackedfaithfullyisbehaviorThis.awithassociatedismaximumthethatindicates4,Sect.indiscussedaswhich,signal,
highatcurrentRSTelectrontheofdecrease V D aofexistencethethatbelieve,We.ofdecreasetheandcurrentcollectortheinpeak I C higherat V D thetorelatedis
theofpotentialtheinincrease " spothot " wherechanneltheinregionhigh-fieldthe(i.e.
________________
Thiscurrent.RSTlittlerelativelyaaccompanyingNDRgiantashowusuallystructuresSuch†contact.alloyedtheannealinguponawaygoesanomaly
----
atbarriertheinfieldtheofReversalcollector.thetorelativeoccurs)RSTtheofmostinpeakNoRST.thesuppressesexponentiallyspothotthe I C whenobservedis V D is
increased simultaneously tocorrespondswhichvoltage,collectortheincreasingwithfixedatvoltagesourcethevarying V D and V C naturallyspothottheatreversalField.
lowerat6Fig.indataourexplains V C ≤ 2.5 6cFig.ofexaminationcloseaHowever,V.ofvalueshigherfordirectlyworknotdoesitthatshows V C forThus,. V C = 3.5 V the,
nearoccursmaximum V D = 1.7 wouldthisresistance,collectoraofabsencetheInV.reversalfieldnoandregimeoperatingtheinischannelemitterentirethethatsuggest
seriesaassumetosufficientisitmeet,endsthemakeTospot.hottheatplacetakesresistance R C ∼∼ k1 Ω temperatures.lowatcircuitcollectorthein
thedisentangletonecessaryalsoisresistancesseriesparasitictheofConsiderationradiativeinternaltheestimatingforimportantiswhichleakage,carriercoldfromRST
higher-temperaturetheIn4).Sect.(seetemperatureshigheratespeciallyefficiency,theofonsetthetopriordecreasetoseeniscurrentcollectorthe6b,and6aFig.plots,
collector-to-draindecreasingwithcurrentleakagediminishingthetodueisThisRST.the6cFig.ofscaletheonbuttemperatures,lowatoccursbehaviorsameThebias.
ittemperatures,higheratcurrentRSTtheestimatetoorderInresolved.notisleakagecurrent.collectormeasuredthefromcontributionleakagethesubtracttonecessaryis
thatfromleakagethebands,flatnearisregiondraintheinjunctionthewhenIdeally,factorabyroughlydiminishmustleakageoveralltheandoffshuteffectivelyisregion
somewhatresistancesparasitictheofinclusionbelow,discussedasHowever,2.ofanalysis.thecomplicates
current:collectorthetocontributionstwobetweendistinguishtolikewouldWe
I C = I CLKG + I C
RST , (3)
where I CRST andelectronshotofcurrenttransferreal-spacetheis I C
LKG collectortheisconfigurationvoltagegivenaatflowwouldwhichcurrenttheasdefinedleakage,
( V C , V D Bothabsent.werephenomenonheatingelectrontheif) I CLKG and I C
RST dependvoltagestheon V C and V D usewecomponent,leakagetheofbehaviortheestimateTo.
therepresentssymbolFETThe7a.Fig.inshowncircuit,equivalentapproximatean"intrinsic" thetoareathisofcontributiontrench;theunderdevicetheofportion
thetocorrespondsymbolsdiodeThenegligible.assumediscurrentleakage pnourthatherenotedbeshould(itareascontactdrainandsourcetheinjunctions "diode"
conventionalanotis pn theseparatingbarrierheterostructureahasbutjunction, p andthe n TheRST.theneglectweleakage,thecalculatingofpurposetheForregions).resistors R S , R D and, R C anddrain,source,theinresistancesseriesparasiticrepresent
respectively.collector,abyparameterscircuitequivalentthedeterminetoablebetonicebewouldIt
theillustrates7bFigurepurpose.thatforinsufficientaredataourbutfit,squareleasttherepresentslinesolidThesituation. I C (V D) atcurve V C = 2.5 andV T = 235 areWeK.
atcurrentRSTtheofpeakthenearcomponentleakagetheestablishingininterestedV D ∼∼ 1.4 tocorrespondingbehaviorpre-RSTtheextrapolatingbyV V D <∼ 1 theuseWeV.
anddraintheandsourcethebetweensymmetryperfectaassuming7a,Fig.ofcircuit(a)curveDashed4a.Fig.ofdatathefromcharacteristicdiodesinglethetaking
resistancecollectoraAddingvanish.resistancesseriesthealllettingtocorresponds(d,c)downwardsitshiftsresistancesourceA(b).upwardscurvetheshifts – largein
fitgoodAcurrent.source-to-drainthewithassociateddropvoltagetheofbecausepartassumedofcombinationsofrangecontinuousawithachievedbecan R S and R C which,
ofuseTheway.thisindeterminedbecannotresistancestheseofvaluesthethatmeansisleakagetheofvalueasymptoticthethatfactthefromderivesprocedureour
ofvaluesactualthetoinsensitive R S and R C thetofitgoodagivetheyaslongso,region V D <∼ 1 toneedwouldweinstead,fittingsplinesimpleausetotriedweIfV.
asymptotehorizontaltheforvalueaspecify – alackingdeterminedbecannotwhichbasis.physical
----
S D
C
RS
RC
RD
(a)
|0.0
|0.5
|1.0
|1.5
|2.0
|0.2
|0.4
|0.6
| | | | |
||
|(b)T = 235 K
a
b
c
d,e
Drain Bias VD, V
Col
lect
or C
urre
nt I C
, mA
= 2.5 V
[Ω]a:
RS0
RC0
VC
b: 0 400c: 40 0d: 12 0e: 22 320
7Fig. current.leakagetheofestimationforproceduretheofIllustration:Thecurrent.RSTnoassumingchannelemittertherepresentssymbolFETThemodel.Circuit(a)
tocorresponddiodes pn resistorstheandcontactsdrainandsourcetheunderheterostructureR S, R D and, R C paths,currentcollectoranddrain,source,theinresistancesseriesparasitictorespectively.
andtemperatureparticularaatcurrentleakagetheofEstimation(b) V C theofCharacteristic.fromtakenarecharacteristicsDiode6b.Fig.fromtakeniscurrent)channel(thesymbolFET
symmetric,assumedareresistancesSeries4.Fig. R D = R S .
curves,leakageThe I CLKG (V D) valueeachforfashionindicatedtheindetermined,
of V C curve,leakagetheSubtracting6b.and6aFigs.inlinesdottedthebyplottedare,currentRSTthetoapproximationreasonableaobtainwe I C
RST Thusbias.givenaatcurvescalculated I C
RST (V D) 4.Sect.inbelowusedare
ChannelORNANDSingleaofCharacteristics3.3
channels:threeformsactuallydevicelogicmulti-terminalThe 1 − 2 , 2 − 3 and,3 − 1 theindicatetoarrowanuseshallwedevicethisofdescriptiontheIn.source → room-typicaltheshows8Figuremeasurement.particularaindirectiondrain
channeltheinmeasuredcharacteristics,temperature 3 → 1 differentofCharacteristics.source-draintheunderasymmetryslightaistherebutclosely,quitecoincidechannels
theofmisalignmentoff-centerunavoidableantoduechannel,singleaininterchangetheThustrenches. 3 → 1 inmeasuredthosefromdifferentslightlyarecharacteristics
the 1 → 3 inoutcancelsasymmetrysystematicthis5,Sect.inshownAsconfiguration.gate.ORNANDtheofstates8theall
significantlyaredevicemultiterminaltheofcharacteristicsSingle-channelkeyThe2a.Fig.ofCHINTthree-terminalthefor6aFig.inthoseoverimproved
largertheinliesimprovement I CRST loweratachievedmoreoveriswhich, V C This.
presentTheresistances.parasiticofreductionatoattributedbecanimprovementofmeasurementatoitselflendsnaturallynature,multiterminalitsofbecausedevice,
resistanceseriesthe R foundhaveWe2.and1electrodesin R = (10 ± 1) Ω dominated,lowerslightlyhavetoexpectedbecanelectrodesouterTheresistance.contacttheby R .
The I CLKG is4a,Fig.ofcharacteristicsdiodetheusingcalculatedcontribution,
thisinassumedwasresistanceparasiticNoline.dottedboldtheby8Fig.inplottedsourcethewithassociatedareaemittertheinasymmetrytheincludedwebutcase,
(electrode 3 (electrodedraintheand) 1 floating.arecontactstwootherthewhen)
----
|0
|1
|2
|3
|4
|0.0
|2.0
|4.0
|6.0
|8.0
|10.0
|12.0
|14.0
| | | | |
||
||
||
||T = 300 K
ID IC
Drain Bias VD, V
Dra
in a
nd C
olle
ctor
Cur
rent
s I D
, IC [m
A] = 2.3 VVC 8Fig. current-voltagetemperatureRoom:
[ I C (V D and) I D (V D aofcharacteristics])3single-channel ˜ → collectorfixedaat1
bias V C = 3ElectrodeV.2.3 ˜ groundedis3and2Electrodesdrain.theasacts1and
linedottedboldThefloating.keptarecomponentleakagetheindicates I C
LKG ,5a.Fig.indatathefromcalculated
contrastedbeto8,Fig.ofcharacteristiccollectortheinpeakaofabsencetheNotechannelheavieratodifferencethisattributewepoint,thisAt6.Fig.indatathewith
two-accurateanrequiresanalysisconclusiveastructure;multiterminaltheindopingout.carriedyetnothavewethatdevicecomplementarytheofsimulationdimensional
|0
|1
|2
|3
|4
|0.0
|2.5
|5.0
|7.5
|10.0
|12.5
| | | | |
||
||
||
Collector R = 0
3 Ω 10 Ω 20 Ω 50 Ω 422 Ω
Drain Bias VD [V]
Col
lect
or C
urre
nt I C
[mA
]
resistance
|0
|1
|2
|3
|4
|0.0
|2.5
|5.0
|7.5
|10.0
|12.5
| | | | |
||
||
||
Source R = 0
3 Ω 10 Ω 20 Ω 50 Ω 422 Ω
Drain Bias VD [V]
Col
lect
or C
urre
nt I C
[mA
]
resistance
|0
|1
|2
|3
|4
|0.0
|2.5
|5.0
|7.5|10.0
|12.5
| | | | |
||
||
||
Drain
R = 0
10 Ω 50 Ω 187 Ω
Drain Bias VD [V]
Col
lect
or C
urre
nt I C
[mA
]
resistance
9Fig. resistances.seriesofeffectThe:characteristicsvoltageCurrent I C (V D aof)
3channelsingle ˜ → theundermeasured1ain(though8Fig.inasconditionssame
resistancesserieswithdevice)different R(inadded a (collector,the) b source,the)
(and c circuits.drainthe)
inResistors9.Fig.inillustratedisresistancesseriesexternaladdingofeffectTheeffectivelydropvoltageitseffect:similarahavecollectortheorsourcethewithseries
theinfieldelectricnormaltheaffectslatterThebias.collector-to-sourcethereducesonresistance,seriesdrainAchannel.theinconcentrationcarriersheettheandbarrier
samethethateffectthewithfieldchannellateraltheonlyreduceshand,otherthe I C ishigheraatreached V D.
current-voltagetheshowsItfinding.interestingandnewareports10Figureatbothcollector,groundedaforcharacteristics 300 andK 6 fieldelectricbuilt-inTheK.
at V C = 0 barriereffectivetheincreasesandelectronschannelofRSTtheopposes
----
For3a.Fig.cf.height, V D > 0 reverse-biasedaisdrainthenearcross-sectiondevicethe,pn 5aFig.inthosetosimilarbetocharacteristicstheexpectwouldOneheterojunction.
biasescollectorreversethefor V C < 0 curvesthebias,draincertainaatHowever,.I C (V D) currentthewithcurves,leakagereverse-biasthefromdepart10Fig.in
theinobservedbeennothasregimeaSuchmagnitude.ofordersseveralbyincreasingischanneltheandlowerisdopingemitterthewhere2a,Fig.ofstructure "normally
off" atpropertiestransportthethatso, V C = 0 investigated.properlybenotcannormally-ainthoseresemblecloselystructureORNANDtheofcharacteristicsChannel
region.anomaloustheinstructureparticularnoshowandtransistorfield-effecton
|0
|1
|2
|3
|4
||
||
|| | | | | |
||
||
||
300 K
6 K
10-14
10-12
10-10
10-8
10-6
10-4
Drain Bias VD [V]
Col
lect
or C
urre
nt I C
[A]
VC = 0 10Fig. current-voltageAnomalous:3channelsingleaofcharacteristics ˜ → at1
V C = temperatures.differenttwoand0linesSolidfloating.are3and2Electrodes
show I C (V D at) V C = ofPolarity.0 I C
thefromholesofflowthetocorrespondslinesDashedcollector.theintochannel
leakagecollectorreverse-biastherepresentThe5a.Fig.fromcurrent " breakdownsoft "
near V D ∼∼ 1.5 V ofRSTthetoattributedisholes.impact-ionized
corresponding(polaritycurrentcollectorreversetheofrisesharpthebelieveWeofvalueshighatchannel)theintocollectorthefromflowingelectronsto V D >∼ 1.5 canV
thetoimputedbe ionizationimpact byreleasedHoles,channel.theinelectronshotbyheatingsubstantialaundergoandsourcethetowarddriftdrain,thenearprocessthis
ofincreaseobservedTheway.thealong I C ofRSTaasinterpretedthusis minorityholes ofRSTthesuppressesthatfieldelectricsamethethatNotechannel.thefrom
ofInjectionholes.channelofRSTtheaidselectrons majority collectortheintocarriersluminescenceatorisegivenotdoes – experimentalourwithaccordanceiniswhich
increasesInGaAsinthresholdionizationthetemperatures,cryogenicAtobservations.ofvaluecriticalthedoessoandwideningband-gapthetodue V D thewhichat I C (V D)
theEvidently,curves.leakagecorrespondingthefromdepart10Fig.incurvestheofobservationsimplifiesitalthoughessential,notisstructurecomplementary
ofRSTThebias.reverseundercurrentleakagethereducingbyeffectRSTminorityinphenomenaionizationimpactstudyingfortoolpowerfulabecancarriersminority
channels.transistorfield-effect
CHARACTERIZATIONOPTICAL4.
thefromdetectedwasdevicesRSTcomplementarytheofElectroluminescenceaanddetectorGecoolednitrogenliquidausingsubstratepolishedtheofback 0.75 m
tocorrespondingenergyphotontheatpeakedspectrumaobservedWespectrometer.increasingwithshrinksbandgaptheAsInGaAs.inrecombinationband-to-bandthe
fromincreaseswavelengthpeakthetemperature, 1.56 µ atm T = 100 toK 1.59 µ andm1.60 µ (temperatureslowatMoreover,respectively.K,290andK235atm <∼ 100 theK)
increases.currentRSTtheasenergyhighertowardsshiftsslightlypeaktheofpositionToinjection.electronincreasingthetodueeffectband-fillingatoshiftthisattributeWe
suitableandphotodiodeGebroad-areaausedwepower,emittedtotalthemeasureoptics.focusing
powerlightmeasuredtheofdependencetheshow11Figures P L electrontheonvoltageheating V D ofvaluesdifferentandtemperaturesselectedat V C sametheOn.
theshowwegraphs "net" curvesRST I CRST (V D) The3.2.Sect.indescribedascalculated,
thethatisobservationnotablefirst P L (V D) toproportionaldegreegoodatoarecurves
----
I CRST (V D) totalthetothanrather, I C (V D) expect.naivelycouldoneas6,Fig.of
inratioon/offtheexceedsfar11)(Figs.ratioon/offopticalmeasuredtheAccordingly,temperatures.lowatstrikingparticularlybeingdifferencethecurrent,collectorthe
atEven T = 290 instructureRSTthewhereK, I C (V D) theagainstvisiblebarelyisorderanbyissignalopticaltheofmodulationcorrespondingthebackground,leakage
formagnitude:of V C = 3.0 in9isratioon/offtheV P L in1.1and I C thisoforiginThe.ismodulationofdepththesinceunderstood,clearlybemustperformanceremarkable
light-emittingtheofapplicationslogicroom-temperatureforimportanceparamountofdevices.RST
3.0 9.0 2.5 5.9 2.0 2.3
|0.0
|0.5
|1.0
|1.5
|2.0
|
(a)
T = 290 K
0
50
100
0.1
0.2
0.3
Drain Bias VD, V
Mea
sure
d Li
ght P
ower
PL,
nW
VC(V) PL on/off
Rea
l Spa
ce T
rans
fer
Cur
rent
I CR
ST, m
A
3.0 107 2.5 102 2.0 53
|0.0
|0.5
|1.0
|1.5
|2.0
|
(b)200
100
0
T = 235 K
0
0.1
0.2
0.3
0.4
0.5
Drain Bias VD, V
Mea
sure
d Li
ght P
ower
PL,
nW
VC(V) PL on/off
Rea
l Spa
ce T
rans
fer
Cur
rent
I CR
ST, m
A
|0.0
|0.5
|1.0
|1.5
|2.0
|
| | | | |
|
(c)
600
400
200
0
T = 100 K
0
0.5
1.0
3.5 > 104
3.0 > 104
2.5 > 104
2.0 > 104
Drain Bias VD, V
Mea
sure
d Li
ght P
ower
PL,
nW VC(V) PL on/off
Rea
l Spa
ce T
rans
fer
Cur
rent
I CR
ST, m
A
11Fig. ofcharacteristicsoutputOptical:temperaturesdifferentatdevice2aFig.the
biasescollectorand V C totalThe.powerlightmeasured P L byplottedis
theindicatelinesDashedlines.solidcurrent I C
RST measuredthefromcalculatedI C subtractingby I C
LKG inillustratedas,werecurrenttheofMeasurements7.Fig.dataopticalthewithsimultaneouslytaken
inpresentedthosefromslightlydifferandisratioon/offpowerlightThe6.Figs.
valuemaximumthedividingbycalculatedof P L thebeforevalueminimumitsby
RST.ofonset(a) T = (b)K;290 T = (c)K;235 T = K.100
ofdependencetemperaturethestudyingBy I C (V C) at V D = 0 concludedhadwe,theintoholesofinjectionthetoduemostlyisleakagecollectorthethat3.1Sect.in
contributenotdoesinjectionthisthatindicateclearly11Fig.ofdatatheNow,channel.bycausedareRSTtheandleakagethethatsignificantisItsignal.opticaltheto
efficiencyradiativelowervastlyahaveholesinjectedThecarriers.oftypesdifferentrecombinetheybeforecontactdrainorsourcethereachtolikelyaretheybecause
Theelectrons.withradiatively In0.52Al0.48As layeretch-stop b insufficientlyis2)(Fig.bytimeescapeholeestimated(thechannelemittertheinholesminorityconfinetothick
time).recombinationradiativethethanshortermuchislayerthisacrosstunnelingdopedheavilylayerstheinoccurtolikelyisrecombinationnonradiativetheofMostactivetheinconfinedarecollectortheintoinjectedelectronscontrast,Intin.with
ofrecombinationthetoattributedbecanoutputopticaltheofallVirtuallyregion.designimportantanimpliesThislayer.activecollectortheinelectronsinjected
thesuppresstoessentialisitratioon/offopticalthemaximizetoconsideration:becanholesoffluxdirectedoppositelytheregion;activetheintoelectronsofleakage
tolerated.
----
thebelowisleakagethetorelatedsignallightthe11c,Fig.temperatures,lowAtinratioon/offtheandlevelnoise P L aboveis 104 smallthetemperatures,higherAt.
ratioon/offtheconsequentlyandincreasescurrentleakagetheofcomponentelectronpronounced.lessiscurrentcollectortheandoutputlight-powerthebetweendisparity
powerlightmeasuredtheFrom P L (V D , V C) radiativeinternaltheestimatecanwefollows:aselectronsRSTtheofefficiency
ηq =h ην c t o
1________I C
RST
q ∆P L______ , (4)
where ηc ∼∼ 0.48 emissionisotropicanassuming(estimatedefficiencycollectiontheis%theover 2π metallization),surfacethefromreflectiontodueangle,solid t o ∼∼ 88 theis%
thebetweenwindows)and(lenscomponentsopticaltheoftransmissioncombinedanddevice,theanddetector h ν luminescencetheofpeaktheatenergyphotontheis
quantitythecurrent,leakagethetoduepowerlighttheforaccountTospectrum. ∆P L istoequaltaken P L (V D , V C) sametheatmeasuredpoweropticaltheminus V C lowerbut
V D hasonetemperatures,lowerAtRST.theofonsetthetoprior, ∆P L = P L .efficiencycollectionourthatfactThe ηc totalthebyforaccountedislow,is
anusednothaveWeangle.solidcollectiontheandloss,Fresnelreflection,internal(aperturenumericallowrelativelyThecoating.anti-reflection N A ∼∼ 0.34 beenhas)
oferroranMoreover,measurements.low-temperaturefordewaraofusethebyforced± 5 in% N A oferroranproducesfocus,ofoutslightlybeinglenscollectionthefrom± 10 in% ηc wasefficiencytheofdeterminationtheinerrorsystematictheNevertheless,.
wholetheduringadjustednotwassystemlensthesincemeasurements,allforsametheThemeasurements.ofset relative andtemperaturesdifferentatbehaviorefficiency
reliable.quiteconsideredbecanbiasesefficiencyradiativetheofbehaviortheintrendsbasictheshows12Figure ηq
peaktheaboveandnearthatfoundWebias.collectorandtemperaturevaryingundervaryingbymodulatednotisefficiencythecurrentRSTtheof V D thatmeansThis. ηq is
givenaatcurrentinjectiontheofindependentpractically T and V C 12Fig.indataThe.ondependencethepeak;RSTtheneartakenis V D below.discussedisrangewiderain
increasingwithdecreasesefficiencyradiativethefigure,thefromevidentisAslight-conventionalinasexplained,betolikelyisdependenceThistemperature.
higheratroleincreasingthebydevices,emitting T assuchprocesses,non-radiativeofrecombination.Auger 18
itself.currentleakagetheofefficiencyradiativetheconsidertoinstructiveisItparameterabycharacterizedbecanThis ηq
LKG withbut(4)Eq.inasdefined, ∆P L
byreplaced P L (V D = 0) and I CRST totaltheby I C Forbias.heatingzeroat V C = 3.0 andV
T = 290 K, 235 andK, 200 findweK, ηqLKG = %0.12 , %0.06 and, %0.04 Thisrespectively.,
dependence,temperature "opposite" thetoevidencefurtheragives12,Fig.inthattorecombinethatholesoffractionsmallatonotdueislightleakagethethatfact
leakagethetocontributionelectronsmallatobutchannelemittertheinradiativelycurrent.
increasingwithdecreasetoseenalsoisefficiencythe12,Fig.toReturninglowatonlyprominentiseffectThisbias.collector T <∼ 150 ofvariationsignificant(noK
ηq with V C atdependenceapparentthetemperatures;higheratobservedis T >∼ 200 inKlow-thesincemeaningfulnotis12Fig. V C errorexperimentalanwithinarepoints
Onecomponent).leakagetheofsubtractiontheinuncertaintythebyintroducedtheforexplanationpossible V C hotofinjectionthetorelatedbemaydependence
recombinetheywherelayer,confinementcollectorwide-gaptheintoelectronstheofweakeningmodel,thisWithinnonradiatively.† V C ofdependence ηq higherat
________________
detectedbenotwoulditlayer,confinementthefromcomponentradiativeawerethereifEven†substate.InPtheinre-absorbedbewouldoutputlightInAlAstheofallsinceexperimentally,
wide-gapthefromradiationsignificantaexpectnotwouldoneprinciple,ofmatteraasMoreover,travelthanlongerislifetimeradiativetheirandconfinedlongernoarethereelectronssincelayer,
----
highertoduepathmean-freehot-electronshorterabyexplainedbecantemperatureselectronsinjectedoffractionsizableathatfactThescattering.optical-phononofrate
barrier,secondthecleartotemperatures)lowerat(especiallyenergyenoughretaincantheand19Ref.example,for(see,transistorsballisticofstudiesfromknownwellisourthatfactthecontradictnotdoesinterpretationThistherein).citedliterature
inratescoolingelectronthebecausetails,hot-electronshownotdospectrameasuredknownareInGaAs 20 recombination.thanfasterbeto
|50
|100
|150
|200
|250
|300
|0
|10
|20
|30
| | | | | |
||
||
Temperature, K
InGaAs/InAlAs
VC = 2.0 V VC = 2.5 V VC = 3.0 V VC = 3.5 V
Inte
rnal
Rad
iativ
e E
ffici
ency
ηq
%
p-collectorCHINT
12Fig. internaltheofDependence:efficiencyradiative ηq latticetheon
biases.collectordifferentfortemperature
inconsistentisitFirst,interpretation.thiswithdifficultieshaveweNevertheless,theinpeaktheofunderstandingourwith I C (V D) attributedhadwewhichdependence,
theinreversalfieldato3.2Sect.in "hot-spot" wouldoneClearly,channel.theofregionourcontradictsThiscase.thisineffectballistic-transistortheofsuppressionaexpect
calculatedtheofdependencetheshowswhich13a,Fig.indata ηq heatingtheonvoltage V D ofvaluesseveralfor V C at T = 100 theofenhancementNoK. ηq atoccurs
voltagesheatingthe V D theabove I C peak.dramaticthenamely13a,Fig.offeaturestrikingmosttheconsiderNext,
Thecurrent.collectortheinstepsaccompanyingefficiency,theinstepsdownwardlargelyandhighrelativelyareefficiencytheofvalueslow-bias independent theof
thestep,currentfirsttheoflocationthereachesbiasheatingtheAsvoltage.†collectortocorrespondingcurvesMoreover,value.plateauloweratodropssuddenlyefficiency
(biasescollectorlower V C = 2.5and2.0 current-theinstepsnoaretherewhichatV),Foreither.efficiencyindecreasesignificantnoshowcharacteristics,voltage V C > 2.5 V,
nearhappensevidentlysomething V D ∼∼ 1.2 theofswitchingstep-liketheforceswhichVcurrent-voltagetheinStepsdrop.efficiencythewithaccompaniedisandcurrent
explainedusuallyareCHINTtheofcharacteristics 4,9,10,15,21,22 associatedinstabilityanbytheandfieldtheBothchannel.theindomainshot-electronofformationthewith
temperatureelectron T e leadmaycourse,ofthat,anddomainstheindramaticallyriseofenergyaveragehighertheofbecauselayer,confinementtheintoinjectionhigherato
wethenfactor,decidingtheisenergyinjectiontheifHowever,electrons.injectedincreasingwithstronglydowngoefficiencyradiativetheexpectshould V C valuesallat
of V D theofinterpretationballistic-transistorabovethewithtroubleThe. ηq (V C)(dropefficiencytheexplaintoitstretchcannotwethatnotisdependence that canwe
________________________________________________________________________________________________
contact.thetotimeindecreaseapparentThe† ηq isdetector)lightouroflimitsensitivitythe(nearbiasesheatinglowestat
scalesprocessessuchofrateThedefects.withrecombinationnonradiativetorelatedprobablyradiativetheexceedsitinjectioncarrierlowatandconcentrationminoritythewithlinearly
rate.recombination
----
low-thatfactthewithinconsistentclearlyisitthatbutdo!) V D ofvalues ηq arepractically independent of V C alternativeconsidertoledtherefore,are,We.
data.efficiencytheofinterpretations
2.0 2.5 3.0 3.5
|0.5
|1.0
|1.5
|2.0
|
26
24
22
20
18
T = 100 K
0
0.2
0.4
0.6
0.8
1.0
Drain Bias VD, V
Inte
rnal
Rad
iativ
e E
ffici
ency
ηq
%
VC(V)
Rea
l Spa
ce T
rans
fer
Cur
rent
I CR
ST, m
A
|0.0
|0.5
|1.0
|1.5
|2.0
|0
|5
|10
|15 (b)T = 100 K
22
23
24
25
Drain Bias VD, V
Cur
rent
s I C
, ID, I
S, m
A ;
Inpu
t Pow
er W
tot,
mW
Inte
rnal
Rad
iativ
e E
ffici
ency
ηq
%
= 3.5 V IS
ID
ICx10ηq
Wtotx0.5
VC
13Fig. efficiencyradiativeinternaltheofDependence: ηq voltageheatingtheon V D.indicatelinesDashedbiases.collectordifferentatPlots(a) I C 6c.Fig.from(efficiencyradiativetheofplotsSimultaneous(b) ηq currentssourceandcollector,drain,the),
(I D, I C and, I S (powerinputelectricaltotaltheandrespectively),, W tot).
bylatticetheofheatingnonlocalainvolvesexplanationpossibleaopinion,ourInmaylayeractivetheintemperaturelatticethepicture,thisInelectrons.hot
powerthetoduetemperature,ambientthefromdeviatesubstantially W e bydissipatedestimatedbecanpowerThisemission.optical-phononviachanneltheinhot-electrons
as
W e = Aτe
kTn e______ , (5)
where n spot,hottheatchannelemittertheinconcentrationcarriersheettheis A theandarea,hot-spot τe (T e) temperatureatelectronshotoftimerelaxationenergythe T e.
lowAt V D henceuniform,relativelyandlowischanneltheinfieldheatingthe T e lowisissoand W e shrinksdomainhot-electronaofformationThe. A timesametheatbut
increasesstrongly T e thereforeand W e channeltheinemissionphononHigherup.goeslowerahenceandlayeractivecollectortheintemperaturelatticehigheratoleads
atincreasetemperaturerequiredthe12,Fig.ofdatatheFromefficiency.radiativeT = 100 thanlessbyisK 50 ondependenceTheK. V C gatingfield-effectthefromresults
factortheby(5)Eq.inexpressedcollector,theofaction n (V C) isdomaintheAfter.ondependencetheformed, V D weak.is
partessentialaniscarriershotbyheatinglatticethethatstresstolikewouldWefollowingthebyoutruledisdevicewholetheofheatingJoulesimpleApicture.thisof
powerinputtotaltheConsiderobservation. W tot theinwhichtransistor,theintobygivenisconfigurationcommon-source
W tot = I C V C + I D V D . (6)
thatfoundwesurprise,ourTo W tot is continuous current-voltagetheinstepstheatcharacteristics.§ theofoneofbehaviortheshowswhich13b,Fig.inillustratedisThis
________________
§ previouslyinmeasureddataavailablethere-analyzedhavewedevice,presentourtoadditionInstepsall)not(butmostthatfoundwesurprise,ourTotransistors.injectionchargeunipolarreported
in I D, I C and, I S = I D + I C power.inputtotaltheinvariationcontinuousabyaccompaniedareslopetheonlyTypically, W tot (V D) deservesphenomenonthisbelieveWetransition.theatchanges
switchingofnaturetheonlightshedmayIttheoretical.andexperimentalbothstudy,furthertrajectoriescomplicatedintrinsicallyofbranchesdifferentbetweentransitions 23 phasedevicethein
----
withtogether13aFig.ofcurvesefficiency I D, I C, I S and, W tot theallwhilethatseeWe.atdiscontinuityaexperiencecurrentsterminal V D ∼∼ 1.2 remainsinputpowertotaltheV,
continuous.thatremarkusletmisunderstanding,avoidTo W e ofpartaonlyis W tot ofMost.
W tot Involume.largeaoverdistributedandphononsacousticbydissipatedishowever,,powerthecontrast, W e withelectronsbydissipated, T e > ∼ 0001 theintogoesK,
spot.hottheatphononsopticalimmobilerelativelyofgenerationlight-room-temperaturethe14Fig.indisplayingbySectionthisconcludeWe
(single-channelaofcharacteristicsvoltage 3 → 1 Thesedevice.multiterminaltheof)For8.Fig.inthosetoidenticalconditionsbiastheundertakenwerecharacteristics
theshowsalsofigurethecomparison, I CRST subtractingbyobtainedcurve, I C
LKG in(shownincreasescurrentinjectionthethougheventhatseeWeline).dottedboldtheby8Fig.
themonotonically, P L maximumahascurve – 11Fig.incurvesanalogousthelike –ahavenotdowetime,thisAtsteep.sonotismaximumtheafterdropthealthough
atbehaviordifferentahave14Fig.inshowncurvestwothewhyunderstandingclearV >∼ 2 8.Fig.belowcommentourcf.V,
|0
|1
|2
|3
|4
|0.0
|0.2
|0.4
|0.6
|0.8
|1.0 T = 300 K
0
5
10
ICRST
PL
Drain Bias VD, V
Mea
sure
d Li
ght P
ower
PL,
µW
Col
lect
or C
urre
nt, I
C [m
A]
= 2.3 VVC14Fig. light-voltageRoom-temperature:
3single-channelaofcharacteristics ˜ → at1biascollectorfixeda V C = ElectrodeV.2.3
3 drain.theasacts1andgroundedisThefloating.keptare3and2Electrodes
theindicateslinedashed I CRST curve,
subtractingbyobtained I CLKG from I C in
8.Fig.
LOGICTRANSFERSPACEREAL5.
statesinternalthebetween(1)equivalencesymmetryThe S [V D , V C] CHINTaoftoproportionaliswhichpower,opticaloutputitsthatimpliesdevice I C
RST isandbiasheatingthebycontrolled V DS drainandsourcetheonpotentialstheifinvariantis,
theofdependenceexclusive-ORanexhibitsdevicetheThusinterchanged.areterminalsvoltagesinputtheonpowerlightemitted V S and V D (high/low)binaryasregarded,
signals.logicThetemperatures.differentthreeatoperationlogicthisdemonstrate15Figures
atfixedisbiascollector V C = 3.0 fromvariedarevoltagesinputtheandV low = 0 tohigh = 1.5 opticalanofOperationV. xor showndataThe15a.Fig.inillustratedisgate
frequencythecharacterizetomadewasattemptnomeasurements;DCinobtainedwerethethatseeWeoperation.fastafordesignedbeennothaddeviceourasresponse,
powerlight-output P L obeys P L = xor (V S , V D) roomincludingtemperatures,allatthebetweenasymmetryslightThetemperature. on (states 0,1 (and) 1,0 thatindicates)
hand,othertheOnvariations.processingtoduesymmetricperfectlynotisdeviceourthebetweendifferencethe ffo (states 0,0 (and) 1,1 atoowingistemperatureshighat)
________________________________________________________________________________________________
26-30.and22Figs.below:cf.space,
----
current.leakagethewithassociatedradiationnonvanishingleakagethewithassociatedefficiencyradiativelowthethatstressedbeshouldIt
successfulaforcrucialiscurrent xor 15bFig.comparison,Fordevice.ourofoperationbiasingandtemperaturessimilaratdeviceourofbehaviorelectricaltheshows
thebetweensymmetryapproximatetheWhileconditions. on (states 0,1 (and) 1,0 is)functionthemaintained,well I C = xor (V S , V D) temperatures.cryogenicatonlyobtains
higherAt T (statetheinholesofleakagethe, 0,0 aneffectivelyitmakes) on andstatealikemorelooksfunctionresultingthe nand athan xor.
Time
VD
(V)
SV
(V)
P L(n
W)
Mea
sure
d Li
ght O
utpu
t
1.5
1.5
Time
1-0 1-1 0-1 0-0
1 0 1 0
T = 290 K
T = 235 K
T = 100 K
130 110
390260
80 702
0
0
(a)
Out :
10
20.1
< 0.1 < 0.1
(b)
Time1 0 1 0
T = 290 K
T = 100 K
0
0
1
1
SV
(V)
0
Time
VD
(V)
1.5
1.5
1-0 1-1 0-1 0-00
Out :I C
(mA
)C
olle
ctor
Cur
rent
T = 235 K
0
1
2 1.87
0.4
1.81
2.5
0.98 0.87 1.14
0.520.36
2x10-45x10-8
0.06
15Fig. atCHINTcomplementarytheofoperationlogicelectricalandopticaltheofComparison:temperaturesdifferent T 1(stateslogicFour. − 1(),0 − 0(),1 − 0(and),1 − thetocorrespond)0
(inputselectrical V S − V D valuesthetaking) V = and(logic-0)0 V = 1.5 V (logic-1).output,Optical(a) P L tocorresponds, xor (V S, V D allat) T temperature.roomincluding,
output,Electrical(b) I C is, xor (V S, V D temperatures.cryogenicatonly)
anCHINT:light-emittingtheofapplicationpossibleanotherdiscussbrieflyusLetresponsedevicetheConsidersignal.†inputelectricaltheofdoublerfrequencyoptical
voltagetheofvariationsinusoidalato V D electrodes,emittertheofoneon D keeping,electrode,otherthe S grounded,, V S = 0 foroutputlightThe. V D rangetheinvarying
− V2 < V D < 2 ofvaluesfixedseveralandV V C toresponsetheand16a,Fig.inshownis,ofvariationsinusoidala V D thesituation,thisinthatNote16b.Fig.inillustratedis D
whenhalf-periodtheduringelectrode V D < 0 effectivethethatsosourcetheactuallyisfield,collectortheofactiongatingtheofBecausevaried.isvoltagecollector-to-source
uneveninperiodpertwicecomesoutputTheasymmetric.arecharacteristicsthefinitetheofbecausepossible,isdevicethisofoperationsmall-signalNopulses.
RST.tangibleainitiatetorequiredvoltageheatingtheofmagnitudeCHINTtheofapplicationssmall-signalfrustratesRSTtheofnaturethresholdThe
al.etMenszNevertheless,(1).symmetry 8 CHINTtheofoperationunipolarareportedawithlevelleakagetheupdrivingintentionallyBydoubler.frequencyelectricanas
totalthewhereregimeafoundtheybias,collectorhigh I C (V D) appearscharacteristicopticalanobtainingofpossibilitythetoregardsasarisesquestionnaturalAparabolic.
isthisstructurepresentourIndoubler.frequencysmall-signalasuchofanalogleakagethewithassociatedefficiencyradiativelowtheofbecausepreciselyimpossible
________________
privateainIgaK.Professorby(SL)usofonetosuggestedbeenhadapplicationanSuch†(1990).communication
----
whichinheterostructuresusingachievedbecanoperationansuchPerhaps,holes.ofin(e.g.typecarriersamethetoduemostlybewouldRSTtheandleakagetheboth n -
whereInGaAs/InP,inimplementedCHINTcomplementarychannel ∆E V > ∆ E C Of).thestructureasuchincourse, on/off current.andlightbothinsamethebewouldratio
InGaAs/InPainoperationlogicelectricaltheoveropticaltheofsuperiorityrecoverToausetohavewouldoneCHINT,complementary p emitter.-type
3.5 3.0 2.5 2.0 1.5 1.0
| | | | | | ||0.0
|0.2
|0.4
|0.6
|0.8
| | | | | | |
||
||
|
-2.0 -1.5 -1.0 2.01.51.00XX
(a)T = 100 K
Drain Bias VD, V
Mea
sure
d Li
ght P
ower
PL,
µW
VC(V)
| | | | ||-2.0|-1.5
|-1.0
|-0.5
|0.0
|0.5
|1.0
|1.5
|2.0
Time
(b)T = 100 K
0
0.0
0.1
0.2
0.3
VD
PL
Hea
ting
Bia
s V
D, V
= 2.5 V
π/2ω π/ω 3π/2ω 2π/ω
Mea
sure
d Li
ght P
ower
PL,
µW
VC
16Fig. atillustratedformation,pulseopticalDouble-frequency: T = K.100rangetheinvaryingvoltageheatingtheforoutputOptical(a) − 2.0 < V D < + severalandV2.0
groundedaForbiases.collectorfixed S negativeandelectrode V D theisit, D thatelectrodenearscalevoltagebrokentheNotesource.aofroletheplays V D ±= V.0.5
signalopticaltheofevolutionQuasi-stationary(b) P L sinusoidalatoresponseinline)(solidvoltageheating V D line).(dashed
LogicORNAND5.1
conditionsboundaryperiodicthesetweSince V 3 = V3 devicemulti-terminalour,electrodecontrolaasviewedbecantheseofOneterminals.inputthreeeffectivelyhas
functionslogictwotheofwhichdetermineswhich or or nand othertheonexecutediscurrentcollectorThearbitrary.iselectrodecontroltheofChoiceinputs.two I C theand
powerlight P L withstatesthetorefershallWeoutput.logictherepresent high and lowasoutputtheofvalues on and ffo respectively.states,
ORNANDtheofoperationlogicroom-temperaturethedemonstrates17FigureausingsubstratepolishedtheofbackthefromdetectedbeenhassignallightThegate.
polishedbeenhasthicknesssubstrateThelight.thecollecttoobjectivemicroscopetodown 35 µ isbiascollectorThesubstrate.theinabsorptioncarrierfreethereducingmatfixed V C = 2.4 signalsinputtheandV V1 and V2 betweenvariedare low = 0 and
high = 3 theateitherfixediscontrol,theaschosenelectrode,splitthewhileV, low valueV3 = 0 thefor or theatorfunction high value V3 = 3 theforV nand function.
----
17 18 18 1816 16
0 .066
33 3335 36 3440
60
10
20
20
40
1
V3
V2
V1
IC(mA)
PL
µW( )
nand or
0
1
0
1
0
time17Fig. logicelectricalandOptical:
obtainedgate,ORNANDtheofoperationroomatmeasurementquasi-stationaryain
andtemperature V C = 3ElectrodesV.2.43and ˜ valuesbinaryThetogether.tiedare
"logic-0" and "logic-1" signalsinputtheofV1, V2 and, V3 ,V3and0tocorrespond
ofgroupingparticularTherespectively.thereflectsNANDandORintostatesthe
ofchoice V3 theas "control" electrode.
differentbetweensymmetrythe17,Fig.fromseenAs on maintained,wellisstatesforboth I C (± 8 and%) P L (± 6 invariationlargerThe%). I C theinvariationthetodueis
Differentholes.ofcurrentleakage on areasdifferenttocorrespondstates A S theofcontact:source A S is 25 forareaemittertotaltheof% nand (0,1) and nand (1,0) while,
A S = 75 for% or (0,1) and or (1,0) and, A S = 50 for% nand (0,0) and or (1,1) thelargerThe.Sincecurrent.RSTthetoaddediswhichcurrentleakagetheislargertheareasource
ofefficiencyradiativethe I CLKG ofthattocomparednegligibleis I C
RST the, on arestatesofefficiencyradiativelowTheoutput.lightmeasuredtheinhomogeneousmore I C
LKG
thethatfacttheexplainsalso ffo theofstate or electricallyperfectthanlessisfunctionratio(the on ⁄ ffo ∼∼ 7 in I C (opticallysatisfactorythanmorewhile), on ⁄ ffo >∼ 200 in P L In).
the ffo theininjectedholesfromresultsleakageofmostandRSTnoistherestatelayer.emitter
basictheofviolationforcauseonlythenotisareasourceeffectivetheinVariationchannel-thedisplacetoissymmetrythisbreaktowayAnother(1).Eq.symmetry
theintrenchdefining n + middletheinexactlypositionnominalitsfromlayercapsingle-channeltheshows18Figureelectrodes.neighboringbetween I C
RST (V D)sourcedifferenttwoandchannelsdifferenttwoforcharacteristics → orientations.drain
channelsdifferenttwoinorientationsamethetocorrespondingcurvesthethatseeWeThisorientations.differentbutchannelsametheforthosethancloselymorecoincide
presenttheindatathethatremarkWeexamined.devicesallfortrueholdsobservationtheofalignmentluckyexceptionallyanwithwaferafromcollectedbeenhavereportthebetweendifferencethewafers,otherInmasks.metalsource/draintheandtrenchhasthisNevertheless,larger.evenischannelsametheoforientationsoppositeinRST
ofsymmetrytheoneffectno on symmetrytheIndeed,gate.ORNANDtheinstateschannels,threetheallinidenticalbetohasmisalignmenttrenchatoduebreak
sixtheofeachthatNoting2b.Fig.cf. on fieldunderchannelstwohasstates – ofoneorientationeach – ORNANDtheinoutcancelsasymmetrysystematicthethatseewe
18.Fig.inTablethecf.operation,logic
----
1 2
1~3
2 1
1~3
L RR L
= 300 K= 2.3 V
TVC
|0
|1
|2
|3
|4
|0.0
|2.5
|5.0
|7.5
|10.0
|12.5
| | | | |
||
||
||
Drain Bias VD [V]
RS
T C
olle
ctor
Cur
rent
I CR
ST [m
A]
2 32 11
~3
1 21
~3
2 3
3 2
~3 1
2 1
~3 1
3 21 2
0 0 1 11 0 0 1
V3 = 0
V3 = 1
or
V1 V2, , , , ,
nand
input
18Fig. The2b.Fig.ofgateORNANDtheintrenchesofmisalignmentthetodueAsymmetry:sourcetheindicatesarrow → Thus,misalignment.trenchthepositionitsandorientationdrain
symbolthe S →D (drainthetocloseristrenchthethatindicates D figureTheelectrode.)differenttwoinfieldchanneltheoforientationsoppositetwoforRSTtheofcomparisonashows
currentleakageThechannels. I CLKG indicatesrighttheontableThe14.Fig.inassubtracted,is
theofstateslogicallinfieldheatingtheunderarethatchannelsthosei.e.channels,workingthegate.
----
COLLECTOR-CONTROLLEDANDINSTABILITIESHOT-ELECTRON6.STATES
theabove,seenhaveweAs IV aretransistorsinjectionchargeofcharacteristicsthein(NDR)resistancedifferentialnegativestrongaincludingnonlinear,extremely
I D (V D) (MC)CarloMonte8.or6Fig.e.g.,cf.,steps,sharpwithdependencesimulations21,22 offormationtheandswitchinginternaldemonstrateCHINT,theof
RSTthebetweenfeedbackpositiveatodueariseinstabilitiesThesedomains.high-fieldmeasurementsexperimentalBothchannel.emittertheinfieldelectricheatingtheand
ofrestrictionthetodueeffectsRSTanalyzinginlimitedbeenhavecalculationsMCandtracing IV theinprogressSignificantincrements.voltageinexclusivelycharacteristics
achievedwasinstabilitiesRSTtheofunderstanding 9,23 continuationofhelpthewithsimulation.devicetransientandmodeling
forimportantistransistorsRSTindomainshot-electronofstudyThethetocontrolelectron-heatingtheofSwitchinglimitations.deviceunderstanding
Theamplifier.linearaasusedbecanCHINTwhererangetherestrictscollectorthebyonlylimitedbetobelievedismodeusualitsinCHINTofperformancefrequency
ofdistancesoveri.e.,device,theofregionshigh-fieldoverelectronshotofflightoftimethefromextrapolatedfrequencies,cutoffThethickness.barrier-layertheorder
measurementsmicrowave 24 withstructureCHINTunipolarainparametersscatteringofa A2,000 ˚ transitthegain.powertheandcurrentthebothforGhz40werebarrier,-thick
unity-gainforlimitupperthesetswhichps,2-3orderofbetoestimatedbecantimeachievedbecanperformancespeedultimateTheGHz.50aroundatfrequenciescutoff
layer.toptheiscollectorthewhichinstructureCHINTinvertedanwith 25−27 allowsThisnarrowerofusethethereforeandcapacitancedrain-collectorparasitictheofreductiona
aoutperformtoexpectedbecanCHINTthebarriers,narrowsufficientlyWithbarriers.FETthetocorrespondingcollectorRST(thegeometrysimilaroftransistorfield-effect
limitednotisCHINTofperformancesmall-signalthebecauseetc.)gate, 1 oftimethebydemonstratedrecentlywasadvantageThisdrain.theandsourcethebetweenflight
experimentally.26 FET-like,longer,abetoseemsitselfformationdomaintheHowever,below.25and20Figs.cf.process,
simulationnumericaltheofResults 9,23 three-aintransporthot-electrontheofsimulationstwo-dimensionalofnumberAbelow.reviewedarestructureRSTterminal
(channelgeometrydevicethevaryingperformed,beenhaveCHINTunipolaraoflength L CH thicknessbarrierand d B biasexternaltheandparameters,transport),
investigated.beenhaveproblemstime-dependentandstationaryBothconditions.
ModelMathematical6.1
directlymusteffectstransferreal-spaceforaccounttoattemptswhichmodelAnyNeumannofformsomespecifytoabilitytheFurther,heating.carrierfortermsinclude
multivaluedarbitrary,tracingforessentialisconditionsboundary IV characteristics.PADREsimulatordevicegeneral-purposethebymetarerequirementstheseofBoth 28
BoltzmanntheofmomentsfromderivedequationsdifferentialpartialsolveswhichsystembalanceenergyanemployedbelowdescribedSimulationsequation. 3029, defined,
potentialelectrostatictheoftermsin ψ densityelectronthe, n electrontheand,temperature T e elsewhere.listedareusedequationsPrecise. 31
domaindeviceadecomposesPADREstructure,dataelement-basedanThroughofnumberanyinstance,forregions;ofconfigurationsnonplanararbitrary,into
verticestheatData(node).locationsingleaatabruptlyterminatecanheterointerfacesimpurityThedependencies.modelandmateriallocalhavecanelementeachof
anyacrossabruptlychangetoallowedarevariablessolutionandconcentrationandlevelquasi-Fermitheanalysis,thisIninterface.heterostructure T e assumedare
aintroducingthuscontinuous, T e localonconditioninterfacetheindependencedensityelectron n isbarriersenergyatdensitycurrentRSTthethatmeansthis;
self-consistently.includedandthermionic
----
forModels µ and τe offunctionaas T e user-definedfromderivedtypicallyarevelocity-fieldMC)(e.g. v (F ) temperature-fieldand T e(F ) homogeneousforrelations
fromarisingeffectsmobilitydifferentialnegativewithconfusionavoidToslabs.awithusedbeenhaselectronsofpopulationsingleatransfer,spacemomentum
monotonic v (F ) µ= 0F [1 + (µ0F ⁄v sat)2] − 1⁄2 relation32 thewithtogether T e(F ) abyimplied T e-diffusivity.independent 33 realisticmoreforsimilarqualitativelyremainresultstheAll
v (F ) and T e (F ) wereeffectstunnelingandionizationimpactreasons,similarFor.assystemInGaAs/InAlAsthematchtoselectedwereparametersOtherexcluded.
possible.asexactlycomplexthetracetoorderIn IV applytonecessaryisitbelow,showncurves
continuationpredictor-correctorTheconditions.boundarycurrent/voltagemixedmethod34 pseudo-arclengthaonbased σ Computationally,purpose.thisforusedwas
equation,auxiliaryalgebraicsingleaofadditiontherequiresmethodcontinuationthecurrentandvoltagetheoftermsinwrittentypically (Vj , Ij ) tangentunittheand (V
.j , I
.j )
curvetheonpointknownaat j limitdetecttousedbealsocantangentunitThe.where(e.g.points V
.= 0 or I
.= 0 biassubsequenttheforguessinitialanpredicttoand)
point j +1 auxiliaryassociatedandmethodcontinuationtheillustrates19Figure.here.usedpseudo-arclengththeoncondition
j
j+1
δj+1
∆σ j
19Fig. continuationPredictor-corrector: 34
pointsconsecutivebetweensteptoappliedj and j + anon1 IV Thecurve.
I.j (I − Ij ) + V
.j (V − Vj ) − ∆σj = 0
steppseudo-arclengthnextthewhere ∆σj +1user-abycontrolledautomaticallyis
theoferrortheontolerancespecifiedprojectiontangential δj .
DomainsRSTofFormationandSymmetryBroken6.2
Ramping.Rapid withdeviceaofsimulationtime-dependentaillustrates20FigureL CH = 5 µ andm d B = 0.2 µ Bothm. S and D whilegrounded,keptareelectrodes V C is
fromrampedlinearly 0 to V C = 2 timerampingtheonDependingV. τ settlesdevicetheforstates:twoofonein τ > τcr forwhereasstate,normal†theisit τ < τcr steadythe
bydeterminedisspeedrampingcriticalThe20a).(Fig.currentRSTlargeacarriesstateelectrons.channelbyscreenedis20b)(Fig.fieldfringingincreasingthewhichatratethe
ofvalueThe τcr ∼∼ 32.3 fromtravelelectronoftimethetocorrespondsroughlyps S andD channel.theofmiddlethetocontacts
atstateanomalousThe V D = 0 highsufficientlyaforonlyexists V C valuetheand,of V C
cr andgeometrydevicetheondependsdisappears,statethiswhichbelow, v sat.ofvalueThe V C
cr voltageendramptheforanddefined,sharplyis V above V Ccr hasone,
τcr ∝ V criticalrelevantthethatindicatesThis21a.Fig.cf.approximation,goodato(currentdisplacementtheisparameter ∝ dV ⁄dt atocomparedbeshouldwhich),
(currenttransient ∝ v sat emitter.theinprocessesscreeningelectronwithassociated)
________________
aIn† "normal" fordevice,theofstate V DS = 0 determinedcurrent,minimalaonlydrawscollectorthe,ofvariationastatethisIntemperature.theandheightbarriertheby V C ofeffectsolethehas
channel.theinconcentrationelectronthetransistor,field-effectainascapacitively,changing
----
|0
|10
|20
|30
|40
|50
|0
|2
|4
|6
|8
Time, psec
t1: VC= 1 V t2: VC= 2 V t3: VC= 2 V
Col
lect
or c
urre
nt I C
, A/c
m
S LCH D
n- InGaAs 500 A
u InAlAs dB
n+ InGaAs
C
|0
|1
|2
|3
|4
|5
|0
|1
|2
| | | | | |
||
|
Pot
entia
l, V
t1 t2 t3
Distance, µm
20Fig. withtransistortransferreal-spaceaofsimulationTime-dependent. L CH = 5 µm,d B = 0.2 µ andm, v sat = 107 fromlinearlyrampedisvoltagecollectorThecm/s. V C = at0 t = to0V = atV2 t τ= situations:twoforplottedareresultsThe. =τ ps32.0 < τcr andlines)(solid
=τ ps32.5 > τcr lines).(dashed(a) figureleft currentCollector: I C (t Dottedstructure.devicetheofcross-sectionshowsinset;)
byobtainedisitcurrent);displacement(pureRSTaofabsencethetocorrespondscurveheight.barriertheincreasingartificially
(b) figureright distributionPotential: V (x times.selectedatchannelthealong)
ofvaluesThe τcr withintodetermined, 0.1 theagainst21bFig.inplottedareps,lengthchannelemitter L CH ofvaluesassumeddifferentfor v sat andthicknesses,barrier,
voltagesendramp V shortFor. L CH dependencethe τcr (L CH) quadratic,approximatelyislongforand L CH linear.isdependencethe
|0
|1
|2
|3
|4
|5
|6
|0
|25
|50
|75
|100 | | | | | | |
||
||
|
Maximum collector voltage VC, V
Crit
ical
ram
ping
tim
e τ c
r, ps
Lch
= 5 µm
Db
= 0.2 µm
vsat = 107 cm/s
612 311 312 212 321 322
| | | | | |1
| | | | | | | | |10
|1
||
||
||
||
|10
||
||
||
||
|100
|
| | | | | | | | | | | | | | |
||
||
||
||
||
||
||
||
|||
|
Channel length Lch, µm
Crit
ical
ram
ping
tim
e τ c
r, ps
21Fig. atstatestableanomalousstableaofformationtheforspeedrampingCritical. V D = .0linearlyrampedisbiascollectorThe V C = 0 → V intervaltimethein τ For. τ > τcr devicethe
forstate,normaltheinsettles τ < τcr (stateanomalousthein d 22).Fig.ofnotationtheinfigureLeft ofDependence: τcr 5aforvoltageendramptheon µ device.m V C
cr = V.1.21figureRight labelsCurve: VSD (voltageendramptheindicate V velocitysaturatedthevolts,in)
(S 10in) 7 cm⁄ (thicknessbarriertheands D A1000in) ˚ indicatelinesstippleanddashedThe.respectively.dependences,quadraticandlinear
CharacteristicsStationary atstatesstationarytwothefromStarting. V D = 0 possibleisit,characteristicsthedetermineto I D (V D) and I C (V D) voltagecollectorfixedaat V C = 2 V
thetorelative S methodcontinuationpredictor-correctortheWithelectrode. 34 canone,anyfromstartingcharacteristic,theofcomponentsconnectedshaped,arbitrarilytrace
locusthetocorrespond22Fig.incurvesThecomponent.eachwithinstateestablished
----
theinpointsof (V D, I D) givenaatstatesteadyahasdevicethewhichforplane V C To.displayedtheknowledge,our I D (V D) aofexamplefirsttherepresentsdependence
disconnectedbetweentransitionAnycharacteristic.current-voltageconnectedmultiplyfieldsstatetheofredistributionglobalarequiresgraphtheofcomponents
high-temperaturehigh-field,ofrepositioningorformationthetocorrespondingistransition,phaseaofreminiscentredistribution,aSuchstructure.theindomains
asforced V D (pointrightmostthebeyondincreases k component.graphboundedtheof)profilespotentialThe V (x ) channelthealong – transitiontheafterandbefore –
states,collector-controlledthreetheOf23.Fig.inshownare s, t and, u corresponding,(sametheto V D ∼∼ 0.82 statetheasbiasexternalV) k (two, s and u actualThestable.are)
statetheintooccurstransition u current.collectortheofvaluehighestthehaswhichstateinitialthewhichinsimulationtime-dependentabyascertainedbeenhasThis k
stepsmallabyperturbedwas V D (k) → V D (k) δ+ V D theindomainshot-electronThe.state u risedramaticabyaccompaniedconcentration,fieldstrongabycharacterizedarein T e fieldcollectorthethatsodepletedisdomaintheinconcentrationelectronThe.
ainresultingdrain,theofthatbelowgoespotentiallocaltheandunscreenedremainsnegative I D theonstatesAll. p − u − d arecomponentcollector-controlledtheofbranch
tosimilar u stable.perfectlyand
|-1.0
|-0.5
|0.0
|0.5
|1.0
|1.5
|2.0
|-4
|-3
|-2
|-1
|0
|1 | | | | | | |
||
||
||
Source-Drain Voltage, V
Dra
in C
urre
nt,
A/c
m
o
ab
c
d
k
s
t
u
q
p
VC= 2 V
|0
|1
|2
|3
|4
|5
|0.00
|0.25
|0.50
|0.75
|1.00
|1.25
|1.50
|1.75
|2.00
| | | | | |
||
||
||
||
|
Pot
entia
l, V
k
s
t
u
Distance, µm
22Fig. characteristicsCurrent-voltage.method.continuationthebyobtained
23Fig. profilepotentialchannelThe. V (x )sametheatstatesCHINTdifferentin
(biasexternal V C = ,V2 V D = V).0.825
statethatindicatesThis d oframpingrapidinfoundfirsthadwe(which V C at V D = 0,ofvariationquasi-staticabyaccessibleexperimentallyis20)Fig.cf. V D fixedat V C The.
stateanomalousstableaofexistence d insufficient)(thoughnecessaryaobviouslyistheoftopologymultiply-connectedtheforcondition I D (V D) discussedAscharacteristic.
fringingtheofscreeningandRSTbetweencompetitionthewhenresultsitabove,theondependshappensthiswhenPreciselyRST.offavorinresolvedisfieldcollector
geometry.devicetheandassumedparameterstransport
statesanomalousUnstable statenormalthetoadditionIn. o stateanomaloustheand d,(statesanomalousotherthreereveals22Fig. a , b and, c at) V D = 0 profilesThe. V (x )
24.Fig.inshownarestatestheseinchannelthealongactualtheproblem,theofnaturenon-lineartheofbecausethatclearisIt
theofrepresentationsirreducibletoaccordingtransformnotmaystatesstationaryatbehaviordevicethegoverningequationstheofgroupsymmetry V D = 0 The.
theseorsymmetricfullyeitherisstatesanomaloustheinfieldsinternalofdistributionsymmetrytheunderanotheroneintotransformandpartnersofsetaformstates
statesThus,operations. a and c thoughevenother,eachintotransformreflectionunderstateshand,othertheOnrepresentations.linearone-dimensionalonlyhasgroupthe o,
b and, d theBiasingsymmetric.are D torespectwithelectrode S reflectionthebreakssymmetrydifferentofstatesbetweentransformationcontinuousaallowsandsymmetry
----
loop.theon
|0
|1
|2
|3
|4
|5
|0.35
|0.50
|0.65
|0.80
| | | | | |
||
||
Pot
entia
l, V a
b
c
d
Distance, µm
24Fig. fourtheinpotentialchannelThe.atstatesanomalous V D = 0.
atstatesfivetheOf V D = 0 and V C = 2 (twoonlyV, o and d respectwithstableare)instatesofevolutionthefollowingbyascertainedbeenhasThisperturbations.smallto
atstatessteadytheofvicinitythe V D = 0 statesinitialthe25,Fig.simulations,theseIn.a ± , b ± and, c± fromdisplacedlooptheonstateawithcoincidetoassumedbeenhavea , b and, c voltageinfinitesimalanbyrespectively,, δV D ±= 10 thesethoughEvenmV.
foundweones,stationarycorrespondingthefromindistinguishablevirtuallyarestatesthat a + , b − and, c− intoevolved o while, a − , b + and, c+ into d instabilitiestheseAll.
ofdistancestheovertravelelectronthetocorrespondingscale,timerapidaondevelopaof(repositioning)formationtheeitherinresultTheysize.domaintheoforderthe
electrons.channelbyscreeningthetoduequenchcompleteitsordomain,hot-electron
|0
|10
|20
|30
|40
|0.0
|2.0
|4.0
|6.0
|8.0 | | | | |
||
||
|
time, psec
Col
lect
or C
urre
nt I C
, A/c
m
|0
|1
|2
|3
|4
|5
|0.0
|0.2
|0.4
|0.6
| | | | | |
||
||
Distance, µm
Ele
ctro
n T
empe
ratu
re T
e, e
V
25Fig. statesnon-stationarytheofEvolution. c+ andlines)(solid c− atlines)(dashed V D = .0inshowniscurrentinjectiontheofdependenceTime figureleftthe selectedthemarksymbols;
inplottedareprofilestemperatureelectronthewhichatevolution,theintimes figurerightthe .The "plateau" thein I C (t neardependence) t = whensituationthetocorrespondsevidentlyps20
nearalreadyexistsdomainhot-electronfully-developeda D thenearyetnotbut S electrode.
ascertainedbeusuallycanstategivenaofstabilityofquestionthethatNotewithout simulationstime-dependentcostly – diagramsphasetheinspectingbyI D (V C,V D) and I C (V C,V D) statesofinstabilityThebelow.discussed a and c associatedis
theinNDRawith I C (V C) dependence, ∂I C⁄∂V C < 0 ofthatand, b bothwith ∂I C⁄∂V C < 0and ∂I D⁄∂V D < 0 found.beenyethasrulethistocounterexampleNo.
characteristics.current-voltageCHINTofmappingsDC shows26Fig. I D (V DS)atdevicesingleaforcharacteristics T = 300 voltagescollectorfixedofseriesausingK
----
(V CS topologicalnumerousshowscharacteristicstheofexaminationClose).lowatFETmodeaccumulationanasBeginningtransformations. V CS (< 1.0 onsettheV),
theinregionNDRslightaofformationtheinitiatesRSTof +V DS (direction ∼∼ 1.0 AtV).higher V CS bothforappeartobeginfoldsseparate, V DS > 0 and V DS < 0 thealthough,
Atconnected.singlyremaincurves V CS ∼∼ 1.2 inappeartobeginsloopdisconnectedaV,minimumabyboundedsurfaceatocorrespondingplane,left-handthe V CS 3Dthein
(27Fig.inshownAs26.Fig.inspace V CS = 1.5 needle-liketheandloopclosedthisV),theandopen,tocontinuebothplaneleft-handtheofbottomthefromemanatingfold
frombackwardstracingbyreachedknee(theplaneright-handtheinnotch‘‘S-shaped’’V DS ∞+= asleftwardmoves) V CS Byincreases. V CS = 1.6 ischaracteristictheV,
componentconnectedsinglyaandorigin,theincludeswhichloopaintotransformedtwoTheseloop.thewithintersectionsorfoldsnohasbutmultivaluediswhich
largerfortopologysametheessentiallymaintaincomponents V CS theiralthoughinseparation (I ,V ) 22.Fig.cf.increases,
-2
2 1
2
-0.3
0.1
VDS (Volts) VCS(Volts)
ID(mA/µm)
26Fig. CHINT: I D-V DS forcharacteristics1.0V ≤ V CS ≤ (2.0V L CH = 5µm, d B = 0.2µm,v sat = 1×107cm⁄ representCurvess).
constantatsimulations V CS byseparated∆V CS = 0.1V.
anomalousofmultiplicitytheNote V DS = 0 atgeneral,Instates. V DS = 0 canwe,numberoddanexpect m S numberevenanandstatessymmetricof m A asymmetricof
theinpathunboundedoneonlyandonebealwaysshouldtherebecauseones, (V DS , I D)Varyingpairs.incomestatesasymmetricsymmetry,bywhile,plane, V CS havewe,
(withcasesrealizetoablebeen m S, m A) = 4)(5,and4),(3,2),(3,,0)(3,,0)(1, aIn.ofvariationcontinuous V CS thewhensituationaatarrivecourse,ofcan,one I D (V DS)
thetouchesonlycurve V DS = 0 anistherepointsingularthisAtcrossing.withoutaxisdistinctofnumbertotaltheandstates,symmetrictwoofdegeneracyaccidental
even.becomesstatessymmetricdisconnectedtopologicallytobelongmaypartnerssymmetrytheInterestingly
theofbranches I D−V DS asymmetricunpairedofexistencethefactinisItcharacteristic.ledhasthat27Fig.incurveouterconnected,singlythealongstates 23 discoverytheto
origin.thefromdisconnectedloop,theoftheofmapashows28Figure I C-V DS thetocorresponding, I D-V DS 27.Figs.inplot
sincestatedevicethedefinecompletelytheyTogether, I C = I S + I D ofslicesAlthough.I C-V DS givenaforspace V CS space,3Dtheinsymmetryistheresymmetric,notare
symmetrytheunderinvariantiscurrentcollectortheSince(1).Eq.byexpressedofplotstransformation, I C-V DS definedPoints28.Fig.cf.self-intersections,manyhave
thewithintersectionsingleaby V DS = 0 statessymmetrictocorrespondaxis( I C = 2 I D = 2 I S reflective,representintersectionscoincidenttwobydefinedpoints);
pairs.asymmetric
----
|-2.0
|-1.0
|0.0
|1.0
|2.0
|-0.4
|-0.3
|-0.2
|-0.1
|0.0
|0.1
VDS (Volts)
I D (
mA
/µm
)
VCS=1.50V
|-2.0
|-1.0
|0.0
|1.0
|2.0
|0.0
|0.1
|0.2
|0.3
|0.4
|0.5
|0.6
|0.7
|0.8
VDS (Volts)
I C (
mA
/µm
)
VCS=1.50V
27Fig. CHINTSingle: I D-V DS characteristicfor26Fig.from V CS = whichV1.50
componentself-intersectingabothcontainsloop.disconnectedaand
28Fig. CHINTSingle: I C-V DS characteristicfor V CS = thetocorrespondingV1.50 I D-V DS 27.Fig.in
have28,and27Figs.incurvesbyrepresentedthoselikemappings,spacePhasecloseinfinitesimallytheirself-intersections,ofvicinitytheinexceptthatpropertythe
vectorsstatecloseinfinitesimallytocorrespondpoints z ∈ R multidimensionaltheinspace R fieldstheall[i.e.devicetheofstatethedescribing, n (x ,y ), T e (x ,y ), ψ (x ,y ) etc.].,
aondistancefiniteabyseparatedpointstrue:alwaysisconverseThe (V , I ) planestatesdistinctmacroscopicallytocorrespond z pseudo-arclengththeinContinuation.
experimentalcontrast,Instate.devicetheofevolutionsmoothcompletelyaproducesinstanceforpoints,limitattransitionsabruptforcesimulations)MC(andmeasurements
k→u as22,Figs.in V DS orformationthetocorresponding0,fromincreasedisnegativeresultantThedomain.high-temperaturehigh-field,aofrepositioning I D at u
toduedrain,theofthatthanlowerisdomainelectronhottheinpotentialtheasarisesfield.collectorunscreenedthe
fororiginthefromstartedsimulationscontinuationofresultstheshows29Fig.V DS > 0 velocitysaturationhigherausing, vsat theBoth. V CS and V DS forthresholds
inpointslimitorfoldscausing IV withincrease vsat forreducedarethresholdsThe.smaller L CH inabovedescribedthosetosimilararedependenciesThese30.Fig.see,
transientaofspeedrampcriticalthewithconnection V CS inducetorequiredexcitationstablethe d atstate V DS = 0.
artificialsomewhattheofspiteIn v (F ) and T e(F ) canitsimulation,theinassumedRSTthepastobservedstepsnonlineartheofcausethethatconcludedsafelybe
Transientcontinuation.bypredictedfoldsandloopstheareexperimentsinthreshold29Fig.in(e.g.foldsthatindicateproceduresmeasurementtocorrespondingsimulations
for V CS = 3.0 transitionstatethewhereofPredictionslength.sometofollowedbecanV)dccompletefromaccuratelyextractedbecanoccurwill IV mustanalysisthisbutmaps,
circuitexternalaswellasterminalsallateffectsNDRofconsiderationincludeconfigurations.†
________________
ofcontinuitytheforbasisphysicaltheiswhatunderstandtointerestingverybewouldIt† W tot notedfootnotetheand13bFig.seecharacteristics,CHINTexperimentalintransitionsmanyatempirically
(6).Eq.below
----
|0.0
|1.0
|2.0
|3.0
|4.0
|-0.1
|0.0
|0.1
|0.2
|0.3
VDS (Volts)
I D (
mA
/µm
)
VCS=1.00V
VCS=2.00V
VCS=3.00V
VCS=4.00V
|0.0
|1.0
|2.0
|3.0
|-0.05
|0.00
|0.05
|0.10
|0.15
VDS (Volts)
I D (
mA
/µm
)
VCS=0.5V
VCS=1.0V
VCS=1.5V
VCS=2.0V
VCS=2.5V
VCS=3.0V
29Fig. CHINT: I D-V DS aascharacteristicsoffunction V CS (L CH = 5 µm, d B = 0.2 µm,
v sat = 2 × 107 cm⁄ onlyshownareResultss).thefor V DS > thefrominitiatedbranches0
origin.
30Fig. CHINT: I D-V DS aascharacteristicsoffunction V CS (L CH = 2 µm, d B = 0.2 µm,
v sat = 1 × 107 cm⁄ onlyshownareResultss).thefor V DS > thefrominitiatedbranches0
origin.
ResultsSimulationtheofSummary6.3
complicatedpossesstransistorsinjectionchargeThe – multiply-connectedoften –IV highsufficientlyaofApplicationcharacteristics. V DS fixedaat V CS > 0 aforces
domain.electronhotaofformationthebyaccompaniedtransition,switchingatoelectronsofratesupplyfinitethewhenformdomainsthePhysically, " spothot " is
fringingtheunscreendomainsdepletedThespot.thatfromfluxRSTthebyexceeded(field "normally" collectorbecomesRSTtheandelectrons)channelbyscreened
controlled.peculiartheironbasedbetolikelyaredevicesRSTofapplicationsPotential
inupshowssymmetrysameThepolarity.fieldheatingthetorespectwithsymmetrydeviceRSTmultiterminalaofStatesformation.domainhot-electrontheofanalysisthe
arebiasgeneralunder "adiabatically" theofstatesanomalousthetoconnectedatconfigurationsymmetric V D = 0 potentveryprovetolikelyisanalysissymmetryThe.
2b,Fig.ofgateORNANDtheassuchgeometry,complicatedmoreofdeviceswithisgroupsymmetrywhose C 3 v atoccurthatPhenomena. V DS = 0 essentialthecapture
general.indomainsRSTthewithassociatedphysicsmodeltransportausingoutcarriedbeenhaveabovedescribedsimulationsThe
mobilitydifferentialnegativeafromresultinginstabilitiesusualtheeliminateswhichverifiedbeenhaveresultsTheexcluded).artificiallybeenhaslatter(the 23 remainto
InGaAs.forappropriatemodelvelocity-fieldrealisticmoreawithvalidqualitatively2,Fig.inthoselikestructure,deviceRSTparticularaofsimulationquantitativeaFor
anomaliesnoveltheHowever,model.transportrealisticaneedclearlywouldoneinreproducedqualitativelybecan6,Sect.indiscussed any channelallowsthatmodel
flux.RSTtheincludesself-consistentlyandheatedbetoelectronsmethodscontinuationofusetheisanalysisabovetheoffeatureessentialAn
theSlicingspace.phasedevicefulltheofinspectiontheallowwhich I D (V D, V C) surfacedifferentat V C inresults I D (V D) evolvefieldsinternalThetopologies.differentofcurves
connectedaalongsmoothly I D (V D) aofapproachthesignalnotdoandtrajectoryoftypeglobalthegivesuccessfullymappingsPhase-spacetransition.switching
thetoasguessunerringangiveusuallytheyMoreover,information. stability givenaofunderstandingThesimulations.transientcostlierbysupportedsubsequentlystate,
thetotransistorsRSTofapplicationtheininvaluablebewillfashionthisingainedsystems.high-performanceofdesign
----
CONCLUSION7.
leight-emittingnovelofimplementationtheandprinciplethediscussedhaveWeindependentlybetweenhot-electronsoftransferreal-spacetheonbaseddevices,logic
thatdevice,logicmultiterminalmonolithicAlayers.complementarycontactedThedescribed.beenhasgate,ORNANDanaselectricallyandopticallybothfunctions
thebothexhibitsheterostructure,InGaAs/InAlAs/InGaAsaninimplementeddevice, ortheand nand outputtheeitherinterminals.inputthreetheoftwoanyoffunctions
arebutlayoutthebyfixednotarefunctionsThesepower.outputopticaltheorcurrent(thirdtheonvoltagethebyinterchangeable "control" controltheofChoiceterminal.)
powerfulsuchwithdevicelogicuniqueaisThisarbitrary.moreover,is,electrodecircuitaofcoursetheinreprogrammableelectricallyisfunctionitscapabilities;
operation.thansmallermuchisdiscontinuitybandvalencetheusedheterostructuretheIn
thetodueiscurrentnon-RSTparasitictheofmostandbandconductiontheinthatthefromholesofinjection p theintolayercollector-type n atoDueemitter.-type
activetheconfininglayerInAlAswide-gapawithstructurecollectordesignedspeciallyhighermuchiscollectortheincarriersminorityofefficiencyradiativethelayer,InGaAs
andnon-radiativerelativelycurrentleakagethemakesThisemitter.theinthatthantemperature.roomatperformancelogicopticaltheenhancessubstantially
atosimilarsource,light-emittingincoherentanisdevicedemonstratedThefrequencytheimproveandpoweroutputitsincreasetoorderInLED.conventional
opticalresonantainemissionstimulatedtheofadvantagetakemustweperformance,density,currentinjectionhighThecavity. J C >∼ kA25 ⁄cm2 devicepresenttheinobtained,
longconventionalinthattocomparableefficiency,radiativeinternalhighitsandtransferreal-spaceaofimplementationfuturetheforpromisingareLED’s,wavelength
laser.logicnonlinearcomplicatedashowdeviceslogicRSTtheoptically,andelectricallyBoth
ondependencesstateinternaltheininstabilities,novelofvarietyaincludingbehavior,usetotheoretical,andexperimentalbothrequired,isworkMuchvoltages.inputthe
functionalfastofimplementationtheforfashioncontrolledaininstabilitiesthesedevices.
ACKNOWLEDGEMENTS
Cho,Y.A.Capasso,F.Belenky,L.G.collaboratorsourthanktowishWetocontributionstheirforSivcoL.D.andPinto,R.M.Hutchinson,L.A.Garbinski,A.P.
here.reviewedworkthe
REFERENCES
Hendel,H.R.andGossard,C.A.Kastalsky,A.Luryi,S.1. " BasedTransistorInjectionChargeTransferHot-ElectronReal-Spaceon ", DevicesElectronTrans.IEEE ED-31 (1984).:832
Gribnikov,S.Z.2. " heterostructure,multilayerainconductivitydifferentialNegative " Fiz.Poluprovodn.Tekh. 6 [(1972):1380 Semicond.-Phys.Sov. 6 (1973)].:1204
MorkocH.Hess,K.3. , Streetman,G.B.andShichijo,H., " resistancedifferentialNegativetransfer,electronreal-spacethrough " Lett.Phys.Appl. 35 (1979).:469
Kastalsky,A.andLuryiS.4. " devicesinjectionelectronHot ", Microstr.Superlatt. 1 (1985).:389
Kastalsky,A.5. " devicestransferreal-spaceNovel " in, ElectronicsHigh-speed byed.,62-71.pp.1986)Berlin,(Springer-Verlag,BenekingH.andKallbackB.
Sivco,L.D.andCho,Y.A.Garbinski,A.P.Pinto,M.Mensz,P.Luryi,S.6. " injectionChargelogic", Lett.Phys.Appl. 57 (1990).:1787
----
Littlejohn,A.M.andKim,W.K.Tian,H.7. " logictransferreal-spaceheterojunctionNovelinvestigationmodel-basedastructures:transistor ", DevicesElectronTrans.IEEE ED-39:2189
(1992).
Sivco,L.D.andCho,Y.A.Mensz,M.P.8. " multiplierfrequencyinjectionCharge ", Appl.Lett.Phys. 61 (1992).:934
Pinto,R.M.andLuryiS.9. " indomainshot-electronofformationtheandsymmetryBrokentransistorstransferreal-space ", Lett.Rev.Phys. 67 (1991);:2351 " real-spacetheofSymmetry
transistorsinjectionchargeinstatescollector-controlledandtransfer ", Tech.Sci.Semicond.7 (1992).:B520
Luryi,S.10. " circuitslogicandtransistorsinjectionCharge ", Microstr.Superlatt. 8 (1990).:395
Luryi,Serge11. " electronshotofreal-space-transfertheonbaseddevicesemittingLight ", Appl.Lett.Phys. 58 (1991).:1727
Cho,Y.A.andSivco,L.D.Hutchinson,L.A.Luryi,S.Capasso,F.Mastrapasqua,M.12." withtransistorinjectionchargeemittingLight p collector-type ", Lett.Phys.Appl. 60:2415(1992).
Cho,Y.A.andSivco,L.D.Hutchinson,L.A.Capasso,F.Luryi,S.Mastrapasqua,M.13." propertiesopticalandelectricaltransfer:real-spaceonbasedtransistoremittingLight " To,
inappear Dev.Electr.Trans.IEEE 1993).(February,
Cho,Y.A.andSivco,L.D.Garbinski,A.P.Belenky,L.G.Luryi,S.Mastrapasqua,M.14." andORbetweenreprogrammableelectricallydevicelogicemittinglightMulti-terminal
functionsNAND " 1992-IEDM, DigestTech. tosubmittedand(1992) Dev.Electr.Trans.IEEE .
Ren,F.andSivco,L.D.Cho,Y.A.Luryi,S.Mensz,M.P.15. " three-intransferspaceRealdevicesheterostructureInGaAs/InAlAs/InGaAsterminal ", Lett.Phys.Appl. 56 (1990).:2563
Luryi,S.andSivco,L.D.Cho,Y.A.Garbinski,A.P.Mensz,M.P.16. " transconductanceHighthree-terminalinconductancedifferentialnegativeofratiopeak-to-valleylargeand
devicestransferreal-spaceInGaAs/InAlAs ", Lett.Phys.Appl. 57 (1990).:2558
Cho,Y.A.andAlavi,K.Wecht,K.People,R.17. " conduction-bandtheofMeasurementIngrownepitaxialbeammolecularofdiscontinuity 0.52Al0.48As⁄In0.53Ga0.47As N -n
byheterojunction C -V profiling", Lett.Phys.Appl. 43 (1983).:118
Dutta,K.N.andAgrawalP.G.18. LasersSemiconductorLong-wavelength Nostrand(Van,1986).YorkNewReinhold,
Luryi,S.19. " transistorsHot-electron " in, DevicesSemiconductorHigh-Speed Ed.Sze,M.S.,7.Chap.1990)York,New(Wiley-Interscience,
Shah,J.andKashK.20. " IninrelaxationenergyCarrier 0.53Ga0.47 fromdeterminedAsstudiesluminescencepicosecond ", Lett.Phys.Appl. 45 (1984).:401
Coleman,J.J.andEmanuel,M.Higman,T.Hess,K.Kizilyalli,C.I.21. " CarloMonteEnsembledevices(NERFET/CHINT)transferspacerealofsimulation ", Electron.Solid-St. 31:355
(1988).
Hess,K.andKizillyalliC.I.22. " TransistorsTransferReal-SpaceofPhysics ", Phys.Appl.J.65 (1989).:2005
Luryi,S.andPintoR.M.23. " characteristicscurrent-voltageconnectedmultiplyofSimulationtransistorsinjectionchargein " 1991-IEDM, DigestTech. (1991).507-510pp.,
Luryi,S.andSivco,L.D.Cho,Y.A.Garbinski,A.P.Schumacher,H.Mensz,M.P.24." transistorsinjectionchargeofoperationMicrowave " 1990-IEDM, DigestTech. 323-326pp.,(1990).
Fischer-Colbrie,A.andMoll,N.Hueschen,R.M.25. " inperformancemicrowaveImprovedtransferelectronreal-spaceonbasedtransistors ", Lett.Phys.Appl. 57 (1990).:386
Mizutani,T.andMaezawaK.26. " transistor-charge-injectionofcharacteristicsHigh-frequencyfield-effectmetal-insulator-semiconductorAlGaAs/InGaAs/GaAsinoperationmode
transistors", Phys.Appl.J.Jpn. 30 (1991).:1190
----
Hamm,A.R.Cho,Y.A.Mastrapasqua,M.Luryi,S.Garbinski,A.P.Belenky,L.G.27.Smith,R.P.andSivco,L.D.Laskowski,J.E.Hayes,R.T. " light-emittingCollector-up
n-InGaAs/InP/p-InGaAsandn-InGaAs/InAlAs/p-InGaAsintransistorsinjectionchargeHeterostructures" tosubmitted, Phys.Appl.J. (1992).
Pinto,R.M.28. " EffectsDeviceULSIofSimulation " in, TechnologyandScienceULSI1991 J.,eds.,Cellar,K.G.andAndrews Proc.Soc.Electrochem. 91-11 (1991).
Stratton,R.29. " barrierssemiconductorinelectronscoldandhotofDiffusion ", Rev.Phys.126 (1962).:2002
BlK.30. ∅tekjaer, " semiconductorstwo-valleyinelectronsforequationsTransport ", Trans.IEEEDev.Electron ED-17 (1970).:38
Pinto,M.andLuryiS.31. " transistorsinjectionchargeinstatesCollector-controlled " in, PhysicsDevicesOptoelectronicofSimulationand Yevick,D.byed., SPIEProc. 1679 (1992).54-65pp.,
Thomas,E.R.andCaugheyM.D.32. " torelatedempiricallysiliconinmobilitiesCarrierfieldanddoping ", IEEEProc. 55 (1967).:2192
Wordeman,R.M.andBaccaraniG.33. " inovershootvelocitysteady-stateofinvestigationAnsilicon", Electron.Solid-St. 28 (1985).:407
Smith,K.R.Pinto,R.M.Jr.,Coughran,M.W.34. " semiconductorinmethodsContinuationsimulationdevice ", Math.Appl.andComp.J. 26 (1989).:47
