Voicu, Dolocan - Fizica jonctiunilor cu semiconductoare

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lucrului de ieqire pentlrr rrnirl din metalele folosite, clin aceste curbe se pot il

detelmina lucrrrrile de ieqirc tlin celelalte rnetale. Bariera de potenlitr,i n-rt
rnetal-oxicl qtlo se poate determina clin rrrrisupi-Ltori de efect fotoelectric.
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A-sa clrin se clbservii in figura 5.12. r':i,clircina, r:ubicri clin curentrrl fotrtr"leltric

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I loloi'irslirnsuiui iir ;i:lr!it:
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in func{,ie tle energi:r fotonilor estc o dlea,plir, c:nle interseci.eilzli, axa rjnr..i'giei
la rraloarea, gCIr. Addugind Lr, qO,,, a,firita,tea, clectlonirii :l oxidulni, qX,,
se gti,se;te \-aloii,r'€)a, lrrcrului cle ieqirc din rnetai, q0-,. Depl:r,si,rilc dlr:ptcior
dirr ligura 5.12 coilcicl cu ileplasririie cur''helor clirr fip;ura,5.11. Penlru *
g'risi dia'gra'ma tle benzi r1e energie la interfat:l, siliciu-liioric1 t1c silici'ir s-rlr1
folosit, cle asenicnea, ru':"rsirl[ioli t1e efec1, fotoelectric inleln l4l. Plol:l,
folosit5 esl,e un ctt,'p:l,r:itot'MOS cu strilluL C.e cixitl intcrltraia,i, intre trli"tir.lnl
cle siiiciu q;i tln electrotl mctalic, sul;tire..qernitra,nspa,i'errt (fig.5. L;it.
frulilin:l ultm"violetzi tl'cce plin clectroclu.]- ruetalic si prin sti'a''tul rle lrio,ricl
de siiiciu qi esrte ptrternic absorhitir, in clist:llui tle siliciu. Itotool:r:trtirrii
exc,itali din bancta dc va,1erL15:l silicirilui trec in ]:a,ntla, c1c llonrluciir, :t
oxiclrrlrri. Da,cri silici*l este de tip rr, qi este degeneui,t, llointo ilyea 1{)c' {'r{ci-
tzlrea, electionilol clin ba,nrla de r:onthtrt,it' a
sitriciuirri in hrr,nrl:r, rle r:onduc{,ie a o-xiclrrhLi. i?5,-
Lumind
$it,ci1t3, p['tratI a rtspnusnlui ft-.tc'electi'ir' ,Ii in
"1uv
i 1ws*W,'/eicJF)nergi:l,'c*l?ep,:ra$g:e'fsf;telue-gla;"l5f,fci*u*t1l ifie1rle;in*i',?:l3r11ijr.:r,t,r,i;l:ff:
+I 'Il vj s.,r^u' liautLa th'r-nlenli ri' siliciLr liii ,..i Iratrd:l tli't'on-
rl77-/-l77nTn ,lueiic a bio-rirluliri rk. silicirr i',r,'" s-ir, p:isii a
si aLvueiiaxl_ri'nalocaornesaiit_reinrajrucr cle, 4,3, enr- (fig. 5'b.eia4z)iil5inl-.

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rt|r':r ct.ficcincr.clrsrsilllilicittiucfotiluo' e.6l..icolrxilici figura 5.15 i6]. Anaiizind aceastS, figrrrti ne
irrrern

dd,rn seama de ce sistemul Si-SiOz este tel
ma,i mnit utilizat in realizarea tranzistoarelor cu efect d.e cirnp de
supr.ifzr,!5,. I)eoarece minirnul benzii cle icnonac,lpuroolipeie,srei ma naxijilroncunl lbueinbzeiindzeii

vaieni,5, ale siliciulu.i sint localiza,te

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curentul fotoelectric -€ in funclie cle tensinnea y aplicat*, folosincl pentlu
excitare luminir, monocromaticd,. Forma curbelor diferi cind energia foto-
nilor este mai mic5, in comparalie cu ca,zul cind. aceasta este rnai rnare decit
1n5,1!imea barierei in absenla unei tensiuni aplicate
n Si- s;02
hr=5eV clin exterior (fg. it.77). Reamintim c5, sc5derea

ind,lfimii barierei este clatd, cle relalia cunoscutS,
din capitolul anterior

: -AeIl (q6le1trz,

r'. v unde constanta, dieleetricil reiatirrX pentlu bioxidul
de siliciu se ia in acest c?l,z egald, crr 2,15, a5a curn
F-ig. a5p.1li7c.at-e Efectui ten- reiese din comparalia cu datele experimentale' osi
siunii nu cu 3,8, valoare care se g[seqte itr motl o}:iqnuit
asupra curen- la frecvenle jo:r,se.
tuiui fotoelectric.

5.3. Efeetele ea-pesainlieetiruo-rb;ioi xsiralredienilsoirlicfiiuxe tle la inferfa]a

A. }Tat'uru coItcr'nel'or ;'i st'rcinilor fi:ne t'le ta interfald'

Caracteristicile strlcturii IIOS sint afectate de ci,tre capcanele ;i
nsioaenrloiczrianqtileiesdfaiixnrceisntcirllaoetrluaflixdineetedoerxfiadla.f[iinnl]tIeearccfauelnsdtr,.p;aEi,rxdaeigsract[,if,tevrleooumdio' nttliipisi ncmuriotaid'reeilfice'ec;intetc'lraeepc{*iaac'pnticevalee-
tocalizate la interfata Si-SiO, care pot afecta performanlele 1i stabitritatea'
stmcturilor IIOS. Aeestea sinl capcanele cle la interfafi, gi sareinile fixe [8].
Dod.ceeuolpaseaitrnreitreaerafsa!ain,5itc,rienseielomlerocfroilxinfiseetSdr,,Sci,nmu fimanepotdnuietfisccca5h,leiomacublpa,eat5nre,s.aiuPnceuiinedtrleeucproatraorvnt5ei ,da,,ecianapotcirraingnipenleocare
captanelor i1e interfald, qi sarciniior fixe sti, consideri,m un crlista,l de siliciu
zcdaleivhtiaeistnuinbstt,vrialcetlgucdlletcu-laerillleuanliognruteldru.fiann.utarifiapsrdlian, ntrdlc,errngisiantlaiinlotnlgunrmaefasicai.tcilAseftiaoctumotmeii,icialedsti.fnqeilliscctiruiattrnriot'crceacqlliet-i
atomi nu'mali sint supugi aceloraqi forle ca in cazul cintl :i,r'eau toate legi,-
turile satisftic,ute.,Pentrrr ca energia de la' suprafatti s5, atinp$, o vp,loare
minim5,, atomii cle ia suprafa{d, se vor deirLtsa din poziliile lor anterioare
elsipaliivlna,thjlunlsusuiitpiqciailuafacrl.ea'oarssetei,rmispitecaorfmntud.abuxcaimtloiemd.clououin.delsl,utuicrie.nridl.apeiannptrcauorinfliiseaiec_.luaerrneaoraer togd,mero-qpceil_ecnlleae,rapslouebaperdane--
ti,1X. SUrile cuantiee clin bancla interzisd, a siliciului se nulnesc std,ri de
se afld, la, intel'fafa silicin-vid. i3 Proeesul de oxid-are
inierfa,!,ri, cleoarece elc
auinstiotdemerfinlaoslirdta,rtleqeaissildiacericusindtSielerliaf,ti1xseueplaraa,ipfnaa!t5er,rdf^aasttinoi,tridstdaet,vi"isdnfeed,-fceeugctetael5dloe,cr uclXaz,terinerotae' ,rtCfoaarnlpai-i
Ieg5tur.iJ.e

de"oxigen
canele*cle
Sdaei-sSiIlaiiOciiznu.tleuCriafa6pfacirra,encepaioeretdcaearpiintnateivreefallee!c5te,rnoseninrigtqenitigivcoeell,uesriite.tnraSStaregrecintiniciaelepdrfo"iirrpreielrrpaeonadt amfi aincritlgepiclnzaiilnsoeili
benzilor sau pot fi loealizate adinc ln oxid astfel ci, nu-'1i p_ot modifica sta-
rea de incS,rcbre cu varialia tensiunii aplicate. Regiunea de interfalir' este
regirrnea in care are loc trecerea cte la siliciu cristalin, la bioxidul t1e silicirr
ariorf. Aceastd, regiune cle tranzilie are o grosime tle doui,-trei strate ato-

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B. f,Ietocle eirpetim,enktle de detertni,nare a densitdlit ca,ltcanelor tle

interfa!d,

l)etenninarea, elensit5,fii capcanelar de interfafir, se frt,ce plirr rnir,su-
rare-a cap_acitS,tii qi concluctanlei stru.cturii MOS, & c5rol vi-r,loare ln condi-
lii date clepinde cle sarcina localizat5 pe capcane. fn prezen!,a capcanelor
cle interfatd, cir:cuitul echivalent
. i. din figura 5.9 se rnoclificf qi cap5t5

-iu] -r-., forrna clin figurr,r, it.79 a, unde C"
;i R. sint ca,p:r,citir,1 ea, ;i, r'elpectir',
:-",+lrI-.,,."ftf"","., "_":,'dTrILt-' t
L --ilj rezisten!:r, asocia,ie czl,pcanelol de
L--l tf,oo.lr"Lt
ini erf:ltii. Cixruitul cchivir,lerrI dilt
fignra it.79 a se poa,te Teplczenta
ca in figula 5.11} Ii, unc{e

c) b) (',-, - C r, :,- I '', - -, i,,.10)

cu:Te

l'i,q. 5.19. - Ci:cuii.ui ccbilalcnt al stnrc- -(]', _!-":r1__ {5.10',)
lrri'ii 1l(-) S. I
c,) J. i b'1-

Cu ,,'riG, tlepind tle frecvenla, cle ltrc,rt ial T : {,r"f?" sie l1ul}ltlste cL}l}st':!nti'},

de timp asor:iat5, cri,pcir,nelor cle interfa{,X. --!dmii:i,n!ii, circuitn}rri tlin figrlla
.5.19 b este

I .G;ioC; G otttr: ":Ci ' {i'u)
( f.io

g f'-. [1.', - ,,. (Co -i- C,, :- (1,)2 r- c'r?-'{lr'(Co -1'- C,,)
--C--o{'-!c-r. ([in -.- Cn -t,- {',)2 1 cl:::( (-ro -:- 0"):
L

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t n-6 pI ucutncor il(o{',pllrroXb{liiar1.l,:lrtpiptrIi7--r
1:i!ilor acceptoau: !.08 .
I . 1016cnr-3 si tli:nsit.atca
rle jicral IJiclat'rlc10l1arc.inrrlief\r'l-'a1!.i
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d | ,,0,,

I
I

ar.IbIce-"-lEinnrlu.'JipTi-ir.iqrr,IuuI,ilnl'nr3)u4lsip,llrtIaJul1nursl11uonclauatcr1usKJo.p"ulzaoror+rua;,a1+ioye-.ulJ;turr;..1pxrpltrrra,x4+uUrlsala.Iurlrgiraparlesq,am1u.fir€ruD,rlJodi'uautural1as1u:l1nn1?uu€uJJ*Ia'cnu1cncr;lansrrts;gJ1rl1slre'ol'r;1rou?piinrrap:a't;IuoIgcsaruop,'dD.eurulrcrItnrcrIursiIDrosu/linIuaouot.I\ulCorpdrpr-r.il_p.'ulIrSocr:rdJlg,;l'pansrirrpriln'Ts1ruuopJF,'1uuo.urux;paa1]-lllp{u'1Iteo1s9pJul1aauleE+C.su;crocatoIyiac'unllull{ucpq}+'zt'a3(1oB'uncdau''q1]3a+pr.p'lio'lro0trl-ulrI,sup-'ilan{u'uoe,1ucguIlsIal'Llo{Tuainriuer)u/loTu{'+pt6ura,I'up(rl.r'6llpe"r'0'rnJrueCa;a'a1oc9cI:nlc''sdie-.J9luix'pua't1Io1)etua4)!l4lparl.+olgtarrr*rlsd}1uul'o"u+gr(1i1apyr€u,o7.i.lpa10ttrs?-clllotnu;e1aiI?;.nua1nrdn,1;eazr:ntntpu})saa1aausprl.eur)gue1prliuirrxu{i'to{n.ioZu:otrlra1+ri.ldrullarunp6eu'splsD1.uuc'nur9.1aat1rgTlaS1eoneldlzutaorlpYl',a'(;1Jsplte'rYurpluuraancp'r"l.uFiolrrtrf:n'nloxeioc+s!idtuDSdt3+;dla3ldruuep{lIuurrasr-uIp+oulp1r;,{tir

ap alunrl 0 nt olgulrf,{,Ia+ Tnop a{oJ ol]ul UJIIJJILT+g u}1I'B+IuIpr1 gJBosEIu aS

",LrzUoti1.rn rrinc gclnp ezrelroao,rd aS Ii]]LIU]OIIpuoJ €a"I€JnS"Id{ rLI+IIad

reluulcnpuoa €pogaIt'I

,u-a'Xf"t1r6if,piafiC'nr.g1rIin,oOceesl1_Ou,1rralnnlif.spzf'-re'iefiorr$r;op;pa2na71e1us1rd11isrr:ia,i1eiituaqp9,aruodu{a(auanl,lsuo1,oucu,tictlrliaaopsol;auuJpaa,erarspslypocnn+rBcanpslincuafrrouilonouipuacrlaldlca,?drurnl*os.'purlaare;u;er.rciocYlT,uot?rncyc'uo(lclursulpe-aa(rqd.1aur't_uca{sIou..1)rallrnu€{u-sqal?rcpiu1,lqunisnua€1up:loalouuUrrea+ogIcezGtl)apecrErhd'ap'Egulof-.1'rgaeiJLu1rrpd;I{+.Iolycrrrx;.reurr€Ic.Slntuusl1t;srta1IueupeolI1J€uIrpapu,n;'irSrlrJrt[rog-o.9O{rileol1eolIp{g{]lrt

-t;dl:a trdnse a,l€ITL{rIS rriuuuo;rir ruiuo;; C iij +It e +l'}l? pf, lruasQo a$

orientate dupf d.ireclia (111). Punctele din jumd,tatea inferioar5, a benzii

}ian--ut.erdr:ziaism2e'0es8trnu'tl1rde0ez1u16lt,ca2mte.-l13e0,m-(18Xc,srun-.r5PP,tuo)nrlkiclotfer l:epedLsin4tmtjLucm,tudCr,ataotIe:IOa5S1sr7r4cpeu'ri1So0air-d58.,eFat/icpbmep2nczquiii

TIP N bt TIP P

J UM AT AT E,A {t{J tNJUrttR'1AtraAaTnEAA
{o()
supentat,nA
AEg

. (r_qN*r

Iris. 5.22.-}u in lLtuclic al.rf;;; ii:i., pcntm acclt'asi probc. ca iu

interzi,se ,scYilni7at,m:le1ez,t1urul5tla'd1tee0le13,68rn.dc,1ms0u--r23titc,omr(iFlo(rF- peeEstes)ltklpuoTczt:uiIlr3iaa,5n1\i,IvOeSluCcluuoi:s5Fili1ec0irum8. di'eg1i0tiH-p8,

w1 c1r

tri/crnz ;i
este rnijlocul benzii interzise). Punctele din figurile .5.21 qi 5.22 corespu_nd"
maxiurelor lui Gr/<o oblinute din md,suritori la 300 K. l\{en!ion5,m cX rela-
tiile (5.10) au fost scrise iar circuitul echivalent cle mai sus a fost reprezen-
tat in plesupunelea existenlei unui singul nivel c1e energie al capcanelor de
iriterfritu. in realitate figura 5.22 aratd, cL aceste st5,ri stnt distribuite con-
tinUu in ba,nda interzisi,. Se observS, cf, densitatea de capcane de intcrfali',
energia qi in apropierea centrului benzii inter-
-r1-r" ,avstliLliic:ri,uzil,ufioeasrtteeinskjlubr cu 1011cm-2eV-1. De$i capcanele t1e interfa!5, sint
S{air-yS-aiOgsu.ryLarerdcesnesditiantefaigutlera1502uc2m),:2toeYlg*l1l
zise cte

ii,propia,te energetic unele de altele
cle sfnt distanlate spalial in planul

rlpcauel-e cle int'erfalti, se afld, situate unele fa!5, de altele la o iiistanfd, medie
tle^300 1, astfel c5,'nu este posibil ca lungimea do unc15 a unui electron
Xtngb::lrlioole,vCprlceuntntallil\intcl'l:,olie,p,gpreatoeilplu:ltrnuu,nptrslriculuno.epurnCrs,tanperdufmo;aeitlisaccCXsoi5,tsn,,r,sedeaaimniucbtoccdicatpp,ooperlroconrueacbdl n".uace1uCcbe.ttiototlniintrpc"Xusegtlnlniuai'lptnie;t"'itucasd1!ieeand:dtct,ieipaacTcptoilentmCnuncorsptei?,ir,;,rriartpretsareeseal_lpieinnpleectzocmtritaleotisitslnlee,eeiclm?ostdrrcicoero,qnienliia'ldocrureuc:s;n--i

:??, f[d erp (qr!,/tuf ) : n,**p [-ilr{ (r.1," - ,1,")] ; (5.12)

p,: Noexp (- qt!,lkT):'n; exp l- *(,1," - +")] ,

?58

{;91

{rls)
f * :'(#)p
(ua)F+ owt(/i -t z)-io""*_t io)rzl"irD ('+)oc dc

"n-L(Eo

(slE)

: ,(#)p * -(oza r)ur [(r :)-r o'" :t ,n-l(2o -.i- io)'z]'-,rr u 1 *f

-srl-€]o. rar{nqr.l1srp roiJp's{cuoyr.Jroq1ugi SaopunJorasIruuraTr{?+qsoaJ€atoosanr'mJ;ro+np'ur1uoulcaa;cprullisrinnleqnpl.(oquJso+lps?so1rloan4zl€:)Dearcu;{r€Il
'rLrDnI ap riuaaca.rJ

'(q) glerlr]Idurls rls ua.nlluoz 'soJ\ E.mlJnJl.s uI
-rrdar : (D) PiE.Iralul ul ai) rol-rlrlJ.rus E grrJsllrils l1inc1J.t1s1g - '82'S 'o'tC
lnrlrres e1t1iun1en1; ;)p ElBt{
-.rrrrrJlap dru11 cir laluE:l.suot
ursladsJp g]€.rB cJuJ 'lui'IEA
-nl3a 1n1n1r.rr3 - '1.2'q 't-!.{

(q

(-)dc (m)dt

rrq$a,ur{nouu.urr,lttrrsurrilrpoaleJstascucTopardaa1ri.1qasb,rr.uruaul1ncu€ur.rIns€aDa;udIIxeJ.Ip?,4I'1oo4.rrJ.p3+.alsaJlr,;r1om4+crp{€nzJqetusacquuororlJiacurrptnouJul.rnSpool41pucurn$adQmsoJ{..\qr{oo?c.oml(^"o}aTll?n:.'}r"9}[1r)'
fr;rluecd ,76.9 bTn5rg u; n1duo,{a ap grluaza,rde,r a+sa runc tSe 'pclglpout as
,lual€arrl)a In+rnc"nC .pbrlsr.raqcu.r,E? al.r,l] alSarunu aS €+S€acE : ruJoJlun olso
1:"oi1uu;a:riuabriroucfa- pa;eru1cu;ur1g!aoiouprurErrurrrnuutsuoltJ-.ruJruJ,lerop1{eu1yzlaol.urdrai.nr t1rutl;dt1gudrPozJIt^sTcaprJalE?€c+1I}ouJr+3stt

n,'-'nrsr:.r1]as.,rr,luonuunalltl,ci1aolunc1l'tnnu?,ugeorl;trbcruluillcrrrnutlu"l3[rto,rrurro1{unulsoltnncpp;lncr1gn-;1url}utoas'qg4,i\sucr'rpnpir;{ur{lum1uJcg;at?a.,r+rr1oc1oa1Ispnqrsnu".i1,4eYr,n:yIIIcu_naf1,tIiupcnol1lncanlss1Feuu€ipc1IIo{lruucJieIa€-Jlrns+olccfl.oulapInnacoll1gclrunun'daal\Jt.uurZun?ic'odJSlnp(Kusz'+rfau:tIrnnoyldz_d)ayspJl1uecna.s'rauinceugsll

t1-l-:iundisi,i'oa,iTbF-a"lu+ip,rort;'a;anrug.oirri1+oisirtqaurcub;ooorrn.dtrrix1e.-ac'Os(g6%.g1tiu0a;rIrr/gt:Ze:rU,'(p'(rZ)?n;.rrr14nra:,1rt+q,'g:-dqn"]ui;n4lgrC'CE'.l1rtel)lJupn:.ere+er41-obdspa'oortuiuepitn".l*crCJ'i4lc.aojr,ToI;lIrtdJstpco:rgn+opKrIu'-r."1gguI.rofr1ondu'dI(u€e4,;duta'q1TucxE{e_to7Diodl1IoIsIt(I9raJ1efla.u"6sr+C'')9staali:li1gpeo:"q'"ruutnorittCfptnllJzT(*l',atr+q,o+:gl:Ig^'Ibr'

tlndc I

I : Into;; = = {_, (+, - +")'/12(of f of )1, l:

i.rqnp$uirgitSo.,tliil.oltr abaterile standrllrl ale sarcinilor de supr:r,fafzi si, respectiv, ei
acceptoare, rlate de r.elaliile
:.
"": r,.(,,,;l+(+),", (5.15)
:
6t, - e2(N.lilr|rrzfl - exp( -q ,l,lkT)l (5.16 )
rl
2h?(coli.. -j- e,)
:
?n relafiiic_tle rlai sus s-i111 lua,t in consitlet'are fhlctual;iile potenlialului t1e
srLprafalti clatoriti distribuliei aleatorii a,tit a sarcinilor de'la inicrfatil
cit
5i a impuritd!'ilor tlcceptoa,re. 0 este densitatea rnetlie a sarcinilor dt-.la inter-
{tao{riri.l,orr.fi"o.-npizoatlig, nIlll'l-ul sintrteartfu:rlutiii,'c, lef,.'cle-flerlxeinesi$taiteaa-rneadriiea
merliu la a acoep-
risticri . lilrgirnca, carzlcte-

2. l{etodir, crapacit:r,n,tei

f;toaipailr.iricrrllc'isrr'-c.raslfnioacilu,o,'rssinauexsrtsieclormeatlriepldei,crpcaaarptopracracleiciittiiiel1,,l1eai3it_1ec:.laePplcraroliecntienecndalneifletuinilr:e-prfrnrree{in,ciaevdledeinfeet1nir1rs,e1i1tnqi,iii,iftllirriaeinsftc"iieoi,nrnc,tsi.ei.oteXgrni.dtianierr,elirjnoizlnt1re,ds2r:-ill
tn^funriie _dc tensiune|.-anlicatx pe structur[. A,sa oum'se observfl, in iigura
d.ouii crrrbe cliferi, intre ele. Deoscbirea aprr,re deoalece la'frecrtnter
5.25r celc

eitcrrulhal',.iat'lr(pira.1e6ii)rrsleeilrrenc_luucrelc1p*inedccudaetiasu1psl..{r};f.l,qbrf-ie. cintutrl-asdtirerril-oJrr,cIlieinnttetrlfaotXr.>s'ci
mCa:nif.ef(sVt5),, plintr-o deplasare a
curbei
cle 1:r, cur,ba idealii,
cu ATr
de-a lungul a,rei tensiunilor. Aceasta se
intimpli, pentni ci, prezen!:l capcarrelor
interfalf cletcrminX un
Fr tc vonld cle oxirl mai rnale decit cimp electr,ic

in la suprafala
semiconcluctorrrlui, ceea ce face si, fie
ner..csali, u sa,r'cinii mai rrrar.c pe rnctlll
pentnr a obline un cimp dat la supra-
V fala semiconcluctorului. Cum starea de
detIrrnjEsi.iu5n.2ci1i.n-
DcprlrLcn!a capacitdlii tie incXrcare a, capcanelor interf*tti

slluctur.a floS cn scmicorr- depinrle c1e tensiirriea 1'- aplicatil, atrrnci
7.tlrrctor
clc tip 1). la ire cven,te inall-c ;i la ryi deplasarea AZ va fi funclie de Din
flccvtruir joasc. compararea culbei consider,ate cu cnrba

:Ig).\IfS icleaki se traseazX graficul Atr
:Sa,rcirra..pe ca_pcanele c1e interfa.td Q" CoLtrr si densitaiea capcaneloi Ae
intellalir, se ob!,ineprindifer.en{,ier.e graficii,: ,}Iu":(1lq)@e]a*l),.. stiliicm2
e1-. Procedeul de variatie a temperatrrrii se baztazi"t, pe motl"ificaiea st5,rii de
inciirca,re a capcanelor cu varialia temperatur.ii. in figur.a 5.26 in semicon-
r-luctorul de tip p (und.e st5,rile de interfali sint clonoare) la o temperatrrri
?t se presupune ct"t sti,rile sint neutle a,clicii sint ocupate cu clcctrojti (niyc-

1,60

IOI

0t9 "o -Il

ua--udsioot(ps1oon(1prTn€r1f{pcIrg)pr1ou1uosfuuc1€y.urr'd(l.zrrfd+*qIunTi1rscae) du'ar0or_'q_pfau.Idugcu.uer.lSdrgedlfplunfnso1opz.€nrno"+prd.tnrsoe[nc,mufls"qunruolIu+or.seoLxa8lJrotJgsrrtxplslnuropuyirqco1xro{teqCspuos"r10;oErr0"dxpr6rnJr1e1Su+€.a;luargar+lcucdrrsprtluuLsresaxclposaiSnpoo(€rpgotodar+aieFr€mirqalirooipsl
q igfl -o--r-r;r.+r"reoisad+daaseqor,rr;aonFplu+€aes'uasdcrleu,rtroJscr"nsrpreodno,puiueurgooeu?+r8;*srrr€odxgocnos€Js)nopopu+orce+.€rr.uudrzrarr{l.p€u"rr4co1orrnyerl1o.ter.uruolopeld!prouxod.ourx-frIoauJpxoorp.Jlrlu-oJuoiorl(dcrOlirorr€wpOpsucf)o1eK.3curcrsrfqq{uudrlrayzsec;rpoyt.g€5rdduecnunrplsrJ-ssgr:pu;?re.ou6aglwq1sg9ue'u-ocl(1.gdru.9idaglinei-leaqu{Frdiursorfi
r-tusrcurpuGscra€a{a.Igtseo.rl€dauslsts{arrtrsr+)rraerfJuogua;pdnespmn.dr?eupodoxoJr;tsJtuolrrm€ucr;r€uas }m€aler€qoldl€uaaCpi u(1tld,in1

acBJ oc uaoa re,.rrlrzod_'uuudn.ur+eapp?oo+TJaK+ssacroruxrraJ+Jo?ltrsuIrrcrx"rousInIunoIoqUeIslr"erq{uoJjre(gdns rc

IFinISuo+ ntss rrJn?ts.radrri,al u{uengur qns sz€as€1dap es ,ro nrrrffi;f";:
er{r.ruclu nrc,uad eirqusuodsa.r oglloeJc?rlrcrolep:€oopuqnormsura+gue;sp-orxiry.roagpcunrpcujouogru1ro6s'

: rq.reod od {np

rolrzuaci Barruqcu"r ap_f?uapuodep1i1 o-+so mo.t+colo nc rol ua"rudnc6 (1
: [tf] iif+or.rdo;d oloJt?o+truun nu oxrJ olrmcr€g

pfn{ngu,r apt rclauncdnc * an{ rolxurctns alcfpgautdat7 .g

$li :'f .blft - :-aaa-.erpluoegur+dl{nwnq*zco?eCol,reIejg+last+rF'r(I.pgS"r?lqpu+pggs.ul;l'rgeAlatldc?gotur)prrru.rgolrugcpslcsaj.suruorualor+sfuwu-u.I;nSrcucd*^KstnS:cncrO+sp,ctesrIot{os4arl'urper?l"r,rospmepupo+oqoerd(nre;Jrargcncs1cnutn;c;i1.erpdlquu8"erood9lgui,auo.e4jey-1r)4r46"rr1rur{.erni'le,1is,-Tfo,ref?,nrruutc3iglsilg-i,;r1gol*u{rlr11ia*p.t:lri
?pu€q op_rrunlsuel erlur.re1 '"1; p,iugr;rdns ap plurriuelod op "$ pr!?y;reriir ep
pqilrruic.rus efuapuodop III o+tsp olsoc€ csolJeruoa os is p.nqueeourel aii eficuq ur
gpueq_aB €a_ulqs{ra? Ez?ar+sr8olq es i s;rnlxsqs ed aluallde iiurLrsirei
op ur$rpuoc onrfueur as r* e;lngu.raduiat g"ur.r,,:,r as
ei{tar.ru,t ut,itl plqd ppuuq

'sol\i llrlll .n.rn1u.rocI
-lnr1s lrielteudec e u.m1u,rad
-rlrll 11r urirr.rull - 'Ie'g '3IC --.trultarl.rnl JJpgluil.rIlta?ll's.riEcripE]..rroirle^rr-erc.{gei;.:u, ..uijir:It

1\ j
3
ti1\ ,
,tl\ \

I,l, '\

II \,.\'***-

Y

Qil{: ?lt:-uscIau^aJloaa+dssKE,ztrtKtrsrlzloo€praeearpIcrgrac,olta.f.orr$u>oosp4CI,o€7Ig€rJa.quEno+rnnsulercmr.rrteapadd_teuxvg1rle.vrl-u(gd1oC6o,.u9rr."1^&.I'F^+(;etrItofz)u1oodiuu"-rotqdl3n€psscuqrteKs,rpBcnuucKElIeqJup€araappsfeeapIgrndrruoSJso.erffilrrtdroeIenrpslI

6) Densitatca sarcinilor fixe este pra,ctic intlependent5 ;i tipul impu-

ritililor din siliciu.
7) Densitatea, sarcinilor fixe este inciepeudentd, de grosimea stlat'ului
cle SiO, pentlu anumite cond.ilii cie pleparare, adicX' este indeponclenti
11e tirupul cle oxiclare.
8) Proplietd,tile gi controlui sarcinilor fixe so ba,zeazir, pe clate cmpirice.
Natura chimicti a centrelor cale dilu sti,t'cini fixe nu esie runoscrii-l cri c-.::lcti-
tate qi nici leg5,tura dintre a,cestcrr, ;i capca,nelc cle irrterfati-f .

Capcanele de interfalit au urmii,toarele c1ouil proplietil{i, c:r,l r, 111'tor'-
min5, influenla, lor asllpla oarariter.'isticilor disl;ozilir.eior': deusilrltel loi'
este funclie dc energie in dorneniul benzii intelzise rr, senricorrtltrrrtolnlui
;i prol.rabilitnlile de capturt i' elct'tronilor $i gohirilol pe ele sint mrrr'1ie clcr
lXrgimea benzii interzise. fn fig;rra 5.28 este rl)prezenliitr"l rleperrderilii, de
orientalea, cristalului a clensit[1ii sarcinilor fixe ;i tir,llc:aitelol clc irrtr:r'fa{il.
Curbele arr fost oblinute prin oxicla,rea unei prol;e rie siliciu in 1'olirriL rle
emisfer:i, fiincl posibili, expunerea in acela;i tinip ri rirrer i-:lliciir,l-i t1e olien-
t5ri cristtl,logra,fice. Densitatea cea mai male dc siilcini fire ;i Cle r.iil;ia,ne
c1e interfag[ s-a oblinut pentru orientarca (111) i:Ll rlensitr,ttr, reil nl:ri ilicir. ."r-:i
oblinut pentm suprafala (100). Depcnctrenla cle tl'ierr'rlllc* ci'iiit:r,1inh ai'atd,
cril, aceste centle sint localizate in regiunea inlerfelei. Lt;r:alizale:r lrl inl,er-
ta!5 estc clem.onstrati qi tlirr experient,e do ti,iere si intlcltd,r't.r1,r'(f ir, unor
stra,te de la suprafala clxidarX plccum gi c1e experiente de foioernisit'. Ase-
rnenea experienle aratri cii, acestc. centre sint loi.aliza,teirLl.r'-iinstra,t dc20i
iingil, intelfa.t:i.

D. Metode de control a rlensitd,lii, sarcinilor fire fi ctr,Ttca,n,elrtr d,e la
i,nterfald,

1. Sarciniie fixe

Densitatea salcinilnr fixe clepincle clc contiiliilc de rl:idare rrale sint

nrer-liul ambiant (urnecl ,qatr uscat) ;i tempclatut'a cle oxida,re pre1.-rtllt si dLl

I lnri i101 i lrit i

t-u
il

!-
.:,1 \

{-(:

c -s0 -5a -10 -20 0 20 /'0 6C 80

i,atitudinea unghiulcrE (grade )

Irig. 5l.a28in, t-erfIa)efdnsiintatfcuancslaiercittl.cliioorlicd'nctalareaintscurlpar!.rlficlscii a c:.ipcautlol.clc
rl'istalint.

162

t9t

'?tscsn uail-rlio ur e?a.tuplxo BDtlI
iaJanp.s0zr0p€r.6s)rn]TTlt€sI€,IJiIaatrfpdaJor.outucDaml l ac€upJaat,asFr+uorsx+raoila.ts"'qorut.rr'ir€13aocu-rrr+E.trarnpccIrrXirrrl0Olrlltds'.+-u'€QrIcoOsa+np*Zol'nJoSclxns'Folu]proy.5r){ot'Ix$lIeuocIzasIvJnnEtzS+eus'olBa5utgetuxi]+oEuI+cIuolsrpITsrr,aau1Jpg1t3spo1p1l1xltx1so1op[
.poun uaFrxo ug u1,iqo os oir?Irruis a?€+Inzatl 'LTllzuc olaciurru ul 'o;reptxo ap

g.rnlu,reclural r?crur ruur elec ru1uod auriiqo os /"0 ts KcrrtT laru €ac t;o,reolll1
oeppaocrl{oc"ruclrrn;"quugoc(pl 1rni u'1r1{ccap
'nlclils rijp d cIIl clil op oqo.tcT n.rluad ?i?'rl oJ€plro
ap arn?Eroclural
loJ+ss a\IJ lollqlr.ts €at'BtISuop
as q 6Z'9 e.rn5r; uI u 0C ue1'egrct:cluc no g1t{lnurui
Epo,r 'plso op Inln?Erls a\IJ Jolrulcr'ils €a+E?rsua([ 'oau
,r:puuq ap Bauntsua+ mp €urrrrJa+ap os
gield
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iado;ardns
g4f+lsuep

Iln alt parametru care determin5, clensitatea de sarcini fixe este t'ata

de rS,cire a piobei de la temperatura de oxidare la temperatura mediului
arnbiant. Cu cit rata de r".iciie este mai mare cU atit Q,7 are o valoare mai
rnicil. Bata de r'6cire rapidS, nu d5, posibilitatea ca sd, aib5, Ioc un proces de
oxid.are semnificativ la- temperaturi joase qi clensitatea de sarcini, fixi,
ri,mine micd,. Densitate micd, de sarcini fixe se poate obline fie prin oxidarea
la temperatrirzi inalt5, (1 200'C) fie prin oxidare la temperaturX joasil (<1000
"C), ins5, ut.lnatd, d.e un tratament termic la o temperaturd, de aproriuiii,tir'
600"C in azat sau algon. Pentm a obline o valoare mici, a lui Q"r, tratrLueit-
tul termic se face intr-un timp relativ scurt (o ori, sau rnai pu!in). Dacii,

tteraatadme esnatrucilnai rfeixleocinttiriiniplesdcerecqitteevaapooria,c1rQe;stecrcer.iqctere. ;Pterrineautnimnapltelu, idec1nestirtaa--

tare termic5,.

2. Capcane cle interfalii,

I,Iicqorarea elensitS,lii capcanelor de interfa![ sc face prin tra,litr,ment
ter.mic fie Ll temperaturi inalle fie la temperaturi joase. nmed.iat ciup.L 9i;
a &\rut ioc procesril de oxitlare se face tratamentrrl Ia ternperatura cle l- 000"C
timp cle o jumd,tate de ord, in atmosfer5, d.e hidrogen sau gaz inert ln aceea,5-i
inciitd, in"care a a:rru.t loc oxidarea. Dup5, tratament se clepune peste oxid
stratul metalic. In cazul tratamentutui Ia ternpera,turi joase, stratul de
oxid se creryte in atmosferd, de vap6ri c1e ap5 sau c1e origen, apoi se depune
peste el aluminiu pur qi se inc5lzeqte struatura ia 350'C timp de o_ jurniltate
^cLe or{, in atmosfert, cle-hidrogen sau alt mediu neoxidant,. Se ind"eliLlterir,zS.'
aluminiu qi se depune electrodul metalic dorit. Erpticalia necesitEtii iiepg.-
nerii aluminiului este umS,toarea. Apa, carc
este prezentl iil toli oxizii,

inclusiv in cei crescrrli in oxigen uscai, reaclioneazi, cu aluminiul metalic
qi forme'azX, hidroxid. de aluminiu qi hidrogen. O parte din hidrogenul rezriliat
poate difuza la interfala Si-SiO2 ;i sX, r'eaclioneze_chimic cu centreie les-
i-oninnsAainlilaecUpveenteruleccatrplcc.ainneiespdreij.isnuuplraafcaelXst,eiinparecesst{r,pfuenl daci eesxteisatSd,ino urmX deve-
serie
tlt re-

zultate erperiu...entale [16]-. f-ntii, s-a obser"vat cX un strat cle nit'rruu cle
siliciu intre metal qi interfala Si-SiO,
blocheazS, migrarea, hidlogenului ;i
llu are loc rnicEorarea densiii,lii capci,nelor de interia!5. in aI d.oilea rincl
s-a gdsit cd, hidrogenul atomic este mai aotiv decit hidrogenui rno-lecular
in rdducerea capcanelor de interfa!5. in aI treilea rind s-a observat cii meta-

lele mai active, ca aluminiu qi magneziu, led.uc considerabil d.ensitatea de

capcarne cle interfat5oin comparalie cu metalele mai pu'gin active cum aI fi

platina ;i asiuturualt.elninainatreirodneietrreaatammeijnlotucllluteirrlnuiic densitatea capcanelol' c1e
Eo este cle 1011cm-:eV-1
interfa!5,
iir cazui clegterii stratulli de SiO, in atmosfer5, de vapori cle ap5, qi 101:cm-2
eY-1 ln cazul cre;terii in atmosfer5, tle oxigen. Duryd,_,tr-a-tamentul telmic,
clensitatea capeanelor de interfalX scade la 1010 cm-zev-l in a'mbele cazuri'
Pentru cele mai multe clispozitirre, o asemelrea densitate rnie5, nu are efecte
asnpraAJpeinrffoudrmalad,n'flie,mlo5r,siuorra-.tdln, pfriginrrma e5t.o3d0asecorenpdruecztianntileci,leinnstirt-aoteastrdrrectcraupS-,

I"{*OoS-" cu semicondrictor de tipp supusS, tratamentului termic la ternperaturi'
joasd,, cu poartfi, din aluminiu. Comparincl aceast'6 curbd, clr cea din figura
,l.Zg *" oiservx, ci tratamentul temic reduce considerabil clensitatea de
capcane de interfa{'ii.

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tzJ {:::;rilrlsd lsriJ ,L; r:,tlllcIrr; Jl, 1:Juriri.].rs : riul;a[tr{ r{,.Io,1 t;a1a ezu,rirl,l" ,,r'r?,,
',:;n iiluo cp o;r+ua, .rouit ur{r,rur{u ,u1 arnir prro Jp In}t.r }s u1 iaCr lrznurrq
lJrrurqroJ?cala a{.so ad ea.rr;.rglul .f

un-isnnlrdinlp.i'ti j'Iint1a1l+n-{B}pr{:lilxrr^lorral'BpsalsB,'rprr.i_rlJ:r;x}droorr.urerrJpa,n{e'rstidaurvrrnz1v,JE,Sa(zu,Era{,qr5i?luoar,lrapo,rsrqtsgJ1i(,iee;dg,rucalt1o]up,rprIe.rloprc{tirB,,ruJo,LriauuJuraprtdillr.ricu{{Jatra3'tIr.Iolu+J".LKlrn{r+.srl
lniraio,lprq alsa asuof l.rnge,radura+ 'nEuJIrpJ{oa?lar?uu.rr3,JEcerc1rdrul,uzeoaprurniuprrlsrllus.rauo+apurJnE€aJn,I,;,(B-c,ai"rrocJrl0iprt{tlrrna+{.rz&cG{rl*-l

e-usa'ncel-^,|pq1u;rsnu1out.T{osrah,dr rd1fn,1eni .Irn.3+yua'.rruour.+ra,i1l.xr}J

5.4. Hiectcle ioniior mobili, nennifo{'inilirlilor laterale 1i capcanelor
ionizate asupra caraetaristicilor structurii l!{}S

in bioxidul t1e siiiciri eristd, in ge rei'a1 ioni do soclirL ,si, rnai pu!,iiti,
tle pot,asin qi hsieclrrloegliealsi ei1azTi-p1l9in].sTb,rraatou_ltdeempoexriatll,iurrtii,t'ritntal it.itrnn:plted.celeor1d5i-0n"nCl
ionii c1e soclirL
secundelor. I-.,a aplicarea unui cimp electric intcns pe-stl'atul de oxit1, de'1i
ionil-o1 r3ste cleslnl de rnicri accltia se tleplaseaz[ u;or chiar ia
mobilitatea camelei. (Cintl sc tplic5, pe_poart:i o iensiune cie 10\r pentru
temperalura
g1'os-itite stratllui tle oxicl cle 1000 -t\ r-aloarea cimpulu: t-iegsLtrelad'5e.'3130162\s'/ocuror)i.'
ioprr nobili (cu sat'cinX pozitivi) tlisilibui!i ini'qrei c:t.in
depiasa slb influen!,a cimpultii electric, cirtry irrter{a1a .si1ic'irr-bioxiti *le
sssiinl*eilvlp,imeecla;riirufcsfaac,ielialcn,alrassfcasuiilriici,l'cciicoliiruniloul-alabludirto-iti.'anxsiiDedeaacsced1cte.e*settpisiispoliililiclac'nniriuuti,zlraivr,caela,siticttiesln'peiducro--yi-iulzteeecitttcli(ipvtpoi.go1.zsI,)ia5l:err!.,pci3-ili3e"eiLL:stiii)aas.nrptee5Iii'"gcaia&ntittioii,ivlcrinXatlpiiloaeIiunrr:pnalr,iinoo,sigoilt:,airblattlie1ltiavcrlllr5iterr,,,

{:iig. 5,1}ii" '- Dtpllsrt'c:L iouiioi luobili itr
irior:idui ilr
elci:tlic : ri -sildicisiutrisl:r,t.brIiirn'lflitrtoirni:tarttcritici:pipu)lui-i
cltrcrt iritrrl tculriiiiri p(r tl{}il1't-it; it lils-
itibuti:i llnalir dr.rpi r',piitrrca utlci lcn-
:;iuui irozitir-c 1tt ltciirti.

i,-- *--

b)

coltri3co ia creqlerea s:i,r'cinii tHcelCninsSisutenrsnit,topnolczot1inteitvaaecmupiunerauptlaoctau'ertii'oi2n0via].t1cieiorsno-tgdlueiuonoeelaoilalitlandocll-ii
stratril c1e orid. a1 siructru'ii platb, spre valori negat_ive, pe cinrl aplicarea
ionl pozitivi, aplicarea unei la tensittrtii
plasi,ea teniiunii de banili, o a
negative pe pr:arti, v& contlnce cleplasare
iXrn;aeui tt'leiinp"qlailntii spre vaLori pozitive. tit-.

.I AR

69t

aru rtsp 'E{elilul €ac op .1i{ry plesqdap also gc r€runft rrtr iglrur} 14 -C ,t?q,ina
-?q'-e./rr-r,olrCcuIJllsooiqq.Jrrcrdo€T{aDur/plilV1asJaurloJfJoaolro1?Suc€sdoe+ar"-IiC?tJrsueoc€,€lrcrnceiltooso.muqrndceucar(r{pgJpntonqplE.rr,ruz"oJrvntylsosruoszrnunsp.ptos?u+oc+rcsorteoseJg(ExJtrao''p.l1Krr,uoniJeoFlnrpruu?na€oq1lliuJfleaerts-dre{JauupaJr.e+r,glllFqu1facrul1crpitiu1.urnouxr1aquorr..ucu.rogpcaorpa"I€gnpig?Iep€ir?tiu.ourilltrnpsfl
.-p--'gl,raoupsgsrrlurrn'ou-gsao+oK.[rroru€ol]rru€*porr+nrcs.olqpJrurlr.dr{r?uJuue€oo,laorJolg'rr]usaou1eJsn€raqoeJoouudlpsoy"nrrceoJl-ro'rrsn'riol.nEErc+lq1r+srrna",srcisu+€nKsnsoJolt?rcup8sl],ro1{Iv4n"'Rr1prA{)J!rc1n-l}a3rC?sJuuGDirr\t-nol?g.c'lrc1|+eir€7sl.sJi6..iErFll1Jrrra(o/ilt?rJ-c,Iaqrc-uo€ooJJctcr€rlrluccrncnlloT+1r]ecrssr1rurl},u.Jinis1dolruia]}r81orlar€mTeJr.zrepr€€aJaJp-,ps1r,aiaouerprld"Jells+unr.rJ"suoeroruSndt]
.-rnos1r.'ofucaI r.nroclrwuzovrqeard{n-,dqru.rr1rlslnipurr,rrnqzlnEDuIa++nIncgirJ rTr '[_?6-g5] riulnrrrrlsow.iol r?ruor
nL-s agrg urp ipciour'.rolruoi n:iarisu
faflu.aB--s:{sdi-rlIou€lJ€spralt'laicpusiunl€crd(loox+ry.efo1usrluoyul'lrorpu1cnq*opJsolnFIn(JnIj,JsanrprlooucdlJ'unpnorooFrruslilllrqasssolluuqs.rouju€-uue1[lnler6occcolca6rcea€-oi1nr].c\rr,oaptelrinJeourJsape"oullrJgu3lelsdarsouaa1r-npruculE1"nrrnI.arooa1idylrpur9,dJJuru.J19lp.o:J€e;IrIp..n-ic34sIru1,1rl)orlgr?auooq.8.r9lrta,sernup,n-ctoulrtcodliupzcKet.ur1outcriu-ri1Iurraa'oJoa*r1rll.uqslclrog1erlr5acr1luuglouotgou':r'tnlnsgtuaprrrrauor.orurca.,dr1nrr"slceouermu,qliouquron5q};ucrrirrro?rnee;rJl,.rpcp.repiu.rc]rolelprrIeoinirurolg.suseTlrri€rtordrr?1eiolrr.naeprury-croz"o.pgJ,s,rr11oBla:1lquipanluaasou|a15ae'rlio.x3.d,oarrraoieuoiups!1pruoJn;1obrltsblpSorru,uli1ennfgcsaonroou1saa+r1
r1cuo€psrol rtotO+ujSJ'-ifIASl rarsruiaoloJ lnFe.rd
Ll=; o=J €.ror,r€q gzLa.lo*arur
plxo rlrll urlrzotf guol 1-( uarirs urp ais
-JOAltr o3ppsInnoJlru.rrLlsnudip-ljriu.otOJicl;S)I-aISoJ+€+{ntspJ
rloclqr

-Jclru TIr-Srpuli[lr1s.lluu-orr!ir(cqUofl)l.tt.u,.,rl;])s1eunnr-3,llrni1i
Ilnrqr,t

'e?t){ilrlor?coio arinlos tl-,rlrr{ 1,uzr.re1od
p'llon.rrl{craslou1uer]pnQu3J,relrlc.{roldourlrontua.srrplnr(oprrXxros
op In+B,r:ls in.rd ;ac1;1 gclnrl as {uo!

1i altri, founir,. Parrta clu'biii fiuale in leginneil, tle tt'rllzitie esi c nai rnicd,
tlccit a curlrei ini!,iale. Ea poate fi cousiclet'tr,ld, c:r, o super'pozitie 'rle calracit[,li
laun eltment
alo irrior elcurerrte rnici. tensiune:l cie barrdi, piati r-ariincl tle

I Oto

El ectroni i T NO*
benda de llivelul energelic pentru

d ucti e electronul pe ionul de

sodiu

si0 2

!I..trcil.t.i.c(i.'r,pii.(-:rn- -tru licprczentarca nitclelol cntt'- ltis. 5.36.-Curba (.',.f(I-t: n-
inainte si dupi tratarlcntul terrnic in
electronii din btrnda de con- prcz(rnli tlnci tcr"rsiuni aplicatc : 0
tkrcIit'a siliciului si pentru clectrouul tlc
pr,: ionul clc sodiu cliir oxiel. ilustrarea ndcrrlornrimfoirrnrriiitirc!iulolrblcailel(ailc-. -I'
datoral{

la ultul. in nriisuleitorilo de fotoemisie cu spot mobil, hrmina t1e la o iilrrsi,.
corrrelrtionalii sau de la un lasel lfe-Ne estc focalizat'ii, intr-un sporl rnic
;i st, loloserste penl,ru excitarea, fobnernisiei intorne a electronilor din siliciu

irr SiOr. I)eplasirrd spotul pe probi s-a gfsit ci, fotoculentul {lste funclie
rle pozit,ie.
llioxidui dc siliciLr contire, (lc ase,menea, capcane atib pcntt'u clec-
tloiLi cib si pcntru goluli .'] cii,r'ol efecte se s[praprn peste efoct;eie da1 e de

jorrii rnobili ;i sfd,r'ile (capcanele) dc sulrrafalX,.

tsfectele cimpului clect,ric intlnse tlo deplasat'cir, ionilor mobili pot fi
iui(r..trlrrl rr 1)o lilai rnult,c c5,i, pe cil,l's lo vom eKpltllc itr cele cc t1r'rnear:ii.

Lrrfii. irebuie luabe toate rnd,sulile de culii,lenic peul"t'u tiirnina,t'ea conta-

rnin&rii cu ioni de soclin in timpul plocesuhii di prcirzu'ate a, strnc[urii.
'1'rillul rlc cualt in care se faco oxidrlrea t,rebuie ouri,lrit in prcalaltil {olosintl

l:Lrrrsi e&ll]rc{rre]esateccLdseeomxiicgEa0rireilfstzcda!coqDi cho}n'rtlrrao.gtierlntlceiriiooiliiirleclc[9s,oi]t.liiSr -tnlaocfbslLclvi irmt,pudtcr

proci;sului do oxidilre se jrrtroduce in atn:rosfet'a de oxigelr uscat' o cilitt'ita,te
mica ,le }rych'ogen chlo:'jcle. in pius, acest 1ri'oces condrice la pasivareir sf-,ra-
tulur' de oxirl fa-!d, cle inst abilital,ea innilor', oalro aL pnl,ea f i tleie rrnirrabi, de
rlepulorea ulterioarii a rnetalelor pe]rtru poart5, qi contacte ohnrice. Du-rd,

{:reitt"rr'(}zr, stlalului rle oxid ac{)sla lloars ti eontaminat cu ioni tle sodiu irr

t impul depunerii sl,r'al,ulni de fotorezist care contine ln mod uzual ioni tlc sodiu.
l)e aceea,, dup5, ce are los opem,tia, de fotolitografie qi se indepS,rter.zil sfratul
rle fulorezist oxiclul trebnis our5,liit chirnic qi sd, se indepi,rl,rrze din el
un sLi'r.l,i,tle 50+1504 d.in porbiunei, care a ye:rit in conbacl. cu fotot'ezisbul
al fi conl,arninat'X cn sodiu. Acest proced.eu este ileces&r in cazll cind
;i car:e c1e poartii, vine in contacb cu fohorezistul in timpul plocesuhri cle

rrrid.ul

lllbricare a stnicturii, rleoarece sint cazuri cind se foloselte drept rnascir,

rneialul c1e poartd, (de exernplu, molibdennl). O altd, cale de a micqol'rr, efee-

170

LTL'TL

ea.ralSa.rc li 'ilZl tiiE+:aeclec € artso1p\rrtndsaroa
yiir:Ju.rdrs aD ritlnlur,ialoll ql;;u;ro,iorur,e1 e1"red flIE op or{;el
+tsJls ul I"r'eliri-)t.i{,1r ,{oi{.ro}'f ;rncl rr,r'graua8 r: d,*i1 ap la+ur}srro.t ,u'.r,iu,roi.Jr{rr,EI
o].tecl o op otl orilpuo, aJ s?oD orsJa.\rlr ci' Inl€Jls ui Xlrra,tus op .ro1r,ro1p1.riir{
;atie,rllracrio;i ua.rc]ia.ra g.tt,r".a1"i, n a,r'uor.,r*11 'rrrrro.*1 e1e riplrsrielur os,raaxp

itrlu;rd g1ear1d,u uarnrsual ap cliairn; ril zIlilggI 13[ ?a]su.Lrnlrsnerruei'Eu]u.crnsJeoolfr r]o'tre]
-icedec pltLrzo.rtla.r as ilptr& igg'r; t:rnFl; a1uo.:.
Lrlptrasqo

-Ja.iJ r.rl cs {;Jl?oIE-r. oir atdi-r.rrl'u os tJrrIJ.Jlnt{ ers,rearr{ op tJunr5a,i u1 tfuu;
-iaudu; (,uralsaau IIiF yrrro |Lrr uJ,r.) i'{,-} r.r rIJ 'rr{rrrutil u}uazortl uI 'II'n]o} riilul
--liJilluut;lpriplrrr0o)r[iq)urrlsla),)uJnrUuiqrcorJrr?ossrrrFr1rruF^Bri.ldl,l;irid:f sJls,rB).rtJr1it1lrt,rr),iJ'i.'.)iIiiu'f.o\,l)]qotlat[Jg,.r)ptpaparzsJirul;urrp.,\rIdaipJgliual,lra)rnlr)uoDr,rorrsa.rqcla.Il,l,:1u:oi(rcrtr)ruro:ttzpi,tr
opr.rn-clsa.roa 'rnlrur.eiart{uo'Jp.g1?saIJl"llsuaJ t'l!liJoJr-lti+li,rBrqJuruo{raJau,irtlloapOo.lc0sfTilJoq.rrpl n,prrrrlru,{raogpg?(oJIpccp

',t'tf il;.9,;
rao.r,.';r1S.'ls'?c'i^rrl,rr+qerjcieg1ru'o'tl.pjgraeuay,rrnl8nrl5(oluruyofargsu.r'trgip'oa.Arg'.on3lur1lrJe]o)pdp(3"|o.eIrnaf:zluatJ)n1r-rct5ru-ll(irzll"rtss'Urcupl r/tfatr)tlan+l''iqu(uttefA1lKJ/gfun)'gol)puBroo,?iD,n)rti5isi'zort{;c€.er:rrrltnrlolgru.1r.u,ur'F,a1r?pucatrllnu^zJorroo,(rosci^r{.Xotr11,oJr.
i1a-l'IreJp,r8nJaooJrl;liae)lsrrrr.ua.arnc(lsfoli,o,q,rrrrd3rioegg1l ,uie]'rrrr,3iiu)oiouap]prallucrprrllpuupcrrc?rploiludJ',or€rc'tirrntr:-{aL,trtZroLl.l\glt{'fgli'tpJ-i*ep)lud),,txBrlrxaJlniarns-r-5oiJ,pu.tr1ts-{pr-llJ1Titoiz's*t6s1uiyrlc,)ulI1lgoltr,s'i;arst.1nr€o.lrtrorsr.rrrq{oSsrcuuOrra:.,rI4IJt]
,uplr.erI urp ira,rl a,rr:c rrrroJlcalarsgiLtaiu-! op,l3put:rl ulp co.rl o,rr:c olrJrlorT na

gTr-i.JlI€)EIn)pL.trJ€tr?)Outo'Srg(cttisrnrr;ruo'unca.iours,rarlenlsnisercz;oauK,..{riu+qlT?-rrtrcsot"u-ogsn,trlolea1a,otiitrouxolsariprrlzalaaKl{p.zaTteps-aposuIupil"ldlE'8Bap.a(ri1rlosnrtsr,5rtootarl.,erru1.rauoorzrl,r,lrr,d'rnuo;?u.lrK,r,to]nlcll,nluuodrlrrrrroru,aJrro.r11,lulrrzr,,rrumoao1u{zqnon1..r3,frir}lrip1til
"toa3J1B'cB1;?ir'-tr?r,,Jrc,€Lril.SltrtJaCoiJ--r{rliI{diJJnp}ocl1(rr},.ur{o11l}ngS.}:.otlru?1ldu]u1qJo?[z'llrt3rtu'lolalsIC;ruBa1erI;in,ue:]od,I'nB1a,J<.rl{zo)l,]r"g.-aJt?u?;,'d;ia-a'lclptrtrlx-rainllust.r9lli))gr!'oci.ll)ltznU,rr.lrInrFiiEry.i}iisn

1.1"t,plt,'t,Lultlt't,i rr.tnyntorlway a1a4ca{57' y*

rnplIB{IBa r:luulanplio3 "Junrs.rci.rrr op rnpr}u,{}s
u;tlnsu n{tr{urnl 1S Jr.rnlr:,lcili{ra} a{o}aJJE 'JInrrs.raru[ ?p [nlB"r]S 'f:"1'

o'Vp0t1Un.rr.r1.;)ri)uti[e'ltS'J.eIUp']rIli.J)crtr.{rlt:ti: y00q,if},)lj,) 6{}lS -lll tIint(1til:tLt:lso.t,-relsil,.tit,Li,Srir{:iil SOii

Ji) Illlll.lo i.)3.1 u'] {J lsa.r'r iJ,lJa}
Xrt'pigsur..Ynrnni{slsl--iatlli,Op)ul,'IuraS1.arsi,'tli'imianqsan:sSneptIagEars,IrrIiiug: -Jsz?cuO,tIa.]ulslSranlloonoip)Sll'rut+-,lrclccqaT{rJ,l{calj)rl.).nIlnnir1rWr[.ilrf].an,rr.IiLiSot'p]uf]i.c}Jrrzllfniozauli?ll,i{ot:'}}rrJrl.u1.rldrvraio1r-dllquiuuIpiaIrapuJJJr'i.Dl''{ilrllaolpciJli;.rlrr^.i{tr\tii"tqr5i.l}rlns?r.lrrr?rsa{ii;iao)stpp-i
r-ntolntplt\x.on{qts{.]t.}glt€aipga.al.pRLouloisl'rijirir;tsrcgr,arieDoallaiirp1Tul.rriBi3,'}er1iralt.lrJJ:'r;1rlr.I8la,ro:i[ui;.rnlniirlnprs{}us.rlrJa1reIs'}nLr1acnl1u1nui
qns .ro[ ua,r'us'u1dap or-nprircrpaidru5 g1;r1s op In]'s.r']ir aJ]fJ op ,,rjt1r{ec" lurs
i"-*cpaplairiuruFooola'ir!pEr.{Irnr:|uSrltrotl,prIl,s'iB?3uJ.roiis}3uolcllooa1zpi,u.Brroa.ulsIeoigtr€znslFu(-J-grtOtlut,rIiSlto;.1pI!':t]ltrI1,DftssIJilss.r;-lz{1'grIrtiJg.rIJoqltnlnc{Ioelist {'JirI ii{{is tirpos
eoiitssaEral i).lVoy-srro1g,:noadglnlu.lcoiolLplloEzl1cllrilslrIe(rpr.s+:r'B;)PJlsT{riill*r)ti}I'Iutolg.rliaI'uiltlr.rl;Ti'al:p.rguict,irtdtt cll oi(lr1p o,li;-
prxo ;lp Il1J.'.13J'15

uzri'ua.r e1'uocI ar
OlSi ,lo{I1ioi a{a}

q; atLii fot'init. Panta culbci filalc in:'egiunea de tril,llzilie os'Le rnai rnicd,
decit a cqrl:ei iniliale. Ea pozrte f i consirlelat'X, r1e capacitX{'i
ale turor elemerrte rnici, tensiunea cic i:attcl5, c-a o supelpo_zi1-ie la un etrement

platil variitcl cle

I 040

T NO* ; / t't aintc

Etetronii ?n Nivetul energetic Pentru -e u4
banda de con- electronul pe ionul de a)
sodiu
ducti e
v-v
oo

si0 2

gTeritgic. e5.pllitr:.n-lru Iicclpercctlzoenltiiardeian nit'eleior otltr- piIn:r'acigzin.etne5{.a-3s6iu.cn-lucpiCitielt'rnbasatiartmr(llic.na-ptulfi(clIat-tt)cn:n: icQit -in
banda de con- -
rlur:tic it siliciuiui si pentrtt clectronrtl dc
pc ionnl ch sodiu diu oxicl. ilrrsLraren dolormlrii curbei C- trr
r't! ilor le ir'
dnlora t i ttttt nif rrtrti I r'alc.

clgiaroii snuSerliteOfuorlrfl.ot.isoiDnen$eatmpel5lidrp,ssseianrniluddtr,drtsolepreiollexatcudiulteanprfeeolaatposrfeeoomrtb,oilisf,eeies-nN-iagseiuegdie*s,sispnticottetfcrmoXncoefaoblaitilzo,eacllttent[cmleibninrnottranu-irlldolneresstltlaepinoo{rusl.sni-ltmitccxlsiiiucei,"
de -poIzliio1,xiei.tlui t1e siliciu conlinc, de ascmenea, capcalle atib pe-nLru ele-tr-
rinlirpon,liointcuiriiirfLi.ui lrcIr.inilnirifbeoetccbcEtgrtiiJileipftiecoleqenunilu.citstaaribdmuitdeei,pgrr'usuioll,eolollufuda(eiiclt'iueeaczipel5im,ncc,ciaSb,5tnr,p,iriiemcoenlrcliiicnir)eeaudfteln'lideccspte,1eersoocrrSdcnvpeeelor5assm,ftlu[alepe!lnu5pera,ilier.appts-1pualclernlelDpcaprt.lcieLupjsloatnecercialleiolrmeferciccnmaleaeorlseebuta1ridlu'inaouprotetcounatrtzdaitiiel.-i'
'iiIltsune6r&glerirnrdeees&ticeccuXadrse!eitnlmsciigiaqel'oenresueaszclaaiic1e,co$onixcihce]i'nacrtlr6raoa!g,iettrlnebt1cLeirriielooucli.diLedyei,[l2isb5olld]l'ipnSre-daaalcoaibb, siilcrtrfovtalior'nts,pindutell
prooo.sului clc oxititure se inti'od"uce in airnosfera de oxigen-uscat, o oantitate
chlolide. in plus, acest proces condtlce la pasivare*.*1?-
inlca,le hyd,i:ogen cle insr,abilitarea iotilor, care.ar.pulea
fi clei;ermiriatf,' de
tului deoiia tilX ppoeanrtorutipcooanrtta[,rngiincaobntcauctoioolihnt1ieces.rlcDliuilpSin'
otuiiir"ot"a ulteiioarii, tL metalelor
crdrst,el'oa str,atului cie oxirl acesta
timpul depunerii stratului cle fotoreiist car-e conlile 11 mod uzual ioni d.c sc,diu.
ilceeaidupi, ce are loc opela,lia, d.e fotolitografie qi se incl,ePd,rteazd, sttatul
,ne t,,iorezisf, oxiiiLr.l lrebriie curd,lit chirnic qi s5,
sfrai tle 50+150-4. din porliunea oa:e & veeit se inrlepd,rtezc tlin ol
rte. in
contaci, cu fotorc:zisbul
un este neecsar in cazrlt cincl
ar fi cou"1,arninat5, cri. soiliu. Acest proced.eu
ryi car:e c1e poart5, vine in contact cu folorezistul in timpul procesuiui de

oxidul
fzlbrjCare a stlrcturii, deoarece sint caz,uri cintl so folose';te drept mascir,
rneialnl cle poartd, (de exernplu, molihd.enul). O alt5, calo tle a mirlloffl, efee-

1-74

'rrT

'Ifa] tiig+t,leclsa ? ar€o]E?undsa,roc
ea.ialSo.rc r-i,pi'c5u.rih:l ap rillnl,Br,'1a1od ca.iu.roiariu 11 al.rerl f iI€ ap er{ Jqll
ul p;.rud rr,r'g,raua8 'u '.[iui1 op ra.]ire?srro.r ,ea.iu,ro*or{il ,r?[
+'uJls o r"rls ll.toi.rriu ,{{}irJo- ln:Ie,r,ls rii eilrD.tuu ep.rolr,roryl.liir{
oil crtrprroJ aJ caal oisJOrlrlr oi)
olred op

ratlerlrtaauou ua,reliarc Krrr{r-{,ra+'a'p u}.il3rril[r1l{ 'rrLrrr.{rL}[ oI'? ]iK ]rsrio]rrr l.ls,ra.r.xp
ll.t1u;ld plqarld'e uJullrsrrrl ai) criJ,lnJ rrl zl[i100t EI r? ill,niseur KJurilro'u uoiel
-tceilea pliLrza.rclo,r as [)r{i1 'gg'g r.rndl; uj fr,rasqo as ur.nc u*u'ostol i)]rror\
-ra,u ril rs,LrJ,r"olt]-r ap aldo.rtlu ils fJIrIJaprcl ats.ra.tui ep tlut-trFa,i u1 T:{uei
-rcr;cl,u,t ''urolsacu lliFpsrralrrr uJ.rdps.rlo LtJ'nurrunl eiutzo;it1 uI 'Itr'u1ol uiu,u1
n--Jdrunr3*pirxpr{oou)prup}islo)arnrc,{1uurr1cuo,JruaTss |rgL{.lrrulKuaiLtiulLJfl.8.J]srJs;rJjTaJJyrdlt'.,')rtyt':lrot\*; tl=llTJJtgJI'p.dEttpazsicrulItttps.ttdIa}p'cpu1aelalmrspucra.roii;8}.l,.r}rloaptutot(iu0iar)olt{?pi1t
oprlnclraloJ 'rnlnureoru{ro'Jp.0ils?dIJtai lsiJa{rT{ Jia,'rtlt}?.'PiI.ritrsltu?tt,}JtairaJlpilJ.lgJi?J,I)ol:.1rc[gigtirrritui1roapggftJg]polpr

'uulf it; p
o.rt3,,!-r}te ail 'urff.tcna no gluecl o : aloul+sip altrBC gnop X 1iti,-ra.rd t 'FJ !^Josqo
p,clgru'(.trceyrnuc5lro; rrsrrrpa.irrorrlor}rtttr+l Ienaziu).nI'rl3Fza?rcrl.rrtrlrol'irr2tc1lJgll'pgrllo:,Din5ttr rtg gl'tllnazo,rdo,t
o"llSsa',
trnlu,roduroi r1J
,orlo-e:r€pr,ppri8cnl.rirrf.iso;)r.r(lrrlonlaer.suul{ulaaNt'nlpucgslro,foisualraudu.a,iarggll{luo'Eoe,,rrrr1,u,u:rlg)oircuoa'gqru+piatlru'cr.opr3rutJp1.uplr}co)cllarrll(onlia"u(dJ.,oTire;'i.(tln/t.In,tsp[()a,,intluIL(Jqoo6"rlgi'lI'ouUurtI:',rptl!atfi--ou)p)-pycFu')iBuxd.(t,pac'xrUurlanru-t/srrt-Fl)o2;pi,ult'Iruu"p-t'oIIL-I;c€(ITt,Io.tiuzrs'luU'€iE1fiooiJtfl,t.r)TT'rct-n.gililx'ltiuar'itasl:d1u.1lti),r,ptrmrlroutrscu1trlooqsSi"ntir3}OuT\I.oonrIl.Ju.pnar.
g'"€.o-li!loJorJ')ilt)tltitpr,,iFur;{r'u)}.)i''ilIrorrl3Druo'sJg.r'crBrE(eintlcdur.r.a;ruet.uolrDaioo?u,srroal-li[nrnluo[nsii-{t(rio;z,?e,moatoor,.]c(r[{c'W]riiltR-Jiqt,io{csn:}loi"u.fss1o.gnrt..lo]lrllnoilie'T'adEaiJ;nriulx.oautJo:oz+][lrlsplEl3rJtorrrzoil?i]lraoiJrlazi.stoItl'?stBEpi-aapl'tsrtoiIru"un{prlt;let:d:Ii]1lcloI]?asllplu.crrir1mz;.}onoisalis,St,rrluooasy1J-.alrreu-t,1uIcr3oroi,'r2;irzri.;;,a,rt-trrncoln'lt:op}t1crrtrtrr+l,rrrr+na.onoic1n[ll'rsu0ld'lc9u]..'rr1ulr).9,raor-,'0.r.rglroili1r'u1l)rTei,r,iLrzlir.}aorIt({xttur1ll'itoJ{apF,1zt15?1tn,l..i1nrlr}[rdii-li,i!tr]
3l.tpLttLu)?lt t,{ rt.tnynta r[wa1 ap4da[51 ' y-

rnprlB{rBJ e!.ue;enpiro:}'Jtrlt{s.rorut op rnllrls,I}s

e.rr{lrsu rTrlrmnl 13 lt.rnleroilisa] o{a}ailIg 'Jlltlts.i3rur al} inlB-I}S '!'i

OKrt''pbiglSfriDt-r-Jn\i{liiIrsolr'nu-su,.a-r'oOl.'p'irlI+lJp.IalSJ,uuns;3^tiTlni,{qnl.e"n'tsle1lo..:ri.ne.t'-rlJa5l€a,1orI{u.{leIp-n,rr]1rt:J.sI;1-'rtt)zl"hr1.rOJ}:t.lLilIs.Slrlitil;rtl:rl?orn:elJ1p)S1lr1)uu$+cl,T{{ar?.}rlaLt9rl]Jn,l)rcal.}i)1plpa{nlrrTrl'j}iIa.'}u})[Bini}olu.,,i,lrr)-tioar\lrL]ptiiI{r!liti1lile,|zt)1.{fiIz5iidtaali,pltai,ai}tui"1'J{rlul.t]irtrr"irrain-illc-.i(dqtlil'r;uurltlJ:t;iiat>tIitlo,o]-urca.trirDi-Bt.i1tIuraaslIJr1,).,.t;t)ul,)iiIt'l-l:rn\titi"{lli;5l}illi;tstlall..Etrsrsoraa{oJiJaosSitipnp-\
:t1*:6l[ntti,tirxiro,rI:qi rrBg]]tttagp,aap.i'oiu1Lou:iI,?r,r,ritisItl"JgIa,Ir+:oJtaij1SiItl"lTr ]rIliu'ul.1{loitu)Jyl'rJ-ir-.}u't;rliauf.aIn;riuIplraidl.irJrJrll;ltstn'iuicolutinliti-:
r?r-iitptoipslai,xirrruolijol ofcelpaB'rrr.rXu1rls,inrrr'u.lrorrlcJII)lllasEEp3lrorc.ri{slsur-Olnl{c[opoiiJtlzrir.lur?'ourr,lpUtsoo[€rTigltUlzunS1i'l;1rr;rggt-1tttlg;utlc1l,Sislto]1c}pipJIrBll5.rtlIS+etr"alilsls.,lI-Jl3-tci'gtltorij.g1JtO:liq11tnI,nlldIoot1ssp1,J:,o-li.,irplIiXerollati{ii]t{tplllalllslI(ltd'l{]l)'1,Jll{]ttp,rr.or'{lsstr

aisacl .loysclnapludop T[ci1,s 6O +'€J]s rilun ta,rairnt{op ut,rd tzti'u:t.t c1'tlocI at
ri isEacy'rr:i,rodln,iotulozr iri ir{(}rq-r;rp irigiilrtlorrltlo,i'i:.roieittt olsn,ro{t"froi a{aJ

---a ci lD "
jrt
'rt lllrl1'9n,io.o

ol

a)

1A "

a r.O- rJ -r \.
- 10-A'
lc \Il't

\

1A /

2,!" 2,8 3,2

V,V I 000/ 7

b) c)

Itig-. [5u.3n7c.lie- Circuitul cchivalent al strrrctulii IIOS la inversie pnlcuricii (a). contluctanla
dc tensiuire la diverse tcrnpctatttri (l), cor-rductanla in funcfii: dc 1 O00lf(c).
ir-r

B. Concluctanla cu'ttalului

Stratul de invelsie consbituie u,n canal la suprafafa semicoilduotoru-
lui care vine in contact cu poarta. Prin efect canal ale loc procesul de con-
duclie in tranzistorul cu. efect tle clmp c1e silprafald,, :I!a cum l"om vede&
in parzr,graful care ulmeaz5,. Trauzistorul cu efeci, de cimp de snprafalH,

cn canal de tip r (fig. 5.39) este alcd,tuit
dintr-un sutrstrat de siliciu de tip p
'^--- -''
t.l:----- in care s-au rea,Xizat prin clifuzie sau

| '"' ''"'"!.:"a-i '"'*'*'* *r
--.'. "" .-' .,, ..". irnplantare de ioni, doui regiuni nf

-;*:'"

l;-- F,' ...-r'o:' i numite sursX, Si dreni. Pentrn o anu-

l:- ''' ,-.: j mit5, valoare ir, tensiunii pozitive apli-
i cat;r pe poart,i,, in semiconductorul de
:.- 1,,

tt,7 ts"-i \*-*"-.'i--'9l;'.*^*'-* tip p apare un stra,t de inve.lsiune in-bre

,t-I , . , , , , I cerle doud, regiuni n-F, nurnif Zcaln5a,rlg.im1{eoa-
Di ou
4"5i tintl cu -t hrngimea
-2A -10 0 t0 20
vtY canalului, cond.uctanfa acestuia $e scrie

F-ig. 5.:lfi. c-arliafcctcetruisl tiilcuiimCin-Viii.i asiL- s Z f"t o(,r)rlrr (5.1?)

pra 7 )o

&nde trd este adincirnsa canalului, adicf,, Erosiinea tsretrcaetluelauiiledelainvceornsdiuunceliaI

la r: r, ssmiconductorul este iqfuinsec (a,re los
rle tip n la eonduclia cle tip p). In canalul de iip fl, soncentra{,ia electro-

172

ttI

op €oJopgc o+so 0/ aF,rin r+ * or{ : 04 g1:uod op €ounrsuog, 'gcru.ralnd
e€Brosf+"lrtese,+rpmruunn11e'-nc7l(6)gr*ps'1o0ol€1o-l*o€e$auoricure€:os.iuaorsrlssooallFe"SorndI;t*peoS'.€/''&Joorx+:oclJn"epgpuo'oTop{r€Irn}uu+o"€rsJd+nqss wp €urcJ€s a?sa
rsoJ{€uooltns^gu€i1*rei.olecletoelclseKd}IJ.roe+r Btoprcg/-i1&;rnegofd op rrunr$uoq ?snpfi orJ€ op
arleunxo;rde od 11.ror1*grt{u4
'tla;o1*elc nc,Fptscs'rgs ar{aaup

ap dulc un el gulcT p'1rnnd od

Ilunrsuo+ u erier.re,,l ap plJa?m gu1ntsrnts;1eu{ueodr.?ro+du€xglsir'of6c61gzer;ero.r1qnsger{lite'tst luoJtss
oB Jolrro?9,1;rncl "ealelrlIqou gc
l* ISA]
ra;lor.rqcs ap p1rrpn?s lso5 € rurrll mp ts+suocy 'e{eyu.rdns od ozngip n,rarl
- -€-$op+"tr+drr1ui;qoKr+uEro+rtrpl (€roe+{qe3+rrFoqdomrr.rarlS"^grr.l.crhtlulr{gp1ler..rron1dtusprr€aod+trsu+aryiqlipou.rirlou}rstop,r1r,ir:,aiop1,nupn

!ar1

(ra's)

ri; urnloa u; c.rrourp.r,oip+1rr;nrnlnd+uuxoutrr{tse1r€?Ju+ac€uooJc€rorrr,lrunrBpcroK{lune.r;rpad;rrp'griiulpe{,erd;enrsdngsFr4e1tr

.rolr.roq.K?Jnrl rr;rar1Ap.rdu4 K+r"ro+oep 'rnn1o,r mp q?o+ts+qrqoru ap ?1'l.ro$p a1.<3 /'ri

(oa's) l"0l :.1'Tl
rp 1r1n1rya ,u\b

- J??i Jul dar,rt; op €o?u+r{rrl ed rounrsloaut K^ilcaJo'uo1€+IIIq0ul

op In+EJl,s uip t3urcJ€s alse "fi apun.

'u dtl
cp ieuua nr pjesulrlns cp durgr ap IraJc n3 InJolslzue.iJ - '6['g '8ljl

9iJ'Dod

(e lc) 'iub""':L:n

al,Ics as rnlnluutsc elu,elcnpuoC 'JolrrroJlcala Galu+{rqour a+sa (rr)eri apun

(src) '{r)"1 (a)uli = (r)o

IJJ?s,t? '{c)ef (;roir.rnlo$ eriu.rlrrar[oc Jrcop a.rerrr rlrjr.u i]Iliur clsa r(r)tc {.ro1!ru

tetrsiune pe stratutr de oxicl. Se rnai poate sclie V-o : * Q"IC, qi prin

ulnrare t30]

,,i;.22)

\raloarea i.ensiunii de poar'l i, i:1, cr],r'e a,pa]'e hn'ersia, priternicir -ie nu-
rre;te tensinne cle pra,g sat Ge clcschidere ;i se noteaz5, cu l,-.,.. Ea ar,e valoa-

roa,

r|,l: - -Q-(_:o l, i.rlJ",;.r, i5.23)

" (t

(Se inlelege c5' pin5, ia aparitia stratului de invelsie sa.*cina intlusf irL senri-
conrluetor de ci,l,re tensiunea tle poart6 esbe cea clin stratul de cloflerie care
are valoarea marinrii Qr,). Prin il]'rl&r'c: ecualia (5.1 9) se poate si:L"ie

g: Z -r"r0o1I'"1- l.-n 1. { 5.24l

Ir

l)in md,surarea conducl,antei, a capacitXlii qi a teusiunilol aplicate pe poilrt:i
se determinS, mobilitatea efectivS, a purti,torilor cle sarcini,. Esplesia (5.24)
este valabilf atunci cinrl cSderea, de tensiune intre eele e1ou5, regiuni n+

este misi in comparalie cu lr6-Ilp.

5.6. Efeetele radialiilor

In structura 1!IIS irarliatS, cu electron i ; raze X san raze ^i s-a obsei'vat
forrnarea in stratul bioxicl de siliciu a unei sarcini spa';iale pozitivc
Radialia c1e izola,t,or perechi clectlon-gol [31]"
genereazH, Il abscnla unti aimp
in
qiriagtolileulriiil.eDreacco[rnsebianpi,licryiri ,nou se oblile in
electric electronii nici o sarcini, net5, in
oxid ca urnrale a terrsiune pozitivS, pe poartX

timpul iradierii, electronii pi golut'ile se sepa,l5. Electronii se deplascazi spre
elcctlodul porlii iar golurile se deplaseazd, spre interfala siliciu-bioxid de
siiiciu. Datolit5, barierei de polen-tial elcct,ronii elin siliciu nu pot trece in

SiO, pentru a cornpensa sarcina golurilor sosite ia interfa!,i, astfel cir, acestea
clin urmf;, sint captale pe capca,ne la interfald, gi rezult'i, o s:r,lcinX pozitivX,
care crepte (fig. 5.a0) pin5cind tensiunea totai5, aplicatS, cacle pc aceastS,

regiune de sarcinil spa!,iali, in restul stratului de oxitl cimpul electric dsve-
nind egal clr zero. Aceasta este situn!,ia finai5, rlc slare st,a-t'iepr"5 132]. S-a
a,rftat cd, sarcina acurnulatS, tlepincle <]a tloza A dc ltldia{ie dupf,, o relalie
de forma l-erp(const. A). S-a ariitat, de a,senrenea, cii, sarcina acumulatS,
creqte liniar cu tensiunea tr,plicat:i ;i clepincle de doza to1.a15, absorbiti, qi nu
rle rata ctl c&re este adrninjstratS, aceast[ dozS,. fracliorea aie ca efect depla-
sar;ea cara,ctelisticilor C-I- pe ara 1't'nsiunilor (fig. 5.41).

5.7. Caraeteristieile eilrent-tensiune ale tranzistorului IWOS

:Y In figura 5.42 sc ara,Lir, polai:izarea t,ranzistorului l{OS cu canal do
rS tip rr. in conclilii normale de lusru. tr'l' qi I/a sint tensiunile aplicate la elec-
trozii dren'X ryi, respectiv, poart6. Diferenla cle potenlial dintre electrodul
ti

l1i

frl
gt1
t74
!'

rn

9LT

-+uo.rnc otrrcr+suo+c€J€3 soltpop urol! 'Io|Io.rp uo,rordoJdu u1 13oap o,r'B{r{ rElrr
olso rosJns ea.rardo;ide ur d(guo.rii)7
rnlril€ritso u{unllcnpuoo "iur u1 (gs.rns){t eI ep
rla rn1
eric,a;rp uI crJ:}cala rnlnd
-urlo g+.ruotl lrrpo.i?colo o.r+u1p
ea.re1*oJc nc elio.rosop err ri{.rod 1t}Joltlofi u1
€o+€+lsuotrur roJ€ru,ln €C 'ESJrls InpoJ?cols rA
iiye1{.ue1od ep e{uo;ioyrp +Ioop E?rtu r€ul €^ac o}sa gg'eod {npo.r}calo puolp

''jilE.r

-rl]Bs Jp u-uiiar u1 Fuo:lsrzuEJl- r : raliE,r
-:ln?1lrcJsJ[t)rrJjrp.rrrdrurtu--suqJl'Fu.rrEJl.ur]J(I,.uua) urn:1)6orn.rln-lurar
-uJ .rol!nnisuJrurlr nrlEr.lu.\ '!1.'t 'S!Jl

'lrJirrplrJl elrurI

uI 11-l ilJllsT.ral)8rBr
eereseldcq -'ii,'g'SI"rt

toA * A,A

(q YE

| | ,uA

'"(')IS-ls

riE.l.Irlu! c[ 1!.IJrpuJI Ll
c.mruJn uJ arrllzod 1tII1c
-.ir:s uc.rc1*ar3 -'1y6'c '5tu

tensiune ale trari;listoruluiltOS in nrrniloalclo al|t'o-\ilititlrii : iar s.1'nctrllr'a,
l[OS este ccnsiclei'atX, idealii : (Lt) cir:rpul ioirgituCita] E, este rnnli rnai n:ic
ilecii cimpul lransr.cr'-q:i1 E. (aplorimafia caualului gratiat); (c) stt negli-
jeazii, culeirtul i;ivels; (d) se considerii consiitntl"r nrobilitzrteir, purti,iolilor

c1e salcin:-r; {e) se neglijeaz[, crllentul tio difuzie ,si se ccnsitlel'L ci' csiL' res-

Lt'rleecrtn&etinl,.icaorir,iclai!iac,ad,enanherulutii'ac-lqi1taetetiaetleXc,trt..'liecii,. Cilllelea tletensirine Fe .) scci i11lle

il [" -- llcljl. {,.:i )

.,rrrde -I, este curelr',l:l care cut'ge prirt c:ual inlre sitl'sit, si thcril-, lirii;rit
curetrt c1t. c]-r'en[,, iar rezisterrla diferenl,iall a elenielttului t1.ry consitl,:r'rtt
este clatil t1e expresia

iln: - --3--. (i.lii

Q *(y)pol'

Sul;stiruirid l'elalia (5.26) iu (5.25) t-illoate:l curentului tle tli'ertir se
obline irrtegrincl aceasti expresie le ltingimea cattalnhii cle la
(ntrcle tr': 0) la y: -t(ulcle tr': Yr,'). y == {r

pl' : l'p
\T- -
)v:o 0,,(.,1)rt,zdV (5.ii )

^9: L
\Jy:o 'iv

Dupir, curn s-a obselvat, in par':r,graful auteliot, sir,Lcittr't clirr str':-ltril

t1o ir,r.et'siune. Q,QJ\:Q,0) - Qr(ll) unrle

0,(y): l*1,r" - ,i,,(y)l Cn l''.hl

este sarcina totali indusri in semiconchrctot. Sarcina Qo din s1,rtt,1ul de defle-
rie, ear:'e a :r,tins lil,r'girnea maxim[ Il-,,, , este tlatfi c1e erpre.sia

{}u{1il- - qN,1Y,o: - l/2q,4m. (5.:9}

Potenqialul tle supr':lftllri {r.(y) :2*s '- I;(Y}, uude l'(ry) es{e telsi-
1i plrnctril y. Ca a,ta'rc
unea dintle eleclr'orlul suisii (legat 1ll rrra.sri')

Q,(yt: - []'" - -1-(y) 2*olCo - li2q-qrl'Jnrll + z'Ul. (5.:i0)

'lretruie observat, c[ dacir existir o teirslu:re tie J:a,rLdi' plrr'til, I/ur,, aturlci
Snl-rstituintl relalia
in explesirle c1e rnai slrs }-c se inlocnic;Le cu l;*- l'-,,".
{5.30) \n (.1.27} qi efectuinrl inteslrr}a se oirlinc rolatia cut'ernt-te.rn*qiune de
dreriX.
7 -tl:.ri:
T- -- |:,,Q0 tr '-'
^D iL

1l':.".

- t)tlii.:l .l
i,),1, r3r:ll (5.3

\r f R t

iL: : 176
:lr': :

l!;:!i

i:ll:' ': :,

:rii: :

iliir,, : i
Itiil :.i

It! .,

iil:,i,.

L::::t.,

;lir:,'

i''

i:l

Lt"t oeE 'c - zt

lffi::/ -'],f..-({re'q) -o+,G c a -tEso r

t;r{euae punloze,r t*

nU --e-r rI --- sA- -:1 t'.tt'ia'6 - - * rrs(r.1),r,b,g rf!*,"ru-l
L
- 'i'('

eur{qo aS '0: ('/)"0 ,uiilpuoa puprncl (Og'S) er{e1a,r ulp 1""4r1 erie,r

{-n1€s op rrrrnisTral ra.rrol€.{. u4lr?n(lre1lollro1ruilueldnlr,:t"l.ueaplstuooucnrSoJor.?r oul€raeuotuyszuuoa:lr-trs}rprarl;tno7c'

tr{qe"r rsg8 e rr-r?ira(T '}ts o

-'{p{1sg11o}tu,r,o{ruJGcnToc.slr?STorlr€n;raao.r1T€zpst13oo;pr.rnJrsdo,aprdmp.r1l8f{paur;n1r u;oxric*nl,tuTe1puoe1ccn're-ttruugn"sr,.s1iuil[sa,Jq| ea'pJCooiql'ruatlunl"nlttIqslnuleocpntinrsd{epu1llfcncasIanlulJct?Trs.rr,€rnosL)g
-K+;rnc{ runr{cuof r1c rnln.ro}sizilB,r1 In.rolcoloJ oJlpc ap rdulcaloc 1r4s oJ€a uI IoJ
rtqocu rn €uorp c,il?c op riulcaloc +rrrs apun pltr,ieds FurcJES op eeunr$a"r

u1 r{trlcafur r} ,Toa ru InI?Traa utp r.ru}rJof,ern rr.ro1p1;rnd zsc lsocu uI 'ronarp
pr.rnf ur (erxegop) g1,r:rriucls furc,rr?s o1*a.ic r! (cj7.q '5ry)
ogzua.roiarur os rnlnl€utsc rourr5nrq op rrunroqo"r rourrF;rg1 op r?ztsast:1dap as 1
(pua.rp a"r+gc
TsJns €I
.i9ttnlsr6su'i(a7cI,uA'r9puXcat,lzprnnoIarn8l{o?tiau;r,irauorqrsnIuoos,'raata'p=pplr1qq€1ccauu<r,rrioooolptsrs1.Ei\lnrolet.rurrlnsluuroqcsdlrdcrra4"rf75,i1'(oIre"nrrn1aiuczr,re+qnrlcolullosaiafic,a€rnop-psoanourCJncorp'ss+irqu?rac8'lrl:4sarr,e;fo.p*caelrnou1luncfuriunrr1naKnsd,1r)
-tlu'ec E ?fi nouncurpu o.rrJ'u1 4_.1 lni e? o.r€o{t?:t o a8urlr os Fua.rp ap rruusuo}
ra.relio.rc nC 'rn1nl€wtc € c,{oprqosoll op n,tls 8e;d op aunrs{ro'} o:}_*amm os

'sol{ InFuols!zrru.rl clll ,ip :n-i^,)
IlrJ.rp rp ogJllslrJlreru') -'[i'i
'F!.I {Ts'c) e+:,,1:f
oA = 'r,i ".1

opun

(gs's) "'af ,l - t1)ogtt.r L=or

Z

orrr lcLo os d,l -- ,r{ ) 11 n,r}rrad
(as'q)

- I -',fr

Lg.r
o-l (".r - ',t)]o;r';

(re's) ur:1u*co ti (n,i'zn",{) ;Jrrlo:}fJd;
1i iiI --aollSi,egrd{''rudAcl.a1tpas€l,rrru:rllaotp,.rIrponozlos€patc3,c0uu-o,7r.1uf31ug1rrus;qrauoqJed€pul o^rca"iocpo;1lseIsnuaI1notulreq{a.?rr;iurorn€cnrTc)r
AtL I t
-'4
i
uarrtr8a.r u1 'or'fe.rn1€s op ?unrsaoJ
ToJqtii,lauIeI
1,i piulql burir8e.r o lriaoaq e1
j){:a,(utlr*,nrtn_rs$4ri;r)afulll-{olu.aar:p,}nt}lrocrIaJzoiolrJrlcrrsnlarrJ,sroullJou,]uisJI'Bunacr1ra,crcXtulog,uu,rr,or.l,aertSsl q,puocraoooS,.l1.'EFr'zJicejpa(nuJin,pleldsn,oioas;.-Irnrer.yrIgucarlts,smrl.urcoIT}oc,rc'€9,icr7st'3gsI

Introducind rclatia (J.85) in (5.S1) se obline valoarea curentului de
iratulatie

1r,,,r: T ,.r, (d.86)

t';= (l'a.ar -.-- J?o)- i i'"( l'r.*, * 2ir) _ 19*, (r" _J"_ {A*U) .

il,'rr.coo,mPrpe,ltniprtarlnliiiuriviaoi"lgoix'r.iporr*n.ie;icdsi;ic.a-lsse.i1igr.ipr,,"ionls,ir--n'r"i-ii","id,i,iia'*psrt1ralili,lu?lu;"it;dre,;tc,c1 -1f*;ri,jfi

5i l'2sr2Cz y" - l'1,; 1.,": 2*,, , {511fi
co

-zlnsut a -il, *,Co l'3ru,. (5.36',)

se obsen'i tlin e-cualia (5.36) cii 1f,f*i*i*, id.ieipiriindqev c\1lev.parL,rt<rar tnl t,ensiunii r-le
116. Se rlefineqte
x)ta'ti,
"orrh.,"i1*i;,

tt: dro i (5.37)
AI',
lu, = "onr,.

,ri conductanta rntrtnali, sa,u cle transfer.

eL, i (5.38)

!*:-----:Li
2 l c ,r.a .= .onrt.

in regi,nea li'iari acestezl sint date cle expresii :
'rmi,toa'ere
0:i z ?oOs(trrs- Vil,

9* : z. (5.3e)
i lp,CoVe.

rn regiuuea rlc saturalie conrl.ctanfa rnutuarf,, este datd, de expresia

: 7 -4nr,sat ?,
pnCo(Ve Ir!.).
(5,40)

5.8. Regiunea de saturalie

id;;i;"i; o"i"r*l;;;il;rretia'rt.d"*inicnupraegr'nealng,eu:r'lar'l,flI,nrraua.nute,rersires..iiosuarn.tui .cr"raeAtloreaaqr,a
rnai mali.clecit yaloarea de inchidere
caLd, prezen-
cunr alatd,teo"iriirioiiti : (1) modu_

puor o

178

6rt

--('-I.rls"lrilnaIrinLz.dt)IJ;aBxt' ;:orr(Ir7lu13n0"c+n1:iIuctn.iruuzoytot1rq-.ltartnl"rsr1rrirtlszclirn]ld,lr.pou'l?+oroocVrr]cu?-qJineatlol1ulllrucru.o{aso.ijo."l'rro.op.ri1,nrStg1*J.creV.(rscgrupg,luguc'q,lli)ocupe1rrlscrctqslr'uut.olt.nr';g.d}ga{€u+xJac€?tpsJcornonJFp(ragaJp?,n+tu.sg€gcIp')os+uerrEnunllsdIupialoIoEzg1arult3r.tcrossdoosol7t.qsrr1oo3oupiuoluosotrSa+ur -i
-I
elt'g) 't rr:s'1./ ./r(t"'u,1 - " il) 1"*l"\{rrl:tv) - Tl?z l\;s o fr
rr o.

'(gg'g),ursa,rtiro o1r l'up olso 1""{,T1sl."ric?slo7J111;(pob1'le'eo6d1s:nsy rt3trr op t;1{t1o21 ((
€r
Jr?]ou €-s opml (€

(rrq) , ./,(t." "-!L -" (i ) ai.zlr(t*t "rl - o.,L)X - f)z 1ts rr $ tt

r][ "'" ul (t
a
ani'';ryr c>- (g7'g) ul (6t'g) rarsc.rc{xa purn}r+sqns

(url')

("#) ','; ,DS /r -, (-,F - ,):'{ ,csor - (*;r) : l,'|sc,

?,. llllnluur3o r,iutrlaupuoJ .R?,l.I]orl acl ptrarlde eaumsuol op OIJCS

rs ,rolcnpuoc
-{rl{as-prxo ,t;ieJ;ro}rrr €l np,r?rrrc.lqs ilp ?V m1 r,iuopuoclap gzuolgFou oS

",tii'c) '-,,[ ,,""',, -%,r-7] -

t;iluuoe.ixl clso,lT 'llsrJDS rr ol,uotT i* rouo.rp ,u gltrdrtTs '1JLroJ'RS cp rnrnr{3o.{

'ar1u,rn1rS op rrdrprroc nl gui),rp op Iullto,rnc olSJ rn"(iJ opuu

( {f 'e) *'r?rlqv) -! l"S rt/l,

tosor

;)j") rn{nirro,rnr r;Irg.r1a1] ioar.,irt,,llsrlel?,r)rronrpli_rrogc,'Eru,\i.la,t1p,uosprrrrnunr.lSrsullrlloll3uo.ara.rpaFlcioslrnl triopuE-ruzo,R.ttps
n,r-'urrJ[unlr]r.rlr1natTlr.l"reiuptrT1rnr'ltllrSlacrE,,'Bnrlapnl.t,illruragj'teropaulls,;cLurrll::z.o',tr.,urco!,lnlnris.riJars?.rulr{ri{'nroRscl?trcac\1pr.rlrlqpnrrJrrrtroumrprrrr)lr"pirSrrrnrlarlo}ar.oorlclrllticse'oru{nuililrorlrrn,r;t8lirumt.Jpruaqt,?lrBla\Velc*1aK*o.tearrceca.r?,fcrnu:plrtcarsoKeinpeopulunnifJlnler'lg,luur1ziulor,>acu.7arrStnlsVsonror.s1.{rr1u\cl-orrplrrnolqnlsrctri_irlr1r!

pul.tp n'1 ayt p'1nt'jnt{s nutcnts ap .tt,unr0at 33unrsunrba 7t4ta.[i4 .i

", "jlffi.!t-r-rlpli,crrrhilr,rt?nlitoliuutt*rutiio)rr.r,rcltaspr)t,rrtrliicrirn{glurrs.-,r,qtr,nrrt,!.i!''ra1orap,i*r.1aqrn.r)r1r1ro,ng0rlp,u8,ror{,n,rugtElcscl;upraurrprc,t,rr,rEu:isrTri,toHro.p},iri:i.l1$},ns.a"co}",roHir1upc:ra'lr"nlJ;oiuliniar;lr.,tri:,.nu,rc1uuer:cr*,Lr:ru'nBn(5rr"z)r|a5!l,1rgrror*nr5.le,,l,trurl:aptci,(Trgeu11)

liliiri cle criti'e l[r'gillea stratnliri de siu'ci:rii spnfi*lda1 clt'enei cste clomiuant
i:r ,.ra,znl cincl rezistivitatea suJ-lstratnlui semicontlnctr:t e.qte na,t'e. arlici,
,\f, sc poatc moclifiea senrrrificatir- cu tarialia Ir".

2. Reucliu electrostaticri cc cimpu,ltti cl,e d,rend, a,sup]'(L canalu,Lu,'i

-\c,:sl, efect cste doruinanl in stluctulile cu substlatul seruiconduct,ol
de lezistivitate de valoalc rneclie. La o lensiune cle fueni, rrrai mare tlecit
r-aloalcrt, de inchiclere a canalului sc realizeazl, un euplaj capacitiv intre
can:ll ;i th'en:i prin intelrnecliul stratului de sarcini, spaliaid, al drenei. I-,ini-
ile cle cirnp clectlic (fig. 5.45) merg r1e 1a drend, la canalul cle conchiclie.
Cu cre;telea, tcnsiunii de cb'c.n5, cre;te iltcnsitabea, cimpului electric intre

clrerrir ;i canal ceea ce concluce la crcitertrzl nurtri,rului clectronilol din stra-
tul cle inr-ersiune c(caannaallu)lu;ii,rloecpi olal,timunicegotloarteranraeizmisaternetecilinaccesatnuai:rl, I cu mic-
:ior'a,r'eir lungirnii cadc sulr
influeri'r ir, cimpului 61s 6hen[. Lr acesl fel tlrena functioneazii c,a, un al doiica
electlotl poaltd, cale contt'oleazir contluctau.ta intlc sulsl ;i ilrenir,. Yarialia
tlensitir!ii de sarcinS, pe unit'atea cle alic clin eanal e-qte da,ti t1e expresiir,

{Yt- -_ c,d\vD (5.46)
ZL

untie Lr.u csie capacitatea efectir.ir tle cuplaj tlintlc carrir,l;i th'cnii i:i,r'Al-,
I' ptiate
esto r.alial,;ia t,ensiunii de tlreu[. Pentlu. AI' < se consirlela ei, cimpul
canaiului este
t-.lecl r'ic in tlirecfi:l y :r

E: 1'" - I-" (5.4?1

5i viteza, nrettie c1e ch'ift al electronilor in canalul de cortclLiclie a,r'e va,loarea

Ta,: v,(l'c- {'n} (i,.48)

3\ .e

. j. 1' ? .: :2,.; ',7

trrigt,le5.4u-1u. u- i C:rro'r:tei'isiicilc nalc Fig. 5.{5, - iiealtia e'lecirostali':I a Crenei rsupla cana-
tranzislor \10S.
iuiu:.

180

taI

il.i!ir) 'rt)IniLir.ir.t u;.ru-rc;.rod ...]c-I.$:iit.r.q!t: l nJtrilod ourf qo og .,p1ur,'i,eris uni.'

l:ir r(.!ii ltr,ilrj!izirEJ.T. .,5I.,I o--t,,irrtc?lsm1aS. {e}H8}-t\;srlJi+iBclFua{.I3u,orp€+lcnsJr?iu?r.drIlloosolpxT,o';i,r1'lln';p1lsurg;on*.,r1-
-:zBa,iJ rjelcalur luo,t ]caIA i qua.r1:
!{'
r* gs,rns oJ+r{ .roylror?colo €a.ruTorrnt
\@aiE.t-r-ir'-rM^'rytr4 -'t"" d t
tL\t Lt/-./" :E:i;r,:^-,t;c' -., ca*+tolr;l{3t oFuJ qnor+reseSK.?rSnKcuc€tcsuGgo)qq.rF)sqrouicrgolsaa..riiidr},s'.ulJo1.otu1tauu.rrr
/"--r--...-, ^"i;_.,_.-.-i!l.,r.-.-_-*--_i,',:_.--___._\t,i.r,'_, . !

r1- ,---- :I:
'';--iFt1l"-:-t:'Im-r'
iil:i:

ii':'l

'!
llitirii::l: t'nci,r1oa1etp aJBxq?IaJ t1l ,.r:- 'rnrtntri.
r, liiil::r irci)p aJuur rr?ur ai"-o tdull,lhr, .rol

!i::,

iji:], 'rrFuluronrJccr,lrc'l'lxrsl'o.]J.rrIr1)r'tI1qrrl?-r'ftIlrg[uuJtrlsrltn;urKrscTr:lrr.urrenaqriSrrl*lF..iarrTric,islr.l€r*EoDsc-r?a-;puL-'I".r"'oF|"pr;.l"ur4or;lg.oHirpn,rruilfi.aje:,r;i,l;ii,ou''.,r-la"u'f?esraa.u'i tli:,3It,lt,r,rTitTrlsi;
il.,i'

:,:rrl'

:il:r.'

ri':1,:

,.4,.

l.:. (ac'r') "..hrT - trsrf_|tr - o-l1 --t,t _1l

'l: riKlra'n9rlsp1rlu.rrJ''nn1u.rsR'aEUrcsar.n.rprrizrll,ssrar'rruiurlJnadp_r7sl.rb1rVipi'p{o1i;arrdnFrlunSi,ltis.?.lrrTuiqr1repoa,srlJJ:dnllslaIlI?(oJZSp(ro(tio€.,Jgr.prl]ur/t)snisul..l,rrrrrrnor-,qritJs}sp.i]lrrasqolat1adlsrtgtr-lrlo?nuieq.ullrnpdoac}_Jt{ropro.ilo3.psr,rtiiucEcEis-lallrqnsx;I,nocBeas(Jo?ioaJtsusJluoe,cnrno,or,]1rtccis?cItl1s?uaars^o,p€slrfu}so,sictq)lrln\uzr/croa.o,ope;rJprrlEKs.illcuccoe'.n1:,t;2;lrpiji.{[,r[lue.ilriruo,sirearapc,rr€l6r,ls\]p,

pTaSfnrls nn.tclns op ?ptLluLl clJ?caya Ttlua.u?C .E

a-u-'tr+u"lJ"td*-re*re'Tr6_cnual+clnirulcpaauaro6lcxppanofprcTcrruyr.ro,aua.ctlrgruSBilrJru.nc?.ro'er_}pId+an.irmI..nro.trsluarlrocuipna[1,z,'r+nn:r1s1]odporlnoc_ocd+Ir_teusn,ouulrnup.frDJ.rt-r{csrJrlret,rr.u+anrE,rorpl+ns]rBpqfceieooxldddoea,nFcSucrao'iIr.lc{rnr+r]l]runscerEuppaalil\,ire*roliro.}lrbnuouapdXlarsuIxua€.or,io0iFu};r);a,rE,]a,,tai"pse.Jr..5]nBri.ar8]t.

{tq'L') , -T.Z{oC _- tt'-6

h;AE

As ?tsat ?.trun tnLrr t:iuul.ttrlrrroc rr;llriad (0r'c) rr;i*1.r,r ".rrnu-,*'ii',*frt',;),]'" tttt

{oc'c) oag

(u-J _ r-l)tcCu.rl '' +rsor, -

ni ;er,iu,rn1rs JI] u; ursalc{xe ap Tr+rp a.}.ca

lliJprioc olstrc.E tidunr$ot rnlnl,Ern?c efr.i'utcnprro )

1r;t 't t (tj - '-1 )urlvt'''rud ;g lnt dIV

J[l ltr]ol rnln]uoJnD trjeerl,srae-talErllu3a+Jsio) .ailJpailGltnitrei-rTiicr,oula.ur ,F/,}{'eyJoclur{p.er*.nlr.,ol -orv-n.;ur}rrrr.t?.r{1Tr

clcnsitir,tea de cu'ent electlic lirliitat de szr,rcin:l spalil;,iri cli]lles;il,

,"^ fle"'r,, l';]
s/,3

I)iagtama de benzi clc euct'gic & st,ruoturii irL concli'a,ii1e tui'gerii
limitat c1e str,rcinzr, sil:r,lialX es'te leplezeirtaii liL tigttt'll.
curcn1ului-electrie ??+ separate plintr-o regiune p de vezi,stivitatr,' luare). t
5.4? (c1ou5, r'egiunf
Our,entnl eleclric lirnitat dc sa,rcina spalial5, apa:'. in ca:rtl cind stillrfratiil.
are rezistivit*te mare si lungimea, canahlrti cslc rnicii. I)ctrtnt tlatrzistot'ii
MOS c1 substratll de rezistivitate n:.icii ;i ltutgirne lna,t'e i:t c:iilrr,hrl-'tr'
rle perforare este foarte lna,re, astl.el cli irirliut<ta fen*mt'tiii iui tlt:
ten.qiulea
perfolzl,r'e aparc la dreni, fenomemrl de strit,purigele in avalan;[.

5.9. Uireuitul eFch-uivnaelefionnt aarel atraIuazisintoanlrtlui ifrMeeOvSen. fAil nrillil'iearea.

in figur,a ir.48 este prezentat tra,tuistorul l"iOS cu elemetttele tli-"creiir

Ddtdsleanei,rnnttsect5t-ri,ar-cebcs-cupatdle2iiotor5-aertc,le,anat(ptsr:5frielobe,-qszrcpmitearo:nsnaattuatat)fbli'ti,,siinCatCnlobs:,,aorr,f,eci-tg-,iasu0tucerscraaoasf5pp-ir,eaai.;ccc4iciti9tt:iaslla.lcltnt,aDieebca1aisoi:tto,rrdapjarer{tote'el,ieauna(rrijr-ttoiDI-p.ns,a"oc-u,ca!b$s,lirritsiteLrDit,uuln-'aaesici,t,ut.uDsrCCsli-in"Liii,t')rt,,c-AeCuPcloiicae"tnauts-,iplntr-ltl*-+rtart::ai,ct|sriaphioiatitneltlc'taiat:ri-t-;l-'

--t Irig. 5.,tris'.r:- 'I'ranz-istot'trl ]IOS ttl c}:tlrentcle rliscrete
sc asoci:rzi circiritltlui t'chivalctrt.
qvo

D)

I'ig. 5.47. n-+-lp)i-ang+ra)ma acccllciilibberunz(ina)
strrrcturii
si iu condiIiilc curgerii ctlrcntului
clcctric iirnitat dc sarc:ina spalialI ziri.s'1t9o. m- luLi,iIrICcu-)SitullaecslieivraillneatrlLnaticl .tlan-

iD).

782

t8I 0 t_t saol '-sJ,- -1- '{ "f -i t,l -^ ]
i"*i
(rs'e) I'
1
,t i,,l'
.-f _ 6{._' ri i
& Il

KlrccrJ1€ur ?ulJoJ rlris osrJos IJ Xod ;ri1,uri,:t Jq.soo1i

iuS'l) 'o:Ea /-tr , *'.-t |l -: ,.r*[i I-(T., t"i)t-(

\I

a_-,t : (En, - to)t.T i- tctI
a

: tiTIi]{i{.rl

oS fl lri I- cllJixpou ug rjua.rna n,riuecl Jlorlc{.rry tn1 e1r5.r1 i;t4c11cly

. apCc'r -i P(ttr t

l-

(sli'q) tobpot:zT

'ouc'I - -1l:"tt

: rr,iulou olo,ruolpluJn ri uo1.ro_!d lnl uuroJoat lluis
-oIoJ q 1g'g e.rnFr; rrr uc 1t?+uozc.rde.r r; eluocl +InJ,rIc qsoo1* 'D ll'g trlrtfirg uip
.'o-l-ntuu,r;rrIoo(rionaa+l,:urc,snrgnrln:rz,l1prqua1uuco,usrorqlarcaudepr1IE.on,)lrlnglragrnfnuu,nucc.nurJ:rotr5rnr]lccamuC,ourn'cpI"cIritquJlf63laao?ofrlsuauJ'grcnr€zcnluos'fpuoiu,o?.rrro;{s.rn+ce1rFeuprPrn1p;ur1uipl'l[t'Jiauaprrcpa0o[lI1l,u1es1cEnar1z',Il(J1uoa''ulJ^Ip?Iir;noqtl:dtaclnuo]Tcuutz+&rwttnr}l),tooluicnxtsdlgrlrrJutnrolcaDop-lps.oJrl:luIaosccu]garl3rt|u?C.iricco,\t'riIll.2lcll:tJ1.18lltllalS,llrr]plnorlOlonr1.iIlet]J3ltfii
lrrorl,srrozlurct3rrgl lduunrr+€Xluzvoaz,zorlltdt3rcrrlsJaasepau;rnuc'gr;grld'gurte,rno8pr;Inu,Ito+lcu+uTJrarzsapJ8dat.lr nlduit-i Jrlllrrll
nr?uod

(r!'s) .oa*fr:,_ :"(:t;) :,.ui^('!,; ) :,rr,: i

GIJJlJ

:=ca-co=:,;r1:.1)uutsuAopodgruE{oOcissuualona'frrJrdp+xrsono€ap1p(IoonerPprn'l{c4lrn+ium+rrr3eu;pdotaepo.tnrr1.noors1rc.airuiou.rKapl:scrro{ria'autg.lrr.ueprr'uIrr:otaupopouolrulI{l.nesl\11?aasu' lzas'Ele,llor,tdrn.rrurct'opio(1ac{g.'.tilnr?uoaoaulcgpreIlzulrosuropnaialctlllollusscaan-,u1tJrt-azsoarllC.lprotrus+a'r1nrao{uec{z1Ir:?r,u;rr :r,trit(.o)Irrg)yraT1isllti:iri-1?;r

-rJr3A o t.,1 nc rrrplolt "Kzqaaurrn ac oloa urp psualo{u1 tp eleocl us ullearltuutag

o-d''-1oJtJstaa+auo1uJau*oo+p,$rCpuuF:rr3lIuo€o,SqTupi+rIBnnerrou+lr1oooBunJ1FoJn€caslSal1'rrcqS4o'tn,"3O7opSdC'Iusl\rncsIIiJ)C*oenlEg"l:l,'Sso5ur3.1a+rarJE.irS?ro+po'u?ro1oIooC)trl8'cd'aisplJurel€grq;l.aOcnlautosicpedpa4eropcFdelru+u1urltulrn{ogtrlctlunctl.rllIJseirlirIcucznoo}tocsJcSIntglT'lcl€lI'uSofJ1;Fturs+ron:uo+l]IosstSTlulrisalptoto*tptr+r'olrl?trlli;nolpt1ltq'pr1c-ncsr3o3o,'1rranlsIlttnr8tl]-Ial]"1illrldnl1:-o)qrcBa.luIz.l'ro(paI;tlF;t.onir{i

!R^
t '-n |\e-,-+i-P-,

rD

Vn-Vo
h)

trig. 5.50. - {lircuit de amp}ificarc cu tranzistor }IOS (a) si caracteristicilc .trr: i(1-l);i

elreapta ck: sarcind (D).

I ./ Fig'.. 5.51. Circuitul eclu-
;lrnplificnlolttltti
I r':rlerrl rl

"p V? c,n

*\

/ /,/

-

I.ros.

Ilefininr niatrioea -}-z (5.58i
(5.5s)
}i *Y' Tt^lLl-,-1i _L

]I: -Y, * 9n -R"

al ctlr:ei cletet'rnina'nt este dat'de expresia

A:(Yr -i- v,) {v, I"(- T, -,= 9,n).

184

:'li I

ll,--1

to : t-r

,i)') ]'-- _ =r,I
t

alf j i,!r lsrza.t J,tl-t :rit l,.r}ls'L: 'i;)riil ill I Il{iu['rii.]ir iulsi t?,;1 , .,, , tt" J l:1 .).i,1: il I
il).Li].il;-t1U! rl.tllJ lit S(ilf ,ltli:,tzill].i1 l:tl ;.)

irI-li.i'lprr-iitl )

igs'r') _:.{U:tfultsli , _if
|'
it't'l't- t
i>;

'$ ,t -. -r, ,t

il = '.{ -,- I .[

':iTII i(1t} '1r l',.irir.3r:ri n,t rnta'rii.r; pruriil5erl rtsuoi i. I t.r_.', .l -i,1J,!l.l

if e'!') ' ,tit li_:,-r11I-\-. .t : ,,-

;_._, '

.)-fir.I;-iii) | iJ

r'ri , I

lrtsi'r.ltllJ,rp r] i]lJ)

:-O r- l i]
\-"

I I -i

I ,l

i ,\ r'l

rfi'! l i'! i,r, I i,t.,

,L I - I i,?,'-. I,7 JTLtT--JLJt:

,1.

')llt r{i(} ,r\i - ?(l ll,r (it'l) r;rir1,r,r tii;r;tiltIi ilnrrr

t-? u- t

i *rt',: ) '1r ;- r_-! _F-r-ft- --
{1
-l!- I
t

trJ.lr.i |l?rr{ .lpirLi y I{ I{ -: I al.u iitril !1s, Il i_lt I l
i) I I Ir\r;-

se ob!,ittr:

, + I(R,
-ll,rRrRo * -{0. 1 -1- icot'Cin,, (i.6 i;

liu) (1 -r i rot"el,." ) -

,lcerlst& este valoarea a,rnp1ific:itii la fi'ecveni,e iualtc illi]. in plesupitire-
lea {le rrirl,i srls, lreglijai:ea capacittiliior' cpsairrt?}iiztintcit(itio{[ar,lLtl'0,tlrnitpfauol,r fi'ecltnlri.
funcfional'e a dispozitivului
nr:t,rini"l tle l. ilr"ltal-
zit lil plrl'ti1:olilot' rlc la, srrsit iit, clreni,

L

nnc'le y- csie rnsbilitlr,.l,on purtir,lrr;'ilqrt'rlt- sl,i'cirri. Pt:sio lursjiutcir rio irichj-

tir.l't'. l': \'e - l-r. it

.t]_" -_i',) ':'t ;.{i1t'

TJ (-t l:L

Ireiltlir, ca flecvent,a clc fuiic!,iorli.tl'c si,"r Iicl cii, ilrai itlrto ircl''iLie sii:e lillo-
scascii, nrateli:r'le (ca sul-rsit'rl,t) cu u.lOIlilit:rie nra,i'e :r l)ur'lritolilo| qit' i:t-, I-filiir.
sX, sc lealizeze o lungitne) -L) rniczi li, oanrl,l[hli, Lrc(]rlsta,tLiurrlmii ir,,jgtilirirt
o coriductan!,i, mutualil rrare ',ii o cltir:rcii:rtc rnicii, a, c?l,niilllit:;i. rle trse-
rnelrea, sir' seine1li:rrroiicneesrcii:Idireaclritr;eltpile:lt'ptia'ci'ar!zliltecsllrorrpl,i'lii,?lp1-ldirI'ccnlil"ir, si rirlul"t-c'li e1r,i t)r'il).
a,sigrirat'ea
1'|g11r'1111111r-r i ,t,'rr,t'1 ,i

llesle llot'lirrnile a,cliaccrrter a,io sul's()r qi cirorrei.

5.10.'Iipuri rta tlanzisteitre,iIOS. (lolreetarlir tl'iuizintoarelor

irr. e ireuit

Exislit, tlorLii tipirri dtr 1t'airziritoiii'er l{OS: cli crlniri uirtrul;i (.1 {ranai
initial. Canalul poate fi cie tip n sa,,t tlctip p. irr tlurzistor'-Lil r'u car.:rl lritlts,
\itcr-izaoprnzloLirl&r,',iil.uv'cSilre,atlscattieetnunisllsli,scullalebrrtsuiiintlrvd'daree:1lspuinilocl'erearsl,tpsieliaierlro1gienattdlleiirplrilsrrpp.,t't;o.'ilinrtlcnarie:,rtpsgiliieucrrtinlittra'i-etliell)rlcuertirelr1reci.i.tirlttlreciir-tL,ls,s'ritril-rrn;1tliiupclrru.lcliil-'ic)gc?iic.e1l,a]irtltl,ri,rrr:,
cttl'en1, prin ca,nal. Pentlu I'ct { l't, c,trlcrrtul tle <LciLir t'sia pi'ar:tii: egtl
ert r,ero.In tt'nnzistolrrl cn cana,l inil-iz,j cxistl rln cii,]ri]l r't:rrlizat in }r'octsrrt
cle fablicare astfel cir, chiai'la polai'iz:u'o zerr'o po poiurll"L r:nrge tiri {.lili:r!l
intre sulsi,,si t1reni,. Conclucti-"i1,:i,1 cri, cilnalLrlui ct'e1ie crirrl se aplicri irt:
poat'tL o tensiuuc de setnn c5o.5n9triis'rintti,prr''c.ipul'iczceleirlct1ro,tlerrlnsctllrir--rcitl,uci'liule:rlcuuhrcia;rir:rr;lciartlir-:

iu cltzul invcrs. In figuiile
tial sau incius cle tip p ;i t1e till ir.
in circuit. 1ri lr*t ll;tro.l5at4'izisri,riL'e1, ze\^'o rjr{}ct1}}l 1i sirirlrolunl,:
folosite figulilc-5.,r,i plrizGnli1,1 ('(fr,iacliei'isiicikr
Itft,o"irat::',.r.frefl((stIlrtI/eO,r",a))Snac,fs,iuilo1Igrc"'ta:i=,nf-pa.(fe1l(Idn,'('ec;t)ltl)lipplpet'ltaretrnctinlizt-duishuttrs'oa.srn\ilrrzljcigsielutcoulrirrLiicrtt.lie-.l'}inre.IriOilrl"rrSdl1oeie.'r1ur.5ii[ptcsi :r,rpieurd,iilreilr,ula[rec{ialnnerioi:atsi.i,(rcuyrtl;elii.1il:i'r.rS1iriir1,tizu,cizisflrt-i:-r,
pola'r'ilitl,ile tensitiuiLot'sitL'c inversatc,,ri lrt cari<ltic(ic i;a,r'tir:ipii in f ilrrlil-,t}

i86

t8L

t-'-ol'..'relt,jrBtu3cl,)l+roqf.rut'oatn1_parliaulart3oipi'iet;io,grg51.i;rI',u"luigro,icrjsd]oJ--=r]1slc\,1-"t&.E",t1l...rii:n3lat"rrtpti-\lilJir.oillofoI..rirl)r-rr{ijti,sil:pr'r,,l-idlrslisririiolrrc;{Jr;ar!rsnJnlirli-rnirin(iilrJs-.1irIl+'lot3iJF0r]:1!il1,lini1tii.;itrrli,l*itBr1iI;orto,irlzitl{t.rjlZ.ir,tJ.t'i|,iqli}iorJu1Clar.r;rzrz+

'lts]lrlir illi{llJ c.l q0l{ 'r l) .i; J) it rlr , r;, ri i it lt; r ; rJ qr, :
nlln.IolsrzLru,i] u -.:1:t..oti lp ilrlir,ill ,:F t7.i ri rr,l t]ifiLt illiu.l f(
;'iilrr,(riJtr-IrrJ.rl.) -]tr t{tJ.lrrf, rl-) ,]t /t; 1;[])tir lc|,f.. .t.r : {( )t\ iJ t.l
ir.,.Iifi.rJl.)it.r8')'itf't j;1.,I t.Iilrlt
i..t .--r p:.:r , ;ir
..

'D ,,- *-j.- :, : a /!-
!
,1.
"*-- ,t:-:'1 .. - -. ." -d" _ --!_
9| n
,!'
FIitt4/"/'
i' | -.t
-f fl/'/ttl,1A."li-.
*---;*' --'' .l'
-l u v
\:
vuu'|'h Y

lI i8ric.) llJ !()l\ 's rlpLi i l'r !:l.rll{,ii ,ri) ,ril!:

Iillil.lolslzlllr.ll
-rsiiir:l-ErrJ.rp ri) "lLr.lJ11) lrJ{lsr.r;jrt:.rL'.) - T!: q 'ii.,I

<-gj A'eA

--

(t

I

a"

Yu:'c

'-qnpLlr i, rI11 ,rir 1cuc.r rt.) S Ol! :l ) tlJr) l

-sl7tlt-.1I Jt{.1 Il!i.}.lil Ji) .l[l;)llsi-tJ!.]U.rU'] - llf,f i,l:l

A' cl a

ii, f:r\-':

Vti a ,] .. n -/

TI
r-L

! i E-ll',+. f.- l-J '

-'c . .t\{1ir..,/"ti

i

t>

i?ii!t_. - 'i <.
t L-._, j

EFgSDgt'rgp.rB-rl-l'gU(lgrrrC'lgllrrlriolonlJu'BnorSiisr,rJansitr?l.illaE,),J),tglaaa+rnfriiLl ll'r?rxa+itnlrtrrr))o,lJrJl)orl,rii,rur1lrr"il.,lrr!1o),r.tllr.JrlurRolirtr:ilruro?nJ.r3iIgilti1pJLrlr]-.<rl]o;i.1z]alU]tlri]til!lc;,lJ{:.)-.l,;l)r"r/.1tr?rlq1r1,lr.olrili;'

Fcs: tr.cs- T:", ecua,lia' t5.32) poate fi rescrrsil

zlr(o f --[tc"(Vus'rV*"* (I."t-1- ; ll r')2

L- L I
t:l,rt- ]'") -- V e"

)

- Z?,,(, 1L\1' v U^J^ jl1I .,I,'J (Yo* - I'")tl. t5.?0)

-

'i,i'' .lti-.--.,t E "'ls j' ;l.-

ii-;,c#F-.i i i
ill i
I
'C'5 I
.
:-iJ
s

Fig' r. ;7.-{,,-i;riisuralia,cuJlT,:;.:,1iii;3J:' n, c,i poarra ee,nnuri (D) a

Aceasti, r'elalie c-ste vala],riii inainte tle satula!.ie (incJiiclei'e:1 canrr-
luiuii..Conditia cle inchitlele :x can.a'lnlui in conexiunea cu poarta /('{rnur}ii
se so|re

Vue:To,, - l-c,s:(l-",, --t-") l'*r:Vr.

Subsl,ituincl :lceastd relirfie in c{ilre.7i0e);islee obiine o relaigie identic5, cu
(5.36). Caractelisticile de intlare qi ale tranzistoruiui ,\IOS
in
conexiunea eu poarta couruilti sint leclate in figur"ile it.58 a si b [33]. Din
llunct de vedere teoretic cara,ctcristicile tranzist.olului 1VIOS in configLrra{ia
cu poalta comund sint simetrice clacil se schimbX int"re ienlegesunlesraalEini drtelanan,-.

(Practie llu se intiltplS, a$a deoarcce electl'oElul poartd,
zistorii cu eanal inilial acopeli' o pailiune clin eiectrodul sursd,). Desple o
asemenea simetrie lm potte fi solbu, itr tranzistorul cu joncliuni legat in
coneriunea cu baza comunX,. In figu-i'a 5.59 se preziriti, c1ou5' circuiie pen-
tru riclicarea la oscilograf a, ciliacteristicilor Ir:,f(lt'""r) Ir:f(l-s,.,)
tranzistorului -\XOS in configrLt:atia cu sui:sa comunil. Di ale

5.11. trnfluen,ta tomperaturii as&pra earacterist!eitror
tranzistorului MOS

Din expresiiie (5.32) ;i (5.36) ale curetrtu-lui de <ireni, r'ezult5 cd, mi,r'i-
rnile ir, c*,rol varialie cu temperatura concluc la o modificare sensibild, a
curentulni sint tensiunea e1e poarti Tr, qi rnobilitat,ea p a purtd,tolilor cle

sarcind, ctrin canal. S-a observat erpelin'r enta'l cir, mobilitatea purtXtorilor r1e

r dr)

68r

:Ir- (n) (sgrl)/ r'(q) (sr) t )r =_- or - '6s'q '..'Iil

o7 ;o1rrr1sr.r..rl.ru.luJ 3u.r8c1r;'-so r?I ui).1trst.rJJ n:;uad c[r;:1uo11

(o

k

-B.radura+ Iruuaurop ui SrEI rari,r2d un acl BJn+tsJorTrual aB E+uapuec{epur arj
-t?uriroJde alsa '/strJ 'g1e;,ia1ur EI ap lrrJ trurcJl3s Ic I€trrslrrrJacT\a ;,clruJe e-S

..g"A?-6-: oO nc ='sQra* -="J i

{u's)

'T4tr,-=,"h t,t ETSA.I dxa
ap KIB{} a+sa osrrTJa'lnd iarsJaaul ?aJ?ur+qo llJl.ilorl t t.8e. _it^tf ep €ollnrs Lr3&
'II llJu,ior1uiol €aJal*aJD
I nr ,?ua,rp op rnlnlueJnt eaioprls riur.rolap iitE i

l'€ lr tt i.rl o I

t;trlcod ur r,:rjulnFlllroa in -SC'SJqf'qrrUl'lS.tto..Jf //,,,,T^1,0)rj
-s!zirE,rJ JliJrlsr.ralJeJE.l

iq ,(o

,,,'{Jt *ton) ," i-/ '/-] n"
: -1 L.
9t zt , 0 ,- 9- Zl-

.{f.f t, t i il ,./1
1
,y' /' 1'/ |
*."--:F'// i-*.-,*-.--.'-ii I ,1/t/,l -1 0! c-
"-;=*{ ,tl,
\,{ot _sea) a,
oI4nh)|t ) -l 3 j.

\

a

(ctfzrltt) /ot

-qrqo{u €aJoprcs 's.rjt €a5ol tsdn.p apecs ra?r+rlrqow oll€q jeur rJnlEJodrual
t'l"gTg'r-_,gtrg_]nuc.ronpllu?r?asd,€ruoo1tls}€]{arJqao?rSua.r3e .n!6c lo+p-"9JS9-rnglnJInu?{er€JcadIunrJao+uoa+prnlnmluopruluorpcJielri

t'.rl'iloi'de hrclri. ;i +iaci se presrllllnc cii qi {D,,," oste inclepenclent de ternpera-
tuli,, rliferentiind
ccua{,ia tle mai sLrs il raport cu tempelatLrra rczultd,

_tillt-. -_ f. t_],'_..rtL I a9u_ ' (5.72)
{,u I Q,,
L- I d?'

trcrLtlrL rrtL canal de iip rr. realizat in substrat c1e tip 7r

1" n1 (5.?3)

{r,=-:'u* hrifui71,1.

q

1i111lg ri es1tl colrc.rjtrlratiir 1)iLl'Li"ri olitror' .irrtrinseei clin semiconductor,

ri.:3.8ti . tr0161'r3r:r r::rp[--U,.( 1'*--B)!Z\,T i (5.74)

l)rirlllt siliciu i En{f'..- 0)=- 1,21 p\' ;i

icr'-t-1-l-q r",,\{r1,",,t1- tq.7' rrl"i Lir",,'\,i,.,\l1l-.1aqLfu'o"'f\l,",,\/- !'t({:9- ter-l l
2t;T
,t

in rtonrcrriiLl tenrper':lluliiol rlo lirclri, ]tsi,a{ :0) Y l3/lf ;iprin urrnal'e
ri'r-itrtL ir vedele ir.?:3) -\e poatc sclie

_dr'ol', IrL{.=,',' !,:llq-_o) jI' (5.?5)

-\s1fc1

t,-_ 1 1y:,",, t_-1 -0_l iL," _ 1 li/lz5?a.at" l. (5.76)
)r1 _j
I_,ijl '1' Cn J

ri,ierir;.Li:1, iensiurrii dt-: pr:i,g in lapolt c,n terrrperatula va avea toicleauna
tranzislonll Ii{OS cn canal de tip ?l, ;i sernnutr pozi-
r:ril.iril;1 itt:gati-; lleir.blu MOS sn canill cle tip p. S-a gdsit experimental c5
cliailniaaLr'[tlet1etitpemrzpceirta;tiuprXenintrndocmeleencinulc-a5n'5a-l
{1r- rr:nilri tlanzistolul

T'n este ir.,proxiruatil o'Iuiictir-' 125"C
d.e 1,ip
iitit peli,r"n dispozitivele cu
7, 1.r erenrplLr esrie plezentilt in figur':r 5.60 pentlu trauzistorul MOS cu
.,i'lllt-r,i de 1,ip p.

iu figirril 5.iiL este lepreze;rl:r,Ni ccnilucia,u!a can:llllui

h=t::"\ t) -''::l(r"-rr)
\.( t lt.II
U T',1

irL functie t1c ir:risirirLoa dc 1;o;tt'ti,, 1a tensiiine t1e drend, ega15, ctt zero' 1a

i,ei iarnpelatLrli rlifcliic. }[ic;oi'area mcbilitii,lii duce Ia micqoiarea pantei
rh'eptolor (ctin fig;-rd,) cir creqterea temperaturii iar creqterea tensiunii
rLe prag cn crcqtclr:a tempel'ai,ui:ii se obsetvii, plin deplasalea punctului de
inrersecf,ie a d.reltt-rlol cr1 Axa 1r:nsiur-ilot'. O moclifica::e asemdni'toare se

1'90

lf) i

')3J+S{lrls-r?S,InS rullrsUO+ rOUn €OJ,rlc

-{i11! ?Jui-oacrr i)}s;l rnlnlvllll.) rari.luprioi} ua.ro':.io,rc nJ}{Tod ri ol€ru o}ts}TA :
-lllrzcJ ap rI cLi. all illsa InluJls{lnS .rr:r (lclirur?, [r?ut??
11r] SOT,{ r.rn+cnJ-}S cSoS i
-uloJ os opuu eiuiiiirp alur5alrr: SOI{ oTOirr}c.rra rrr qrnu*rqo polu uI pcr1t{r es
.rintisuo+ Barrolirose {) 'J,E.r}sqrirs ri ps,rns o,r.}t4 a},Bcrlcl,e irunrsuaS ea"ralia.rc nc r-
'0riir-llrssu_o1lne,rlrr.mirrllu.(r6o1d'rgir)i))r:rsiLaJ;ral,rvi!c-i.r?uI-\aacnll p[a]l,lr,re!sJ ,f:l.JosQo as (l.l.g)
oii'uJ.r FB,rfT a1) _
crslr.idra f lstsocl--
"ci,i"cnl;a 1il1J i

.*i-t_"T--7r-- -t

'aJr.{J.irp l.tnie.rlclLri.rl r;,r1 r:i "r/ 1uur,-.;
-iurn.Jilr'iilsiill^sr(.lJi)JI{:1il.r;roj:)}rsr{1'7olr.nr.1J1ic;,u.r"oJ*ruuiJin;pt].n-Jr,.rlrllrr:ri.)a1rd:-rl-l"s'yjtgii.rilc.qoutIl'ir-l.I;i-ir-.rIl

-r l: 'ol:

3-

' illlill.i 'r1 .{t t jsl;iii8.rl riil
ii.r.lu :tl riJ '.;Ol\- ll.lj ll-l.Jiloi,i
t.ttt l i:.icdir:l t a)L-
?"7-
I l
.i1r ili]ltislrJl u1ltrr.tt:-1. '{ii} C 'ii!.'i
I
v00€= P {('
lt"_ (a
-._u) 5^t.a)Lt y t = lN
i1.-

I

.-' -llt .1-.i. | ,.r,1 t'i'7.'' (] :.)- Jt)
(r:'s) I ]"1,
i "tp
l-p"f, l_ ;
,-b"" q 7l "

ri1,r tslriJoJ eludua

?tiripoui os (6J'gj ,i: rsa.rd-xe t :|'1l,Ils Qns e g,s"rns o.r1ur "r1 ounrsual o "garldu
Iri3{t '[gI ] Fr{o.il)
ap .rolrcr'lsrJo ]rr?,rBo erit:,rril,es op,r:aunrFo:r rir r* g,r,rasqo

5.12. Alte tipuri dc traazisto:lrc etl efeet de eimp de suprafa,ti i
(
A. ?rarisislorttl 4n care cotttuctele sat'sei ;i drenei stnt bariet'e Schottlty
':

tn locnl legiuni).or difuzate p- si ti- a1e sursei qi drenei se d,epune peste
siliciu un stra,t sutrlire cle P-tSi prin sinterizale in vicl la 650'C. Contactui
trtsi-Si Schottliy cat'e are in5,l{irnea de 0,85e\r cind siUciutr
este o barierS, cind siiiciul este de tip p.O
este cle secliune intr-un ase-
tip n ;i 0,24eY
ranr.e.an,enatajter'*:n(zai)steolrpeosatetedf.iatriei tilnlizfaigtuqriird,5ir..r6s2elin1i3c-ol.nAdcuecstotatrreandziinst,coarrearienclLlnenlieL

-ir.i.rl. i,;.$2. Trauzistorut ,1L1i # :;ui'sa 5i ch'cna barir:t'c
s-:ru ol;linut jonctiurli p-n (c1e exernplu. CdS) ; (b) se poate corrtlola uDor geo-
met,r:ia can:llnlui d.in"tre s*rsii, qi rlrenti ; (c) eliminarea difr-rziei 1a temperatuii

isn:tala,,il,t(belr'h)(priaedln,,etiluroLnxt.lrieti1aa. lJiIsz=e,aanrlteeeralr{inasputerrsareanitzu,si:iliidtoorelltnis,5einmi).trcistciiemtcielaanrrnaeicnctie,nroicsetcliecaitiareilteltcetrlaemnizearqisirbte'uo.rn1r5tlo,uia:

cu cfr.:cb de cirnp, conven{,iola}

B. Tt'{}.nz'istorul, ctt, eJect tl,e cimyt tle sultrajtrld' cu slrattt'ri s*biiri

in mod r-Lzual se realizei.lzi astfel. Pe un substirat r1e st'icii, sau de
safil so rlcpun in vicl doi electlozi metalici (tlin aur sau aluminiu), eale
cCluodinSrs)ltoiptlueitis,el,feisguculsararaeryIsti.ec6l3rdeeanp.auS,neeseclpueapnil'Last{r'eti lalaatpooiziotulliasnttaosnrtrlda(S,t iesOgea,m1s5ia,cocuunAdliiu2ilcOgtio3mr) eE(aCi cic1nSaenfian"slauau-l
elect-,'oclul porf ii (aluminiu sau anr). Se poate ploced.a si invels cu ordinea
rleprurerilor ;i anume : electt'ochil por!,ii, stlatul izoiator. semiconductoruL,

zois!cr

Subslrcr' T
C
li a) )) u

sru

?i Irig, ir,63. - i.ranzistoii.il cri eft:ct de cirr.rir cu stratuli sribliri
s".s
s 192

t6r 009 'c - tl

€ac no a.t€olTuKruos€ FInIrroJ o op F?€p a+so f€r8q op rnln+uJls tsoIIIr5.tK,'I 'cnrr
-ro+ rnlnrq$qoo il4uq€+s IndIrIr+ uI l€g.olrl uI Jo+qozr ulp rolruor+colo'? orac
-o.r+ op rnlnsocordE+IJo+€p rlltzruor lrrorop opK?€p +ots+uoc goeu11 ;roltiozr ug

:nrlnau-q:crruqo-D:rol.rozr-,"t;:i1il1$";tt-t"lsrrr,"aptzucqcpu*ir.rFu1q'r-9'9'o*rc

'*1p'; (q r---l l

x-'9rl,l'r I it y
l.iItrLtLll-
|-i
p:^

?rrr+rzod gltli,Bds gurcr€s ap aunr5ar o ar€dt- '@ tg'g '3!J) oO q ''6 pula
qrcun1€ olsoFq"a+s os (.{lt?+oi{cs rrorr€q) o.n3colct op InlcB+uo0 'Kztsarn}.Bs
lts+oru urp cruoJ+colooui.ro+ rnlnluoJnc u or{u.rn1,us os
In+uoJnc 3.ro1u1oz1 ap

uI -reoo-3ar+los,srfJac'3Btncorpill€idu,€too.alr€'e(crg8orJr{upourrlyrllenr3eusr"unJercoicsl€+onuEn.sorIdoo+opz'pr'1BouuTolrrol,pr1'ucQsrccuor.ofurJgtosqlu'sSopl upfl'unnz5tu};cque,)t.oqrforJp?l+81ns€"oceIouo1apdzr{o€frpsuoc)JuI.S!u€cOIurqJ€o+Juco?nauplsole'ug6u+oprsp+{rrrcuxpolouiuc€rtoi1Tclcuc.'Tuzctr1rrncznur}),rrlrp}q.uJuoaoso.rrrou,t€l.losa€d[asdur
oJ€c In+cl]+uoc o:lso noJl+sano"uerIinc+npc€u+oucorci 'rnlnJo+tsIozr InIunIo.^' u"r col r,l,u aJuc
olasoaolcl op !+,ulrur{ .ro1ri3loa n.rluod ruoJlcolo op Jo-L.razc,r
un tsc uztouoricr crurqo ln1c€+uoC 'rnln.to?qozr e er{cnpuoc op rrzroq q3
- *?p-ccJ€or.orlolrcJaonlJoJu+rpruotuscilr{uuprrco?qusJlup€orercoirpr{nt?(etc[ I(urn{"lurnoe.rlools+urlepl;lco€c.zlIu,r}ctiBnuTlrrc{.sruu;ocrqrJluo,]aoaoea.ulrcoouc€oo+In€{+te.r.u1arfr1u(urnno1€lns.oaroJZr1.:tI,u;] 1iauopozul.unrl

(slq) ' i tg-"1fq"Gb-reb )u'".,,(-#r) +:',

I\

srsarclxe op p+up also y
orur8.rg1 In"rTc ,l3 oJ€Inurncts ap l€J1s un o,rudr Jolrslozr uI crur.ro? l1ir:tlirqco
;rolqozl ulp ?6rD o;rr*er op Tn.rcul llcop crur rtsru otso i?laur
v.I '@Tg'g 'oqry)
on---ouIlr€.torp?d]Dt3-o'iuu,JJr'irI6+31orl+utlolr1u+aso'.cazrroEa;8ui.r+rroic4eul1areolslCooarqpul'sc-Ienrn'l:lBJ.ugrcF?lcgnrolruIluge7lp.'9luralpl'rp.gcruorecIJrn"o,zr.]nllrcqtu8rocral;eatrlr)rqrn"trcireocullrrIar-lnL{usq;lanonIz.netooo,usi.lorlsd'alctlerolruou:zrzr1lrrlruolIo1nrs?Iinrcog1ulJcn+cot1uu3lte?o1loruCorcooulcrJit,.a,iror'lllorrxl-l,+strcJualoccaoz€tzspr}
rnln.rolulozr oy3 rrncolnsunorJllsurrsoriii{ug"leeu,llccTnop,iridocoapcfaJo.is€}otsopuI.rTo++€t3uloruzrrJ-Io€}toopuro1?rJ,-no j1f,tn+"otrlsu

-Jo+'ulozr-I,t?lar{.r

uiarpn+s Ts illil o lso Il?+otu-.ro:f'uIoa-IB+otlr lB,rn+cn"r+s Brpn+s e? op alurr?rrI

Il?lolu-.rolulozr-Iulolll Jrn?onJls'gI'g

'a;ttsor,ra+ua e1a;r.r5rlud
ul +tsrpr1,ls 'luuor4ua,ruoo pfeye;rclns ap dwrc ap +coJo nc rnlruo+srzu'6-.r1 oIts
olac nc o.t'r3lrurrs l.uIS ounrsua?-q,uaJnc oFcr,lsr.ro+cr3"ru3 '(qgg'ql 'Frtr) r;ruut4doc
IzoJlcalo nc
drurl rf;e1ac€ .ulor+rszrozru+€cro1loerloS.ro+urrencueousndlna.rpo+loscrzluetsg.r+'[9o1J]€ogurJor.rzpvrcS u,ra1d r*'ti1ac,r: u1
FZoJ+coIo
gsrns

din cazul contactului metal-semiconductor (5.7

,:I qtr" 12(Q* - O1)erlt/z
'

unde -lfa este concentra,tizl irnpuritd,lilor clonoare din izola,tor. I-.,a acest
contact proce,sul de condrrclie este limitat de electrod I tensiunea aplicat5,
cade aprrtape in intregime pe stratul de baraj. Menliond,m cd, rrn izolator
intrinsec are o coneentralie neglijabil de mic5, de electroni lncit ar trebui
s5, aibd un volum destul de mare pentru a suplini sarcina spaliald, necesa'r'ii
stabilirii echilibrulrri. Cu alte cuvinte, intr-un asemena caz benzile cle ener-
gie se inclin5 imperceptibil astfel cL contactul se reprezintir, practic c& un
contact neutru. Contactele metal-izolator-metal slnt prezentate in figurur'
5.65. In figura 5.65o (din stinga) straieie rle acurnulare se intrep.Xtrtncl
deoarece I5,r'.qimea izolator-niui d < 2I qi prin urmale benzile cle energie c
alo izolatomlui sint curbate pe toatL l5,rgimea sa. (Deoarece s:u'cinir, este
negativd,, curburabenziloresteconvex5,). De asemenea, sarcina spa{irrlir, stl t
intinde in intlegul izolator. Procesrrl de conduclie esto limitat cle tarcina,
spafiald. In figrira it.6,5 a (partea se reprezintl eazrtl eoniit,,'telot' a:
acest caz r1renpt5,)
ohmice clnd d > 2),. fn cle acumularc de la coltacte
legiunile
ecraneazd, interiorrrl izolatomlrri, und"e nu existd, sarcinf spalialX qi i;enzile
sint plate iar procesul de conducfie este determinat de proprietS,{ile intrin-

seci ile izolat^orului- In figura fi.etr U eontactele sint di biocare.'fn stinga
este reprezentat cazul d < 2L iar in dreapta, cazul d, >2L. Cind. d < 2L
existi, sarcin5, sapalizr,ld, pozitivd, in intreg izolal,orui qi benziie cle energie
sinl, curbate (concave). Cind d >2L, regiunile de sarcind, spalialii. cle Ia
contacte ecta,neazf, interiorul izolatomlui. O observalie trebuie menf ii-rniltd,.
Datoritd, curbi,riibenzilor, in figura 5.65 b (stinga), distanla de la nir-elul
I'ermi la marginea inferioar'5, a benzii de conduclie in izolator este mai :nici,
dinevceirtsXd.ifeinrenfiglaurga((D5u.6-5cXs)inpterecpinretlzeinntafitgeuclaoniti.a6c5teale(snteinugtrae).
situatiLt, este
Cincl r,,.i cloi
electrozi sint d.in acelaqi rnaterial (similari) condilia de btr,nc1i, plati este
rcallzatd,lnintreg izolatonrl (figura din stinga). Cind. cei cloi electrozi sint
din materiale diferite qi au lrrcrurile de ieSire diferite, *qO,,,, (l0*z ltenzile
d,e energie in izolator slnt lnclinate (figura c'[in partea dreaptti). Conrhtc.tia

m

!-4l.Vr:r, Q^z :

c) q

Fig. 5.65. - Contactelc mctal-izolzrtor-metal : a-ohmic; b-- dc blocare; c-ueutre. d

194

96r

'3..v Is q. ollulJap Inlsop Kzv!rv^\ Bsrrl 'grn+€,rodura+ trn?u,rr.it{T op
lo-urilrls1cc cpun 'RrBrlrqJu P.ralJBq opmdop loun+ in+uo.rnc {?c laJoSeo ag

I,u\IuIJre,\rISllErInCxIc-ru'l9s 9e'9Er'lEleICF 'lztt-or' g * rl(o'a)[ : ffi ',t)!'

tS y06 - rV our{cio as rloi; : Qb

ocrdrq alrJolr3a prrrJopr-*-rioJ r*

OD r = 6'il{
ta \tli
(rs's) ,(rvt)o-oT' t

or;rcs eluod as .ruro"rqsFuy ul ry r"& 1a {rj Kur
-l.rtlxo os QD frtsO '(99'g
€I op K+'B.Ins'Rru roJorrBq u orpou teu4{1pq olse OD 'Sry) rur.rag inlrrru
Inlo^1u ta1 lerfuolod ep roralrtrq lJq€lr"1rnrl(nup6o,)yr3yDr7I,u: yTur.rad
ucrurF"rgl o?so rV r*

(eg'c)

'{lzn((A-FQ)D)r-lclxa (1+q)r - (rn(pb)v-)dxaOD}r(rV)t.D-j : ro ,-r )f

(o',Dt ;ilull

(zs's) , Gn(Q|t)zlttLYu)uts _ (t't)f

Q11(Qb)6l5t1Ytt)

xo : J t3I Iouq [n[rraJt;) Inn xJ a"ura.rrn.mlno.r+audruraap+[e6ul7aI ]l(c,eu,rns.1da.r)!cpnl(x[1raa' uarnprqr.K*I+nr.,z]xu'paJopJlnr.snoir]

o,qug uriulo.r pa lrsg8 u-S 'acrsr?lD

(rs'r) I (s ',.,\+

l*p N!$'L
-l-' u"" = (E)d

to-ra.{nnlr3qulor.uo4npul toloucprd.€oea".rrlrtdf?q"qenrsucriauFp.qrao+[uJ6uedo9nr]c'opro,Jepnurosst??eto"sEr+ccsIlxouJooripn+orJ3piolIuo+ogzuJJl1?ou4DzrJ"o6rlpdoutarr")zrrn,Crfpeutl'sr?aucrorrxrrl?oro1ulccollu,J,utJ.niruur?doul1(a.rrru?}lsJ,rr,.,ru)rrU,ilu}g.,er)po]1srn.rJa1lr
Joo'-p"oplroso+ouIu,nuorrJ:lono-u4l'+n1gucua'orlralJlt'c+;lrreco*ao1dlourlsaurlFeao,€..urqrsenctuse.+yer1SroeroppEJeolcr€u8lou+r.+rp€cerJ3u,o?€uoprrIg{-lusqJg1ueoeoql.rrcou(.geor€cclJnl-?sgq-cScosn.lnor(resq'gqsul,q)ra?earrdrnu{'.lgornrlrluuqlecourtls.illadrrs+saureip",o.Bnrlcpaoolxupuern?rraugru3puloiro,'Jait1cS+nsu,.n[rtir-,rl'-iuf:s1Stauuuorl]qr.s18a

:atla-fi+aP * i
T : \E)"J t,ttG-ala T (E)'t

' ,

opun

(os'q) "EP(E)a - @)"flsp:#v?: f
"trtriv
'uts.'l.ttlxa
op ?Ep oilso Jo+tsIo4 un op r:iu.redos rcrlu+aw rzoJ+colo rop oJ+uI eF.rn,t o.ruc

Iaun? cIJ+caIo In+uoJnC '(14>1ue"rg-elood iqcola .pluriuds €urcras op lr:trrurl
Jr.rl"cola lnilua"rnc) rnlnro+r?Iozl Inunlo^ oJ+?c op p+ts+Itu11 r; og.uocl uo (p.truo;r1
-coloorrrro+ olsltuo nus Ioun+ inlcage) IZoJ+coIa ap B+€?rruq rg c1rod Kai,rlrala

cle slab. Ecualia (5.84) se poate scrie in fornia

r:1oo ig, r) - ig,a) : 3 . 1o-? (TLn)z , {5.85)

i(Ir, a) qa

unde I este valialiia plocentuald, a^ curentului in intervalul cle tempera-
turd, 0-fK la tensiurie constantX. in cazul barierei de formi, trapezoidai5,

reprezentati in figura 5.65c (d.reapta) se olrlinc :

pentnr qTl < qO, (fig. 5.67 ct) I": 6 ' 10-? (f .d)' , (5.86)

q(Qr -r- @' -Z)

: tF#{6]'b)qi pentru ev 7eo.z(rig. 5.6? rz G. 10-?4@r f t.*u'i

T

lo.
l*r*,
i[-:-;:-

Fig. 5.6?. * Diagrama energeticti a baricrci nesime-
trico la polarizare inversS: (a)C(qVE@r; (b)qy>O'.

Ia polarizare invers5,. L'apolatizare clirecl.d, se obline

pentru q7({Ot (fig.5.68a) fr : 6 ' 10-? (" . d)' , {5.87)

{(Or*O.-}'-)

:iar pentru qV7tut, rr 6 ' 10-?q@s [#]fu1]' (;.87',)

; Fig. l5a.6p8o. l-ariDziaargJrdaimreactei:ne(ar)ge9tVici<a@bra; r(ibe)rcgi Inrelsim@cr-'
trice

(un exemplu este reprezenta,t tn figura 5.69)-. se observx, cE atit r. cit qi
i" c."s" initial, trec ririntr-un lnaxiir ;i apoi daeresclroecscpceuntcmre$gte.lr'e:a, 1t'rNiuni

oirfi"*t". Mhximul hii J, (polarizare direCtd,) gO,, iar

196

!6t

'(q) a.retu.rog gruroJsu€J? as / -r €cig.slJe+c€r€c .aruc/vuO0n
rgB,r,atJlInn?plsoInrraSJllcs(Bnu)rBc3l-u-elr.er0du11g,1-9i,,1q.6F*1I;d4. u-oIaSlscuaa€s+ordp."ourolpcssosolJpJaacal .ud?rr10ILgn.c+9rgu€samr..rmFagrcJcspuJutrscl€c'o+€t+,uuTrrrdoaz/o1a"aprdura1nr
I+€IcIa{pIulcflu'(rSrud_lu+r)-r{+urar.ornrnoc n.rluad plurze.rit elaqo.rri
kl ep eqelo;rlioa ,g,,ri1e5au

Hao-?p,'€1'g[s1[rfy16gs{J,u.nlirrue.r9IezgoLcr,e.rqa\uu.]ro].uI+;.lrr$sssoonsorrnrqr,sqrluu+zrmznoqcoornca?o'+..nnirr(lc+acsord1no'snqrrp?g3or\lqasac3cJJ(irol.€urSsJlI(r;cunpsrBotnooap)logr-1o;?.(ceflcsr1pnII€:ng€+nausrr.cJscr1€rndu"I-uJuIJrrrrora1ouuoro1u.oprzlgor$+ro1fga.fcacrx,aTcrua€,jo+uorur.lJ-+gogu(s;epEK-?us1ruo+Jcr;ogrcrJapgIIlJFn+uuaola1cu3o+aowpsuiaetporlqs.onrerp€^dcu5coduJJr.acault1Iogi+'szZles,uosCr1lryqeVi.oorrmx;oolfdrr.i_.aor4LcuureuleSlSfsrnr;c.rtouoesrurp{gl4ugcun]gll
arsrrua ep) paruuoq e.rulraxo ap pquaJna o?sa

€"rn+cru+s u1"rd o5enc or€o orr+colo In?
ro11eu1r;rnqla.raduro+
I qWOW I* ganu op-pqef
-uoJnc
.[fl].lgt-6pl-r1Fau a?so Ia ur.rd alrlaun? op uo+e+rriqecioiri
?? IaJ+sts so"rF ap +uarcrJns o+sa ro+relozr Inq€r?s pulC "roi'uiozr ug
eg.eldec Jolalncalour oFi{.u.rqra nus_ruouog l* gzrolenng-o;rtc iruo:r1ca1a a;r1u1orj
-Jarro ap Ininquriqos €ro+€p eluod os g+rrrrJ aunrsuo+ tsI €{tlruouv
al{tz
-uts4 op l!?eru un-J+rrrp +rn+Kci€ o+sa Inpor+cola pulc pFo-I€+oru r{,uy.requr u1

-s-aI+unsoprxu4aorocgl.oIotsdrrreuJpr.rx?ctrsccrxuoo?ln€uuzJon{s+cutsrop{.lr.aartgaz.durqe-o.aduuroF.rsed_nr€r3++lssiortsJ+orlrcrrl€nr Td'uouJaqos zooJrcorulz-'nualosu;unioalsi+1uiog11,nrc.qrlun4[€uIf.rourrt"aurdioiuue"rg\oi,i
oa-'??t?un€+.oroJIlU?u€poocIJJurruIvoo1uJzoonvl€prnlfotrlvtrpura'.a\df?uru1irr€o4slesIuIpJ\nirl1Irt'+.aurrnoofrzudoT€ruo+ct0€Dlageln(op5p.uI)uanl?ouroSuJnc,I??o?n+;orrltolncsuz-tlknaruro+a1oucs1xanqopJorsaquendoEeq+-t,sgr€c.rrpI:rtn1rlr€rylrain-rreutruuong*orrrt.qsiutVo;ut?:oatlf?la,(-Iu1uunr)rIlS+nu: uoI1€1crc;+1rlros-?p.toFsOiJrceJ?{1anrrI:+aBv.r

iti
a

plJerrp ecllslra

9l q- --EtsEaJ-uuJreenalJlJcsoEueJrolrsrl?lee'[ngpc?(lsufcyoralJ.rnr3Jt3rBBrS{-''r6Fus9i,I:'aqF'rf\luBIr'J.luISudJr!(E.r1fl

-l]/ rJn+cnJ.ls u; lnur{qo nE-s sns rtsur op oloc K{trJrFroD sJ,Bc oi€}uau4;rodxa
zr -Its+om .rorar

ur.r6 'a6D
:o+€+Inzo aJ€b_qne.roluurord{1p(gqs;rrsog,rsuro1o,r.:orudnalrslor cJoT?)tEirnrsnxi'itnuuurarxuauuur

-osu urp
E'.ro :I%I0
'aJEurJn

iBre(fvige.rs5ib.7il0lbn)t.rP-oroccaersauctledriestifcodr,msaimreetpriocda,tecuavreeazislotecnti5n, negati'rd,' t1c tip

aer sau ln vid.
In regiunea prenegativd,, caracteristica I-V are inilial o comportare ohmicd
de o comportare t, -curVe"n(fnul)ei1e)c.trAicceeastsetdlimdiintaut rmdeds,aorbcisnearvsap!a,ileialnf,e,
urmatS, conchrzia cd, in oxid
rluce ia
l[a4t5o,4r 8c]a.uLzaeaozda'noumreitidli,stternibsuiulniee,acrceiqmtepreualusi aercleincitiriscp, aclriaelqeteinrejeactiantteenlsnitSiz,ofi-i
acesi.uia pe o regiune mai ingusti, a izolatomlui pini, atinge valoarea criticS,

de iniliere qi menlinere a ionizH,rii in avalanryS care d.eterminS, aparilia
rezi-ctenlei negative. Prin urmare, o explica.tie a apariliei rezistenlei nega-
tive ar fi existenla curentului electric limitat de sarcina spaliald, qi str5,-
pungerea prin ionizare in avalanqS,. O explicalie alternativ5, ar fi legati, de
Aplo-BsiibzOil5Bp-Arelzpeonatatetd,slin, pfirgeuzrinate5.7dL"is1c4o5nft,inuunitdde,fistirnatucal rdeesoXxiedx. idstine
structura
sistemul
punli de Al ori Bi separate de electrodul cle Al de dedesubt printr-un strat
(nedorit) de AlrO". Poate s5, existe, de asemenear un graclient al nestoi-
chiornetriei oxidului de bismut. La tensiuni mici curentul curge prin aceste
punli ;i tuneleaz5, prin oxidul de atruminiu care este srrficient d,e sublire. Cu

cre;t'erea tensiunii punliie se inci,zesc ,si prin structur5 trece un ctu'ent mare
de ernisie termoeleclronicH,. Acest proces termic produce rezisten!5, negativd'
ln unele cazari, cind se observd, rezisten!5, negativX, multiplX' qi este inso-
lit in mod uzual de un efect de histerezis.

5.14. Efeetul tunel in strueturi metal-oxid-semieonduetor

oea aSmemeitcaolenlcolur.ctAoamrebleeleSnmTaetegriiaGleeTaeu[4c9o]mapuozoilcieonndeusctolieichaipormopeitaritcS5,,dqei
datoritS, concentraliei mari d.e vacanle de Sn sau de Ge sint semiconduc-
toare de tip p cu concentralia golurilor cle ordinul 8 . 1020 cm- 3 qi, respectiv,
2 .1020 cmtu. Structurile tunel s-au realizat prin e\raporarea SnTe sau
GeTte pe o fiqie de AI d.epusX in prealabil pe un suport cle cuar! sau safir uqi
loaeiaslxetiedoaaxrcteie|dd,s.,autTotlHuori,asdctteearurmaaclctauuttmeerirri,inisailtluaeiclaec4art2dlerKi-neVsasitcneept*speptoenrestsrzibuterinulStscan5t,tTuefiereiilnsaaimnf4igto,u2plfro.;a7lCi7c5ar.irsq7atic2a3t.leiI0nnr0iesI,tf{iic.gciuuPlerreaoxJpc5-re.i7?ep3--
t5,!i1e calitative ale caracteristicii f 7 pot fi explicate folosincl d.iagramele
energetice din figur:l 5.7 4 l+91. Ca q-i in diodei tunel,[39] cu creqterea
tensilnii aplicate creqte curentul cazul
tunel pind, cind nivelul tr'ermi al meta-
lului ajungb in dreptul marimului benzii d"e valen.ti, din semiconductor
(fig. 5.74 6;. Cu cregterea mai departe a tensiunii aplicate, curentul tunel

scacle deqi nurnd,rul de stilri litrere disponibile in semicogduct_or pen!1t
tnnelare nu se modificS, (fig. 5.7 4 c). Explicalia este c5, in5,llimea barierei cle
tunelare creqte de la -8, Ia E* aqa cum se observS, in figuri, ceea co duce la
micqorarea probabititi,lii c1e tunelare (9' - e-^,,), - Zd,[Zmn1n, ultle. d
este' grosime-a qi d-Eeersetez-isinte5n,I!l5im, enaegbaatirvi5e,r.eiD. eAslatfetel,naspiuanreeapelacaeraarcetenriivsteiclual
porliunei-r,
I-V'
Ferrni-din rnetal vine ln dreirtul marginii inferioare a benzii cle_conduc!-ie
d"in semicontluctor, se deschihe o noud, cale d"e tunelare d.in motal in trand-a
de conduclie a semiconductorului qi curentul creqte d.!n_ n_ou cq cr_eqter^ea
tensiunii allicate. S-a considerat c5, factorul exponenlial.clepinde de dife-
renla de eiergie d,intre nivelul Fermi d"in metal qi marginea inferioard, a

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