Voicu, Dolocan - Fizica jonctiunilor cu semiconductoare

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in regiunea, potenlia,lului inragine qi scade oxponenlial ln barierX" Nuafost
inc.i elabora,td pin5, acurn o teorie corectX a acestui fenornen. Totrrqi, s0
poa,tc estima influen{a asupra efectelor cuantice de dimensirrne prin tia-
tarea perlnrbaliei produsd, varialie
sinnilor strafultri subtiro tclencvimzplluol aelreectaric, ca o efectivd', a tlimon-

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cimp electric pentnr deplasarea nivelelor energetice in raport cu'nivelun

Ferrni se mai pot folosi qi alte metode dintre care citd,rn metoda tensiunilor
rnecaniee qi rnetoda dopi,rii metalului crl un alt metal c&re are rnai mul$i
electroni tle valent[ pe a,tom. Ultina metodd, impliczil deplasarea' ins5,qi a
nivelulrri Ferrni I de exemplrr, in acest scop, in Pb car'€-) are 4 electroni pe
atom se introducr :r,tomi t1e bismut, caJre ii,u 5 electroni de valen!5, pe atorn.

Propriet5,{,ile electrice ale diorlekrr tunel :l,rr fost mi'srrrate prin tehnica
diierenliald, folosind deteclia armonic,elor. S-au m5,surat conductanta

G:'Jlldl/ qi clerivata, a douu,, d2 lldYz, infiinc.tieclctensiune.Circuifun
general de rnS,surX este reprezentat in figura 8.18 [251. Ifn semnal mic pe
fuecvenla de rl00 IIz se aplic[ pe dioda tunel de la un generator, G, de semnal
audio prin intermedir:l unui transformator de adaptare qi a unei impe-
danlc l?r. S-au folosit semnale cu amplitudinea r1e 0,5 mY. Rezistenfele
R^, Rr,, J?n qi -Eu (impedanfa de intrare a amplificatorului selectiv, -4, qi
a voltrnetrului, 1/) se iau mult mai ma,ri decit rezistenla diferenlialfl, -Bu a
structurii. Deoarece circuitul are impedan$X mare, nu se pot misura cu el
diode tunel cu rezisten!5 negativf,. Tensiunea 7 pe dioda de mXsurat se
ia de Lr, o sursi, B prin intermediul rezistenlei -Rr. Yaria{ia acestei tonsiuni
se poate face prin intermediul unui potenliometru aotionat de un m.otor

.*ti"u tt ltaz\,-detimp cu tranzi.stor cir efect de ctmp.lirprimul caz,viteza
motorului rleterminS, rata de varialie a tensiunii de polarizare. O linie de
lungime egal5, cu 25 cm s-a trasat ln 60 s. fensiunea pe rliotl"d, este dotec-
tat5, de citre un amplificator selectiv r1e frecven{'i, care poate m5,sura 2mpli-

tudine:l armonicii a-ntiia, de 1 000 Ilz, qi a funtlamentalei, de 500 Ilz.
Pentnr zr, inlelege principiul metorlei r1e m:isul[ in figura 8.]-8 este reprezen-
tat circuitul echivalent Thevenin de milsurii. tr''.,, cste sulsa variabihi cle
curent continrru care dd, tensirrnea I/ pe diodi, oo este tensiunea gonerato-

rului care d-d pe diod-d, un semnal alternativ ;i ?" este rezistenfa circuitu-
lui echi'ralent care includ.e irnpedanla sursei d.e alirnentare, impedanla
generatorrrlui de semnal qi irnped"anla amplificatorului selectiv. Bela{ia
Ate:nsfi@un) ipi,eTn/t,rudestproulcatruizraarteunce:iirepoiilatiei Taylor in jurul
fi exprimatS, ca o serie
cle polarizare.
corespund.e curenf,ul f
Fentru r.alori (a - V) mici, cutentul prin stmctrrri, este

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a:v*-'LEl9"\r1t;Juu',o-Rin3: ftiado\' Jr"to?-'t-..

unde oo este tensiunea de la generator"ul de senrnal Ds : A sin orl, astfel
ci, ultima rela{ie poate fi dezvoltatd, folosind identitl{,ile trigonometrice.
Rdineezaulatir,maomnipcleihi ridnitniieaa(2fuonr)d*[email protected],tlan|lJei(d(z.)ild-az)$r..lID @r:ld,i), ;i :r,mplitu-

Experimental se mi,soar5, rezistenf,a diferentialir, J?, (sart condue-
tanla diferenliafi, Gu) li derivata a douil, a crrrentului in ra,port c,rr tensi-
unea in funclie de V. fn md,surXtorile cu ajutorul circuituhri din figura,
8.18 in locul lui (dzildoz) sc delclrnini, (dzildaz)lGot. fri [12] se tLilizeazia

o varianti cu performange mai bunc. In figurzl 8.19 este reprezentatii con-
cluctanla tunel a diodei Al-AlzO3-Pb la 4K. Chrrba prezintl, o structurf
oscilatorie proeminent5, ce se supraprrne pe un fond. care creryte gradat"
Polaritatea la electrodul de Pb este pozitivd, in raport cu cea de la elec-
trod.ul de Al, astfel ci in md,surf,,torile tuncl intervin nivelele energetice
situate deasupra nivelului gtrro'esrimmei aindP:b. Oscrilaliile nint centratc in jurul
tensiunii de 0,85\r. Pentrrr L67A a stratului
de Pb, s-a rnflsu-
rat o perioacl5, a oscila{iilor dc 0,12 V. Perioada oscila{iilor variazX daci se
moclificf grosimea stratulqi de Pb, dar centrul spectrului rd,mine in apro-
pierea tcnsiunii de 0,85V. In figura, 8.20 estc rep{ezentati, derivata a doua
in funclic dc tensiune pentru grosimea d:2344 a stratului dc Pb. Apar
franje de interferen!5, centrate in jurul prrnctului rle 0,85V. In figura 8.21
este reprezentatS, dependen{a perioadei acestor oscilalii de grosimea stra-
lghsaimrmtl5uppil5tdie,neoprPPteebbtzi,c,e.unono-t'Cad:\teri,.1csreP,e9rog3ebtess.uree1pra0vu5ont,ceimncm5c/,slpp,Qeevrraa:iofl,aou2darairsiecsveoaforbioaafbiznrXstee"erdcavuinfp1roa/odcdpe, esiiantpltgaalrscadao,.ferricedcveuciauqteoctzcaaaolrcriduiaae-
centrului specf,rului qi o reducere considcrabild, a amplif,udinii oscilaliilor
(fig. 8.22). ln [12] stirt prezentate rezultatele experimentale privitoaie la

efectele cuantice de dimensiune pentru 1\,Ig, Au Si Ag. Vitezele de gmp
detelminate experimental coincid cu c,ele calculai,e teoretic.

8.5. Bfeete euantiee de dimensiu:re itfji""r""i eu mai multe bariere

ln acest paragraf vom studia efectele cuautice rle dimensiuno in
stmcttrri cu douH, barie.re ryi in stmcturi cu trei bariere. Datori&i tuneld,rii
in caracteristica curent-tensi-
rezonants s-a observat rezisten!5, negativtr
une a stnrcturilor cu d.oud, bariere din rnateriale semiconductoare cum &r
bfiaGriearAesc-AulGseamAicson[5d]ucrytioSari-eS) ilOe-,am[26t]r.aAtcaetspteeplraorbgleimnter-(rsrntmvcotrlrurmi cuapddo,urudt,
anterior tll. ln stmcf,urile cu doul bariere din melal qi izolator esto aificil

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lare in funclie dc 1/d, pentm Q:2 Amplitudinea oscilafiilor
plumbului. starea sinne ln si 77K.
a la ?7 K este miritl de 10 ori,

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Ftg. 8.23. -- Caracterlstica J* V E'ig. 8.24. * Diagrama ener-

a unei structuri cu barierd triplS geticri a barierei de poten-
!i:.rl Al-AlrO,-Al,
din Al*AlnO, la 77K.

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.l()istzrlr:.1 ] {nIIt't lrzLr(L Ilr }r:l ,).IllllI(lllt{).).).I i)l) }uii.In,) i.{n) .)[lJ,I.] 1tt1 rri.llt1xt0,) li)ul'L
lt;)Jltirlr(l{>-{)(1 r:p .rutrr,i,),1 x}sni;}lt l{i .r(){rrt(),r'li);r{.r pi11;73.I.1 '!:-l1l).).I llls;t (irt rr
-ri'il.r r.tis;l'rr: rttlttlrrtrrr lotl rrrlttlrlo,trl r^:r.tolu1r) i'r r.r11111.f;.r ur riuurluoJ ltii-
i).il1;) r{r1ii.I}:),)Jil It,) Bi)luIlr{lltt())i},r'},Ill,)s l)rtrrI i).rtlli}utri n.t1tr,lt{ i)tlslJil}i)'E.llt,l
1rrtlttti.1,'llt{.{n,i.).r}ur tunl n;) ;.rrlir.1 atl rr.rrprrr i}f- r{.rnJ,ciB'r,u.lIInt5)"r Ln ,Lr,r.)r,n:(l
rrr,rrl xzrr.rl.)rrrrl .)il,ril1(),r) ',).rIlJll,).)iour;llo;)r'tslr.[ n;] rarx't:]rdO t|lro;Otrr nr,ril
r! ';t,tvl -r['u-r[ 'll.rnJ;]lLr'ls () !)JS:I
ltr,rttltr.rr{ ir-s ttttrti,lrrofo,t.rli)t{ !rlt()l rlrp t}suo;) ,Bru'el8Br(I .').rlr0}onprr{),}{ilr;)>
'1)a's 'r:.[l.i-l] rrr ,!l]1:]t{;)2.),r{i.).i d.is;} ,t:r;rrla;.rau;r '8s

rr;r f gy; (larttr I lri,rols{zrru.r } rrns} [,)r]rrl rr[)(]r.r] a,f{rnurJtt[ti,] uI tu.)r,i,l.cn([

'l,t1t11l l'tt,tol9t 2 uT,t \f,.

"r lltt'f j ;rylrrrnrz.r.I II,I[{orrtr? ItrJool nintq od'cotlrlx;l lod a-s ol'E?rtalu
-uot1xo a{aJ'rl:tlnz.)*r[ ''I.u1?i)rr"r+s r.l.iiuorlug ad g1'uorlrlt €ourrt-stro'+ ttrl] onrrt),rl

('I)Caap_tl if):f.''Sj,tirr!r,,ruiur.tal ci)!.]r,ru-rJ]i)r]Jrraad,murmulrcroulra1rrsn-l{{,Enotrarortqs?dn,cu()i,)rtJsJ;JiJ,tts][qolIta,roJllua'r,la??uil)sait),J4'p. o'r?r(,![

rc?l?iu,{qrlscetgtn:tatcuoalnuctierepnitrarian,c.tioeanrpptlriuelirestiiraetoxJrpilr:oimr qitl1nnertescxaoprcn(i-tnQrzib(i,Vutu{i-a- dVivbe",r)slkeflo) recxoprn(p-oan)e,nteunadlee
viteza acestola iar a - un

Jel Irig. 8.27.-Curetttul dc ctnitor

\ l-J si curentr.rl dc colector in

J dg. trarlzistorul tuncl. Ilste insera-

6I tI (in sting-.a) diagrama dc
benzi dc energic si compo-
vb" ncntele curcutului cleclric in
condifii de polarizarc datc.

vb. vb"t o Vcc

ip0u:nIores:)tlmc, ivenittreeuzx,pacraemsreeiacdlideeeptmeinracrrlieriscudi,se,c?lna, at:iltud{l,'ea culentului electric. Pentm curentul
(cqncentra-fia acceptorilor in-.emitor),

(kTl2nrn)Itz gi a:2dko,lto fiind, vec-
tftoi,cirei.euanlgtr-okr-rl.trurcinllaedrilc,,.liiiumfuoazfigeinnaa:1rgtion,,lu,Ie'rt€itli:oiuDlnl neluafnddg,iengrteuianae:clalereLd.BifPu,ezlkineft,,ruLuonc,udle&'eJng)touoiluedriseloteirncjeeoscete--
melLlcu-cltt;riomnc-ial:oirm,,AaJEr1"e1lkedT1Ee,ecuiiatndnger:ospia-rnlr'ae, ma(,ceottlrn,iicaeDnbntar4zaeitiLia. ^Pdoseenntor'mreilfoecrru;,dlelianntubdalifzucdlze')i,adrieft-liezciDetro"a-l
rti.-ritrn,oil*looleer1a"ir:tirtiueoNncEe,icl"l^r/ains,ri,:tetooartrAeo'.a"z-iCrur.er:olr0tnil,o''sl8ciJideoeiJn\or',i,:,m;a2JipuAcrlOo,aUp$lee.ieirc-nr,tenIiidaoL3sr.mEfGJPuiatjel:S:onl:ec0torxu,;uu5PlAuDesi(oV@ob,slle.3Edgna_i,z]lc=cihiau.fS()cbpeoa-"mn.lzLzicici"deo1fnnnk_odti(,r.5.JauG"cli/atDi&oloer",)u*9Ald*u=se:i
ln* oGan uAs, kn se poate evalua folosind rnodelul a d-oud, benzi lto:(muAD)Ltzl
rxotltreleiribrvrir,rrlin",nii:seadnii,itgtniciinacvads1diiItt[u0n,epcr-AnaourIa,sl0l-eaucq,s0eitit5eVleGorJnmmtal0p,aaAp,eslcestv?enu.raIatClceortJouualae"mlrrccaeJuptil"lmeoooin:annbcpmeilllilJonneicctl,urteci1tls-,iX,da^finncalJtpltetarefsi.iu*lngegeUnnoidesnlrduauexteleilBl8rorte(pm.rrq2-zaouV7uanlsaluztosird"iaeilss,nk,utIctlTeoisLnr.)rDe'riucaapiluErurt5rreegicn,zsancretiltetoninuutnatltalayrtpttJeeeeur6naolovlecxiaoalailJmpnlro,taralaoaoscl-,-e---
ooeficientul d"e amplificare in montajul cu baza comuni, €al cu unitatea.
3?entru a exprirna posil:ilitatea cle funclionare la inaltd, frecvg,nld, consi-
eler6rn trei contribulii rnajore la timpul d.e intirziere a putS,torilor care se
.d:[t.e,al{tbjlmaosleietcoatrzoui,rludSi.eerSylaigereisemterietdocar=tlaacelce*oplercocotdo*ur.stuT"li,mduipnnutdrle,esI,f'"edIzeidss9tteeninltatiirrnzricpeurael de Ia emitor
de incf,rcare
emitorutrui ryi

306

0,r

rPlr)d-!
:''"; :L t1= 0 I
;1-
a
'1'r$oy tr;sa l* inil*ourlialuniap.rroucurucr[o.rr'ula,rndpeureo,crtrltiuisa*sru"1irpl,i0'nron.rtrs"rrr€rJi.o,aI"odpls€aulicgxeospuonp J
a
o-.,r j fI_,
a)
'ail == | orj
J "t
:'o -- (oo n)e
rt
iirg{.r,z1uor rrJorlo{) g,itrgu.idrrr- 'B{ op olalzuur8a.qrecrtunsomp prlirrplrurooJa+coa1iaalu,out1r"i,1Eorr,rrlllunr!p1 "
;l
iir?anpuoc op rruoJ'l.lyala op Tf.IEp glur{'rtls lmrJtss op ra}€}rsuop €),:}sa (r)d opun a

'i.i')C -b--yt - : arP
IIaF

l,;1-['cm)Hirn{p.nrr[crit?ru[ursons)uno{4r!ocp,a.lr'oor+ooralr.i-urllrprc,ocrrnorpnl,rprpppln.lFudtgtionT,rc.rrrB+l?rrtr;]I[suouunu.rrqrzaf?ar))aSsr"lrr,o-r;(rpaoo}p.rj,r-rorru\ooo.zolsr.rerrp-zaoI(nBuSan.,ar+rr:ropl)cJeul4rlorou,ilJE]tcrg,JrIourJcrrS+B,raJr'lBNlnsrBapio]a;ncief;olnii,oolu1rcrdlrg'+auun{osnlEsdl*?rurrutFalloiosol.su.crlar3aanqrtuorrudJrcIerodonals.-/r}zsycxz-,€forruu(,ni)rdr,cup)}rruc14.t.rrL""+o"irrcr(topr'rorl1,l.4l,rraJBuoo"ooulur+].norrt,nxrld}ucspauueurulro#aropJorrriirlr."€rrerS(rup.,9lDnnrri6auian*ta{.snq'a9ir
ard'---'ntg[t!Jrp1rr.o.ar].iu3rnrirr1I'uu.'g.rtutoruiL'oiJusir)sdl{(iso)elr[tutpl.'.iaurrruirp](.rlcn.rane]orri,sstolrrrrdur'.1a''rnru,oc]pe"ri,{'rilr5rfoJ}r'l,rpJrrrl?5noot-{r,lcu;rl,oe\llar]rriuzrurcIrur.erlrlouror.iit}q,p1ltilruql};'otR;n'utcorpls.F..prtBrrcziolocJnlnporro"orJ.l.rrrcolrJicnrl]roJtlrapl+soru,nqgsg1r]ro.lonrain)r-url+cJocrn{sl:muu!aq1err?oailytEa1+u:usy'epJ.uora.aarl;:Jci.rruluor;1p.rr}cnclko*"ltnro.?rossrtinErr)lropa[Fi8rtocborrllJ€rl.rr}s},laarBurJ}upc?lruaeJreirur)unaurJrpl,{tnr!soo.oI]rnuu.-opfqulg+i;irril0crngi}e1nnrgrBrpu.s-rl

o.rJlntrmorr ap lll+'l?.rJn- n{ sria}ur ap ,}uororrlls a}sa ciJ}tclc lnclun;l pur.-)

"r{)Ji}npu$anuos Inrllt rrjule,rrln:.- B{ aunlsJoau{ ap nei- c.rulllrullan dp
[il3*.r]s u{ du{ilsuof,rrrp i}p ooJ?rrcna dlotoolg .g.it

a'liirJ,r rirr*)]{r{ n* '}'B+rii)zJ.irI 1a'*1 IiLroisrzuurr ;i"i:ii:,1*&,'t?r'.i,|t'tttf.f,;
ra{a['--'--l{11'[amriur.lJlr'|a'qiitfrJ.rloitnur{rnoorrin\olSo?1uarttcdc$clorjotouisziluerpcurlao,otiou.t+?lplr.,,i{rg'1rllu,L'uroppl.e,.],rrouorI+tteor}r}1cIrrsrI}d'pEo1iJlstrul;ltsoArfrlr'rzrtlulr'{r-iqtutrr_.orrlrru;€o*lJrerqrJ.ll't?rrisgai']'nuLrr9org{pzonrln,alu1uz1r+.,1Ji'rtruuue-u]poqi.]o,rJoi:r1q,J}c,rulrazucm.all,zrurartpupa,D.aarlr,c.oJl';cr(1oprrgaaof1".1tp-1"ni(stu1r1;rt,or'rlzelpnl.oar6rrudrrutrllrr)ruu1s,rri'lroiluoril:1z]'unaet,ra{rnraicq$r*u1.1operlla&r'1.aoJrll?laroounpuopL1co.odorsuml78,:urcan].?.uqmrlc\an'ror1rD'll.,llrtsrr€r.1SslniairnroJrtolrl:,urrp+spuaI+unruoasnausoxlullnrc+on{ezoreos:tJeJul.rlc(upuzt|ara.lu,nuretr'p1IiTCrolulS(tu;loln"fraaull1p{ruprr"uopsJlrrqrtoa.a,rrbt,,miiur}u1{ei{sr!nuEo.g1garrauiolCJ.lurl,rlonlaasn.Icr"trrcaar1p)z-{,zeI:n;ucaal4dpn;tur.r.1ure"l,oi"nrnri.lauor1q1igrl1/j

Pentrn I calcltla U(lu) trd;uie cunoscute stiritrc electronice. IJe ilse* t)
ptlr'to:limrieiemicr udneosscetltftcoUn(sri)stpeenalnilrtnrcuivaearelecltoarerlcbcuuulaieansrtte:iifrziic1oaelvteaetliien,.ctUsrotnrnaicptueri.lmAdecceaaalcCsutua-l
lnenea C

t ste o t

S€mrc o nd"sct or rnnlare a fost fiicut prcsupuninclu-se o ir
M elal relen1erregnire1ienp{o,.1teenxlipaoleneinnliartl,irt adluel distan!5, a
4 cle acumu- I

1 t'

i lirre. Cei r.1oi ptr,rametri din funclia d"e clis- S
I
tl
I tlibutie consideratii se tletelmini, folosind rl
I ronrlil.ia pentlu cirnpnl electlic la supra-
t
I
I i

falir, ;i conclilia pentru sarcina totalX, Q, T
scrise mai sus. IJn calcrtl cle selfconsistenld, I,
ca[sfoesrterfgitito,upt ainlab[o3li9c]erlrrqeistuoplounsiinnccll benzile I
F aproxi-
\
F rnatia rnasei efectivt'^pentru determinlrea
I.
stii,rilol electronice. In [37] s-tr, presupus
Uixj cii, errcrgia lroten{,ialii I'ariiizir, clupfi, legelr, (

:U(r) q6"iroe-"1"0' tl

irig. 8.28" -- I)irgrarnr ric be nzi dtr unrlt c este tlistarlla ntXsura,td, cle la stl- 1
cncrgio a strlrcturii rnetal-oxid-serni- p-rriztrefaazlihr aqrilirno6iurnneapzctrleampeetrnuetcraarlieecaaraccitme--
pului. Energia electronului asociat5, cll I
conducto-r cu rtprezentartra nivelullti ionrponenta r r-r, mi;ci,rii sale este cuanti-
ficatl dac5, este intleplinitii condilia (para- (
rl c energie tri,., tliscrct, in stlatul de i
acLrmnlarc rrl scmicotrtlttciorrrlrri de graful 8.1)
1
t;D ,t tlsgcnerat' (8ntqZf;6;1Uzf h >- 2,4.
l
!-nnc!ia rle unrlii,, sg|ul;ii-r rr ecrta,{iei Schrodinger, _este explimat[
printr-c fuirc!,ie Bessel .,si ettergi:r slii,t'ii cuarttificate este
clatd, de

Ei: hzr2lSm'rit

"r;rn:de(8rrnsqefliErl,e)utczrfmfi.inErtitletylignliilcocnlectltilloi:lnpilleuni trinntlf'u-oncs{litabbl3aensdsei le, sJt"e(yr)l-a:.t0i sl
de

expresia

li =-- E, -i- trJr,

unde .&'r *stc energia, mi;c[rii perpentliculare pe normalzr la suprafa!|,. tn

stratul de acuntulaie se presupune ci, adincirnea de perletrafie ro este egalii

lu lungiluea, de ccralta,rt l)ebye clin semiconductr:r, adici't,

'," _-- {lt;Tl4rq21t\1!!, lf > Ir,

11l'16rqzp)rt', li>1;T,

aou11nb'r:df.i.tne"e4ip.3ccuimusaLenuYtteciflgoiucuiracrotec6inle:atrrtaei6lf;ir4vaa.pplo6ua,crrrteuei,atzocu2rglitin'aocltr0ed?dnYietnriacscmlaioar,nccvignlauillliioiaunatrtr'rlieelrgjoclmroipnatasi.-rid.i-1serulriasnt*p[s,6eeri8nnnclritlc:irtocrutlsrti3a.

308

6{}8

(etl'g) :";ri -+- rJ 3-10

e.rud,peceiplJee!c1,gc,l1!'l7ltlrri+ruun'tzrsnut;Oii]tl€nel;roElol{u,r3-t4z,r{Llzoti €rJiurJc1op alzotl aE EJrrJ
ui{t'rt'rilu-Il3E op or4cunt uI
a'g/F€/{IaoIpr
ir{lJnc uI K"rri?r?upc] o tsD arurlu riuuoc{ rour$"ruur-ppurqqns 1}o+o +socy
llenJi nrsog.urorg*':e1Jtcc1syo1p1uo,un+';ur1cF{el{?oiu,tuarI}nooSDadl}ercnuzruoocq,1'ebauprufig.rcuu,r1 ap *r{aun} nl ,4tll/}

EI ale?rnuquoosrp nr)
!)ricunJ o o+sa iid Tl'guol-qua{ilrprq tr5.roua ap rpu,E{{ n"r,luor{ sc J€o1}G

'{,1 -*,t} , * ;l

-u,tl+srp,ur5.rllro'itl fpneqqrn- lnpr'rd'r;rIirlpl1ui1'".'jap'nr$r.ir)J}uuyi sinu[i,l]p-!iirlJoppl"c4ul-orr$n.,r"or dgo:]t;;dtX
'lco.rlp o+s{} Flrmlqqt]s rrr]] Joimo.r1ri]Ii] lj]{tJo?cp .ll}lTp t:{uulcnpuoc '(lr?
-am q?I snlri Jnnrnas no) _1 ounrsil.!f $ Iorllu.,u.rn?on,r1s oti ycride os p{ll3';}rs
q-J,trootuumr o{tp.rlIunoiti,rrr1(}sr)u1n;,lurcI frnlrrol,io]o[]ctrlnolnl.iii{l}TJcpn.pr utio,},r,&rurarqsle()f(fnII,)r r.:ltr$a t;ioidaoct.rlr
ejuyardn"' n.rluad
uI '6(}]s--IS
mlnlnclsc Ii1?,ullrrzi),r ?u:]1,1i)rcJriir"r Oli-o (i6's E.m5r3 lcria.rnirl Frluol$s n.rl.
-uad alnurlrlo lso; nrr allrJrrorrlr.r.:rrlxtl i)],r?lprzJ,i ri -
a1notrui)

- -,1''!,,),i. 1,.{ {)'),,2 | (-tr rrtr-.\ '1;[l)t

lrll't;l1.cur11 - i.r)i?.rti i uiluuqrln.sl.r.iirttrt,1rortlll,lri{t1).,1rs};,iJifl't.i]r:lrlr,irr.tl.rolr.)rl':tJmstrI)ri:lso,r}.s)itJ:,1rrut,l;lltpilui;n

3i {.r}'+ i'ff lj - ( "1' - Pr')L -.. r.r')d

BirLIOI op l'|tjlll it-s llr)>-str),1 rltiutrr;t
cIurinpIllp1uleilulr.rrulre.Jrud,ruucrsorsIoiu'l)Jlr)lsrrrl''rur;rd\rrrJ.l0r.rrii1J{r]}rnRs[pu-].ua0mpoIdotrnooJeppirtsozlnalicxluTlolrcrlJsaroarru.;l\f)."irIoiai])s.,ipt'tun?l,n'o)dBJp'.lrri?+lltlls]pl+t,ua'rntn,s.rr-,i+,liirislrJarrrrrilrlrJJll(iIl]lTIpil]!{..rIJrin-l]l]']r(';ur1lrtJ4tl)irsuti;loo;l'rqcuIuirilclrL].i,Iri50a:.,srrl.)rr
ll'iJllu+otJ1scJc:nlsrpcuuuo1nc,lnl.trrrtrl.,r)r,sor-oJI);lr)rrirl(pi)ruorrr1cu,ruiilK3r..)?rsaJ-1pilnrtrrl olrrlyl'tu4i.ilrrrIiorJ+]i]ils1lte,irrpouto1llipl.lr)l.Jl:I'1.lr1iirti:tlru.i)lItsSlsJo.t)!.-u8\lI.or{al.urdt;?rpril''lptal,pajrl}rszit,"iurrJlriq}-

-r-tll 11€ I.l0l.tlllIlIi{}i}l{rti})- IJlnIri IE{tl I.l,} Ir'J}1.iJ,I!;tul al)a}Al} lIi+Uot IInxO II}OJ
pcrlau;rd {rT '{rI i! rrg nr rBur at(l lr;l a.rirro}purrrilJsll }.illsi.rJi}JritJ'Iti.} ',xol.}nl}

-IIfJ,lIular--pl\lr-lL; lilli{ lI.Illl')n.I1S lr plxo-,t0},ltlpII(}JrIurs !l}llIJ'a?UI tll .'}Jll11llll
-u-snrotp,oEpT;]iplqr'uCluoJ,IriUJs.llJ'm]lrJnrrnlurJJirlrrJitril.riiuau,rdqruorlolrIJrDlilaoJSnpl,l'rau,Jgri,uqradl,lr-[apiSlrr.ip]o+-sllq;sr(llr(rl'(..ully1i-.-r'IroilpcBl-lsn,anz.tfn.';rrrir,ersopyJ!ul)nnl-p.pIur,-onyDl{:il);.]-u;tl:ii)]{,sI{
,l[.r.rn]or1J]s ur.rllrr.l)n]s lsor mr ag,r1.1 1i syrrl., rft1 op ali+.r?o]lrnpuotluros r.tr
cJ,EInurnJB Ji) lnlll,rls u1 arS"raua ap ,Tololo,\ru earucllrlrttlni-) 'it.{-6oa,L-d& 1,1u}
-:)nrls ln 'l,rllrrllr] ls ls()r rr rJ th1 op rnlrl.mlal. t1e;ll,rdrt.'xT aJETnuIn;)R calpe?In€ilcplJr.iJ:r
u1 oi5.raua Jp ,rolJl!1.\ru 'rJo,rutryJrlen;J 'il1nur{c1o rrlt,irtorruJ?dxo
rF:.0,'i-u4uerpc;1ruo1e;0urIto:;,;lri rrll.;lr)irri'r|rr;irur',r.\-r.rrrrlr.oirtcllgg?ia6ur:al'+lsst1ougcI'yati;',r1lrtrolrnuaulfmr0lnJo(uolt?.osJfi:l ilISrJn.) JI) rrzus({ v' o.}:tgh -.

=,,,"s1 '(ffe'l lrl) V6tI:'r trii

llr,IlH rrrr-.il1rr llzlius.t {}p

[: fl' i-dnefEigii"ibdi,TrEaerb.al3i,oreOpce(onrn)tncsrtelns]ttnrmnii,lcsirotrua,rera'5le,P1c]lbe,rTolean-,iolJoxr"i{,tn-P-':9b1tt]l2ae'41x,0e2K-1g-p!8iiuemEe-.s3=t.e{?lrl'me5pkprGtel-}-

Lenta,t

tr'roba

E2 (300 K )

E2i2K)

E7 (3A0K )

Et (2K )

o Iriii. 8.2S. * Stratul dc ir:-r-crsie
l!
Iirrgir supr:rfal.a scnlicondui:torrrlui
t
ale rip p.
-n)

-^a

K, .t\

magnetic cle 2,5kG se aplici, pentnl a distmge-s^upraconductibilitatr*l F[-v
UI:lle4l,c2ZourXel'slVfpi;lin.i ccSlottlr.leensscpctuurnerrqitlretenlipilvrecoloeenrlnodilrueccnutataenurlteiincieldjlPuaigibcniulTl-idrler,aee.g:laPla8o,e.lc7ai_aun38Pr0tmtarnlue1uYdinmlpe,at,arl_:p/eianosoc:-tut1el'sae6nt5,rePllnia5alecml:Y1sau\s-14pcs,2,rtmaorl2taf-bea",t{.lu,V-iSiln-,r.
u-Ersm=a' rfq$plngYgr,oaEpsa:de6rpnoeieYn.liPaylina
. ooh
i -Pooco--^^oof,f+ stratului dc acumularr: de la Euprn'-
{, tala PbTe de titi 1, apar lrei nivele
rt I o? ouantice disoretc. Men{,ioni,m a-ril,
j
32 I .j structurile de pe curbe pent,r'tl
v\5 14 i Y I < 20mY se qi.atoreazfi, contri-
N\tal> trutiei fononilor din Pb tsi rlin PbTe"
'o -&-Ttl! rnagneticr
ln'prezen{a unui cimp
12

t0 cuantificator, caracteristicile tuneX
au o cornporia.re oscilatorie.
ln fi-

g0 120 gura 8.31 este repreaentat:"t carac-

4mv t,eristica &2lldvz in funclie cle Tz

pentm structula InAs-oxicl-Pb si-
tuatd, intr-un cimtrr magnetic per:-
pendicular cle 35kG. Stratul de
acunrulare din InAs err n 5r5
:I-'ig. 8.:l("1.*d,I/dV si d2fidVs in funcfie de Vin

structul'a PbTc-oxid-Pb la 4'2 I{'

310

rfe

r-f (H)*E * (H),"ffJ -;tc; : (g)itu ' 9t
HilLI
ap
rr{u1e.r op K+tnr}op uo.r+oloio fr}+co}o €suru -.ra
-{s
'b(L - t)l(n)s -'A : A rtr a
-,]u
T1lu€qi{rxs urp o(u.,rt'cnlut pouJe€c.Jt?IIn'l1o.te$eupnurlszuuanldasuar;{oqco (r1 ep oricung u"r) g'iu"e1cnp
-Troo uI InJ.rIA es ntenco lo.r1 .II
alourix{n qC,
Iau
To(-runpraI'sdtr)?rrlp*F.o(rttrDsrfoionUpt uvirtuLaor+ppuuroaBdd+'eE('pAfJtnfsot-E-roru,u'luYnt,dt"n)bn(esc*pot.uurtu\llogrol]rllmlu,b]oI')nEd:I:oo(^U(sIAu))ko"zq9gu?arFes.icl)o.rutlacoJ?qauXoutsl.Foortrtdts(sgctr)z,"o'iillrJtr{"t.l1PalSpnitl!'olxfnf|l
arl.al
'(tr)'a-(,1)'g-+ri :,It
'aJ
/ /plqfpe''un,1ur{petu1lqolds?rcl+tsJiJ)oaslr.o+nttprsas.t{saI+u.rceaeclJaeg.1rcuracla1l€F1tc.lruauirouarEupsrnua+orD+{ncJou+nllsiy ;rud'u ,1tr}/"Fp rrl itrLrr}JJIA -F]r
rJoIE,t e.rtla epl{eFcso 'niutlzo.lt{
l1.rln
rnlclolloJ o1rcr+srJo+ct3;n;,1 '(aloti
jp.
-riplC,rcpiuc4rc_lospaporlaiuaerlueo.rucosJrppezleoeal1riuSauuI as gar:p) g giauny '1,rnglga op orr,]s o-r+t]]
oyzuoq gJlJr?runc gi.eyu.rdns -u.r
ar{ mlncrp
tr I
':t-uad.rscl crleu5ern du4a u11 'Jolruor+colo E troJ+olclc ?Al1coJo ?Jrrf/dp o.e
-"rIJ
rzuaqqns urp n€puET Jolalorlu o+E.roJt?p roprriepaso Impn+s Hz'Br.lEA
tsr^tsltT r{1 puI} tAa
;ltrillsuol
ulo utlq
or'ncstrrrpn.r?uu€lcd+tdu'oo+rltus?IlsJJuao'taIcrlIl'otn;sulorranprlllrnrelouolrstioruadatllaoncdac;;lrxoalKlrrrrpi{.urt:z'FBircaqssqo6nys?zu'tp;lo1pJuoln+uuE.prpdunrotsssTr(erluoit^?aurpur Jopzrrod[
'ui"J
-'pqcnisruoutroeunets{upouwtsTaJpopqlrat;aorru.reXtZl €na.cro?a'EapyrofstycAsugl0'{8uIn;l,o1rt n"rluocl cIIqEAJosq{l -n?€
i.(
urp ar{onpuo} i}P,
{id
ltw ij
iilir
00r 002 00t 0 00t- 002- 00t*
JISJ
7Z1A4.PriJlr)lllrsrtrli.r):lrur'rltllrllt.uj':pfllJ-Jltr'IlrIll r,1)rl ld.t.,(:
n"tn-r)l{!
\i 6'1" :rr
rl(I-prxo -uslv?u,l,utpJ/r/l?lJpll-ii'sIil']ul'l"'rIN...rn'p -erd
,rtiarrnj

qd-Plxo*sV uI

;I0IIJF+S alu IlEpuuT JoiJlar\lu'l?z'Ba;I{}i'up rls 1urggl )Bq,J.1nan"lrrqfua'fdiaaulrrri!tfrilr:a'*rgl,
'rrlepcso at8pTrr:.ro!5.a1le1a?iIJ+rt+snfJrJrsas+co{r{i)}srops g;rn5q urp
criluErlD loirlr tITl o.rts 8_uIlrT0T "
JRr rlalu

se poa,te rletermina nr.Isruinrl tlifrrlcnla de tr.t:trsiune tlintre eloreri virfuri SI
suece-sive :rle condueta,nfei, fohrsintl r:ela,lia
i'
:rttl,(H) -(,I!'--a- 4. lv*{H) - }r,.,(J?) l-t
('
;)c :1

Pentru r,leterrnina,re"l ]ui i se folosesc oscil;r{iile de perioa,tnfi, mzlr<:. tl
trl:rliera pentru un electron II
,S.28) este rlatri de situ:rt, l* nirielul !'errni in semiconductot' {fig.
ir
,p(7) : Z - iUn(V) * :r)'

upLUue'eocrcilote-anr,"cp/Z,l-ari;,reisuctplaeararoelrf.lirnnPli'oateadlnotuetrlraiaurfeel.r[l-ee:{rc,,:ltumroeianoggricrnslteoaleta,one,ola,ssucucnepilardnalirtri:alitenelairri,mnnsinicpnirro,ntdiuerzrnnol!ln,dsidaVeuituzcdltoiednreuoftsursueunipi.clarDlaileeifiaoldd,ilaee-
F are loc al,unci eind niveiul l"a:rrlau din subbandri coincide clr nivelui
Fermi, acliei,
p -i E(I/) : E"(B.)'
18.4?)

-Din etu*!,iiltl ($.40) * (8.42) se obline eti :rtlincitura in rnzX lrlV2,

a,6unei ciml niyelul }:andarr, ir,, inl,ersurteaz5, nivelutr Ferrni apare Ia, ten-

siunc.:l

V"tH): L', * -LE"(H) rttr',ll'tg.

C*Utrrbve)dedeV "un:deJ(sHe) couvers^ toate pentru -H -> 0 in punctul Ti"(O) : sFll;a(1tu--

poate determina 1. Ca,pacita,l,ea,de suprafa,f'[, C, a
Iui de acumulare, elatd de

c":dQldau:13rgqd6q"

m[soari rata cle r.ilriafie a lui Uo in la,port su 8". In pl'actici, in struel,ura
rnetal-oxid-semiconductor, C" este in sel'ic cu ca,pacitatea stratului ele oxicl
;i ceea, ce se m6soar6, este rezultanta, lor. Pentrt a face mrisurd,tori corsctt;

ale lui Cu, Co trebuie sf,, fie cornparabilii cu oa ca, url,r'imc usi trebuie sa flo
cu:roscuti. Ijrimn cerin{i, necesiii, un strat r1e oxid gros de citeva sule de A.
Nltrsurarea lui C ;i d0ldv'itr func{,ie Adceeal'.,srytriidme eIyt,'ostel5faccoensptrfininmrentsoddua-,
standzrl'd a rnoduliirii
tensiunii electrice.
larea t,ensiunii 1re oapacitor rii de-
lectzr,rea curent,,ului ca,re curge prin
C lprobd ) r:i c.u ajutorul unui cleteetor sensi-

cdtre bil i:r, faz[. Circuit'ul folosit in acesb
d'efecf or scop este reprezentat in figura 8.32.

L-apacitatea totalS, a sistemului este

d0 l r,!
''' dl-' c c,t' oo '

unde

I-'ie. 8.1J2" *- lirprezentarea schematicii a cir- -c ,, -il9-
dDn
crituluj de b:rzii pentru rnisurarea C gi dcidV'

3t2

f 'i (r r

uutror(L;-.-:rT1:lrrt:i\!ito1()rtlr.ruul:r.Jr{II'1ilrlSr.trsrzgJrJtS;rn'j-r5*((-.rrirB}fL..drg-J;ir;{l'aflr).u!}giiu],})a::l.'tr1,!-+r.'l}JJSrl*j.)Viann'lltptq3n.it}rlu1l,1illit}r]s.l1Ii'sunllnlaiJ;lrli.0,trl.rrurlt3s.lor.tllr'lltros*l.lr,lurJlIu\I.lrr:n'tu+uB)|rU{Iror1r)tJlLuJ},pcltrr}t{itu-.-;[nlr1iuozr}t-,!tln.l{Ill].li)1l,t}tllloE1EF{rtEuTtul.:tl[rlrIl]li,lll.Ju:rl:lJnir)\llu.-rzI,ctr\rjl.(lJll]1ttV'.id;.ztrt(]rxlillur.lult;ll.t'ilr0r)ulsf)lt.tEIirl'I{[l[]l}ip'ol,]ylge,I,.ll)illol,i^littris.trlr.rn.rirr.ll.tl1..l).tlllrrJli;]ttlrI],1Jl-ioud,6I]);'^ni].g1J'rt!](rJ1t'slp;ttIo"1:l;Ii)1rp1lttr;ilIl.].lU"l'.);IIlpt*)n.'.tr,.llltil,ll{]rsrilrI.!ll'I}ttxrlll;.slJli3otl}t]J0{;liItu)inliI}loJ5lIliln.}Jrl1qIlnl'{ltaull.llarl'r.)s''ar)Ill1a?ttt'rlill;J;crls)u)li.op(tr'rlllxtirsrl7lltlljtII,ft'Jl:Jrx,tytl:t1.lt'rif.lrg|x,l\il'']iJi:(i)ijortlllrO.I-tupt;tl'llP-tJ;sI)liotr;)ctill-lljsl\\ital.t):r{(u-i,l.}i}]rlIl ;)
,)
1(|l Z g-,3ro alrrjrpuOJ uI .ltlli)t:;J ls()I llll .)[Ll{}]ll.Il'lrlllll sVU}-prYg-(l{l 1-1.r!r'.l.c11,rlr
l
;r. I " "Jtr r! ,; rrtl 1] J,rB{}'}Iznn(l}'a,i(}.} ri.l.r.iFa.}lli rtr.ttl r^r1rrrl1r[!]]]tll lJ ,]J1l(iiri .),ll;;]

;{'Y;r'r1} I } 'i";Y''nr;

{aririlrr-r.,1 uriulor L'ttr:,-r!(i[}rIiu}uut,lrr(lliy) ru].i]usutj.)ii}trlrl},Irtl(.}iilf--r}";}lIitii:l!;ir}Jr.llittilruftitolr.}t.)uttt.i1l1rltltt1t"rrlI"rl1rl.rfLarttl

tlJr-Trt}J1l

pitrul,rltlrtttt.).),Itl ]ll']utli rl1't;liJtt.1r rttrl'!l'l"i)qill.trl(tlt;r)rtltIitt{n!}'oslru,tI(I}j}iiI,rtnt:siuFLrgri'.,Il(ol:'}1;-,l)zI;I}l.x1Jilil;l}}rltrrpr}s.-rrl)l1tt\t(lri
-lftl,)r{r lllrl};lll,I!s Itl Jll3f '-lpiJl!.rrl qlnplt'}tulu;trorFglu'iui}.,lLriitlliti]ll}Jo,rllltrl.nlil}x]l]ll.lllirrIr]]li,iii!r:u'uill:t!
rallol] u;ltL
a,+sr Jurlr.li..r](-]!1ar;r)]R,]cltH'u.;)rrullorrlrlr{,lrt.l atl "g u1ttr.r1stz;,t
'rlzt.[
-utrls i]l) 1iu,l ,.} 'lt}ln.1o"illritl,r.r
il(l .rrlEtr.I.)llu ,.(l(j n,) ]ltzt]liil-] "6,irt rllt:1u;l1tt1rpiltl] u+ti.]-!iloJT
rn.rrj lr){}"rtp 1l,I}r{}-sl-lru .ls
ntlnl,utnlra-- r;rilr.r1;1r
rriuultatlrilr rt; .lrie,rudilloi) rrr ri1te1 t:['r;.d;'rtt ,f,Iu(]ltr-\ '].tll ' '.? l]l.io]sIZ'.''llr

'l(')7, ills () i|.l (. r _ll, : /lt
;-!ll
- /r')'{}t' I(')l" t'l /il, I

t

ir.IJll{.'l'1t.1 il.l1. :}t.I };l,li.r ltr llli:l,ixl! l

t.!(,,,i!.ili . ' ;-;i'll ;' /'.i,rlr:i ' .llt "'.llr, .\t,
(,lll
tt;.it |

,1 i-!.i) Jrill;)txIr:.r.rt[ f|]rii]t1]r'tlllt!],]]i;\- " i,n; tlitt.r.\.r'i.l.ii ,).rrli
-nli()ru nll llllllllllirri,ls ll.irrrillilyrlirtll_l I! flttE:l-rlr{}.} r"rrilli:1.i,)} Jls;ir)_-l i)i)rlii

:)i,(.1 .it,lt.il:tit:.t .r,l illl: rilli rl
I1 iull,tsr,r itlllltJ.l'ii.rt r ':i,.\ ] ::

I---.11) * r1_ll

7-t' i')lr

$lF' :J i

.l I) h ) "i] ;J
'l tl Ir I

Lrlx i:rzf,.l :)!

cu Ir, crlre este rliferenla de energie intre doud, nivelc tr-a,ndau vecine a,Ie
subbenzii. I)eoarece variatia Q a sarcinii de ecrana,r'e este datd, rtre

LQ: ( c(y),tt,
J

se poate consiclera LV ca o mfsuril a ira'ntei lui -Di in func{ie de @ pentl'tl
o subba'ndr-i.

c

0,6 0 0,r,0 0 -0,40 -0,80

V,V

Fig. 8.33. - Caractcr;stica C- Iu a structurii InAs-oxiti-l)lt.

H=50kG

!
()
E H =30 kG

0, 6 a,4 a,2 a -0,2 -0,4 - 0,6

V,Y

trig. - 8.34. dCydlr in lunctie de l,' pontru strucLttra

InAs-oxid-Pb.

9rt

(alCt) gfl't:?I "-\)ll'sir1,y'runuc;1.rcldV'fi'j''.tjr,'rug'\.'.J
(t(:plttiIt)ii)Ull,(e; g",/i:;'ll"{(fiu"{-"\,rrlci',s5.^iq's,'i1r1'1,1p(rr:tf'tf0trl1)'t.?i1S}[Sr]{'ul)lfll..L'$('js't.I'{o'r.nJ.\rsrrrz:r}-ntltir.rstr.'.r({f}q'E,i1).'r!.9}E1n,ss\.\1.r1,.'.?..'1-[l)"''{.(1II.
1r;61'CRJrlllpr.:lrrld'ss^.r.r(l'uil,)(i .lo'^rirrl
'uoJsn^u!)I'\i'll 'll
'l]:,I's;rs/iry.1 ;t:to.jtttg JolotlpuelutJS 111 '.i;ri.5r1.n1.)5
ilf tCC 'Ot: "t.lri 's.ti1.1 '1dcl1- 'I{u}^:I "l !ns.l. 'l} ';r-,'rlul i-ru\ '\
Ct) (.i.$tit) l0qI ('!({I:S's0-ilr)l(dc1$lt'Si1td).ud(ii1ll,).'pz'la.',sIltr.tJr-.r"no\lin{):'.l:il)':r's}'i''li-sq\),1:u6l6"loio(1Itr'lr{l1

'it?d '(iStjl 'r$u1 'a/.rotr1- 1't )Inlt)lst.r:) .tt)lJltlr.rJlDlf i)JI:r,[ Jp rtuorfD,y lntil).4.i) 'LrBf,(.'ll,{ i
'".u\roll.rlr';.rrlr3.\t'rfrS''lllirl'\lg,:'(q.tlr:'tr(d;s1t0)''rf(0{l(aqreOItl{):ill(0lt((:iC('6,Iti1{(l:rIit0)[i)))')tol6'tltIr"1l(fili{)l:t]i)il:)toe)l'lt:Cc.:(":{6l1l6_stt}}:ileatlI'tty'''('"s{AO[tLIr;It'.mulf9':Il'{iI)lIni'!(ilt.'glg('(".'J'1ti-/\i.e.{J(.lrJ)\.s_t)i(rr\sr'ttfuf1{ri].l"I''ltl\i.tJt{''ra1_.).Is:lJC,u(ll(t'nr,ra'(i's1tl}1\orI0l'l:.lt.l'r's\td)[(.0.{(t)9"rst\(\1Ijcl:lor'pl,l(,stls$il1-'t.i)t1s!l..\O'lni'l6t't\)\soI"'irliJl!tlt:ItI)1uo{ctN))lU[Il1.zp'lrl'yJOIaAt'lu1.J'r'','s.)'uioIegttl>'o,lLlt'.0rtut.1oj.1t1'url:Tli'];lIr.].r.n1.(r}\trri.,Il.ll,I}11l'rJ'a',L'0.aJt/'.J:-11'"\."l''\t$11.1sn(r1.r!'t-5gsu;ill.l'.,rlrll'n,t''nlri\(',rlo'qri!lrJln,|"'ii"}'srr()}'r;Jo-rul}'.1.lloills\l1i)'}':..','lrl1.1\lttlrttits:'sJll;r;).-',uul'.1:f.urJr\i]U\,rr''i,;'ul.l:.illoorl"'Ju;rlJii'.ls,rliusa;li\1i}r(r)'.r..r}'}'sllrir]'.lrr'rit'(l1l,rtu:))r1jr)i,_'?otu^rrlri'!u,olui('lrru'rrsi.]1,(l",'.rr.B:rlro)l.'),trs(\l)lo)r'Jr1)l\'.rI(rrr\ilLlr:rrt'ii(.s'rilr':r.r.t(r1l-1,f.Jt.l,IILi)il\).'''''''''.1.'',l\1:,:'{s\t-tI\tI\1"I(''''.'''''..'j:1l{l,:!ij1r-(:Ziiltif,irzErrl!i-a.1if.ll
'i;161 'p:lr.Jrjurlli'1ll):;l'l'lu.\'2.)71//)it) r)J!Irt)Jal,i'|llnrs(::riyU'rr
'(lti{it) rjse'!}[:'srrrlr..l l)'r\l\orqld'iillilrrl.llr.l'liJtr)rl;trl1l.iyl'l"ly'ur"'ll'.lr]1\1uirsI:{l'l;"lI'['lt
'(!1(tli 1:!l 'EL'(t1) "lo\'lrrl\

'iq) 1os'1ri:^'..irr,l '-i.r11o;1 \-'\''i!':{il) 1il ll.';ltI ".rri1 '( 0s(;l )'.)l(l{9utlr:''a} 0'!I"rr.nrl}ir;j ")'}l ':-
'sir1,1

'( ll6l) IAS '{:{: "il.)'l 'tqj{i1) :0f;a'zI ".l.'.}. "";,1'u'lrrr;ului)riio,r,l.l1li1llr'),t!l\sr'rr1lririls{'{\l'i-'lrl ''(Iili
'(a9(i '6
'.r,ri1 'si11,J '-i.rrr.r1 1 '11 'ft
l.) 6tl{} '6J "s-ii'1(e,1r{'ir}r)'0(ta.;r:9lCrlrtl)':(I;lg'"fliCouli:a1lll'i)gu.11t,lpLu"i.'t\rrri}t"<;tru''Jsl:{rir,r'}l{!tr'{l.''rrnn"^stoi..t.r'.,.,rt'i)\''i1r'..1L'l
'('1(E16ltlj)I)lttli{{i)I't't0I "1?J'I's{q4'1tidy'!}lBs:I "tr'iiur:rl'.1 '-I 'g
"u[uol) rtuls^ pltos'lt] JJ'Jr;ra[)[u{' 'q
'{pl.6l) [l{i!i'ta "}la'I's^-ir1.1 '1dd1:'ns.l.'l] 't}!us1! "tr'iiut;tl'}' I .N
tl:{jl) '':}llI'.r.r1;'s,iri.1 '1.)ssE,\'i)'_\\'.r(}{trIt'l\ '.)(luIB'l 'f 'r!;\rl{rtl' "'ri) 'l:t
Ss'.94 '(Stt;t) f;aq'ILg''-\)lI's,fr1.1's-i11r5'it'.\\'ucLuirc.r.'l 'a
r\\

!rr.'ru:r{)oI'rgIB

CONSTAN'|tr I]IZICE

tr)enuntirt Sinrhnl Valo:lre l)inrcnsiuni

Nunrirul lui -vo 6,o2i9.t023 moleculelmoi

Avogadro li 1,IJSOtrl .1()-23 joule/grad Ii
1,:l{JO.{.tt}*16
Constanta lui I erg/grad K
-,1-,t6,8001289..1100--110e
Boltzrnann ).11 Coulomb
e *1,6018.10-20 U. e. s.
Sarcina clectronului s, 1083 .10-31
9, 1083 .10-:8 u. e. m.
ldasa (de rcpaus) 3,8541 .r0-1:
a clectronului kg
Fermitivitatea .t g
spatiului liber iaradlnr
1,1126.10-rr u,t.s
Permeabilitatea 4;-1l)-7 u. {:. m.
spaJ.iului liber 1,1126.10-21 hcnrylrn

Constanta lui Planck 1 u. c. s.
u.c.l1l.
Frodusul dintre {i, ri252 ' 10-31
lungimea de undd a 6,6252. 10' 2? joule .s
crg.s
fVoittoeznaulului ntriineini einrgievid 1, 2:t98
2, 9979.108 prn.eV
2. gg?9'1010
tn /s
L^lIl ls

31.6

;rt,;

Jri sor.rrltr\{):)r-r[) l\crr aill 'ssorr'11,\p'8 lr?{5{rJ0riqr)i)J t)l (t]rrorlrouaqd lucrii{[{d

o:] oFpdl1\ou]l O{sl?(l osoristil?.r} {J:}. oAtsq {[raL oq/t{\
rsJ's.JuoJa'oea,suluourroasusfuqn.Su)[ru]-li|ln.dralur.{lrra,uJ}tir'))oit'o)il.ll'',a1-lnsJlups}ooIl]rn,(tLrtlcioe'BJJcsrI|{rl?);sl)ndltpupdJuaesi0irputr.tlJi;l)lrltl}rrFlil.lduiapl:sl-isu]i)lJalr,d'rucd{dl{,sl\}o']?i;.]psraJuul{1pl(n}0a)-I6ot..dl}lJni')zru1otll.rcc!})'I-ln.i'lL.tJurl\'5d\}1s.tsrl'u.]I1IIqatl{u€aIoJ'nuoJpbScautqSu'xooI'dlgEo..rJrut1aoqulud;arre?'o*qo.uXodr
l'Jsroiaol.ucrnurqgp.curnao..r?rllr{-plu-J!aI]IIs'uu+IJtorJ{pq'ett{leuJ.oro5.rrorJo1Jogaqltd{lo)u;otB1Acgrilrt1(s1tsl Js(.urr'Ja(olgc}olrt'rqIr-ill!tttto''-u\a.)J:,}t}'Io;JpiSilunipt'ttlll'tBosrr..I)tllottsr1r;orol-rq:sc-olIu'lspalaaSdmoO.JlItt{f)
oq+ Irt;?ai) {1r s}{rcsi)rtl g ;ra1dr:qr"1 'sJas'el Jo}'illpuoJIru;ls }o suorlecqclcle 1,]urr

sar'1.raclo.xl rr11?rrr or{+ o} r'Ja}ar {ooq aq+ ytt ,to1tl'uqa [)u{)Ji]s .}qJ 'sJo+aa?oll,
()+ po+o,\Qp sr ,roldtqo }srIJ aqrr,
pa,n?.rrr{i |rrr 1ra11t{0 ;o dpnxs oll? 'n'.ra:ldt?q? 1q5ra .1o p.lsotlrtroc s{ qoo{l
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CONTENTS

{hapler 1.. ITADIATION DE'IEC'I'OI"S 13
1.1. General considerations 13
15
'1l..l2l., Irigures oI merit 77
Noisc 19

'l .'1. Pcrlolnrence iirnitins 2l

l.J. ]Irlrsurcnrrnts 24
28
1.6. Photoconductors
JJ
1.7, Pltototliodrs 36

1..3" Avalanchc phototliorlcs 39

1.9, Phototransistors

1.10, Thermistors

1.11. Piroclcctric dctectors

Ileferences

(ihapler S. SEIIICONDUCTOIi LASIif'>.S 41

,1 ltrtroduc tiou 41
Stilnulated ernission. Laser effect 42
46
.) 'l Popuiation invcmion itr semiconductors
48
') tL \,Iaterials used irr semiconductor lasets 51
55
2.5. Preplration mcthods
2.6. Ilcterostructure junction lasels u-')
2.7. Delay and internal Q-switching effects in scmiconductor la-
80
sers 82
83
2.8. Osciliation. X{ociulation 85
2.9. Distributed feedback lasels

2.10. Holography
Ilefcrences

Chapler ;]. SURITT\CIi STAT.ES 88

1 hcoretical considerations 88
Sur.{ace statcs distribution 91
Real surfaccs 96
:1.4. !ixperimcntal mcth otls for surlace states sLudying 97
.J, J. Surfacc recombination 103
Ilefetcnces 108

{lhapter :r. }IETAL-SEi'I ICONDUCTOIT CONTACT 109

4.7. \\rork function 109
,1,2. Energy band diagrarn ol tire metal-semiconductor cootact 113
4.3. Schottky diodes 119
4.4. Schottky diode rvith guard ring 725
,!.1t. Experirncntal cteterminalion of the potential barrier height
4.6, Negative elcctron affinity structures l2i
4.7. I'hotocathodes using negative electron affinity
4.8. Secondary emission 130
4.9. Cooled cathodcs 134
4.10. Ohmic contacts 138
142
Ref erences
r43
744

{ihapter 5. h{ETAI--INSULATOR-SE}IICONDUCTOR STRUCTURES 145

5.1. Icleal rr'. o5 structilre 145

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