Rapid `l` - Shodhganga

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Rapid 'l'hcrmnl Annealing Kffccts on Electrical and
Structural Properties of I'tfl'i Schottky <:ontact$
4.1
1.bPdwrka
Indium phosphidt (1nP) lurr pined much amcntian mwntly due b its ipo*
tcchnokkgicrl rppliGuionr in prrtial L v b such as high-spaal a O M . ~ f f k t
& v b 131 urd c i c w w p t b 141. inP ir
aansinas [l-21. high sped
M anractiw
suhsaatc mawrial for thest dcvios hoaugc af irr Luge ekvbaa mbilhy
and hrge salwated drift yclwity o f cknntrr. Mcul-lrmieaducnw (M-S)
form tbc basic building blocks of thc c a m p m i l s c m i d ~ w
mhwio~y.ThE
ptrfbrmimc of M-S L'onwfsdcprnds pr.dominan~lym I)n: choice o f Ihr moul. Ihc
doping densib of thc micanductor and thc quality o f che s c m i d u r l o r surfkc
bcforc thc deposition o f thc -1.
Schrtlry harrier cmtrrts to nfypc In? thu haw
hcm invcstigatcd so fer hvc all jicldcd harrier hcightr in thc range lrf0.33 to 0.55 cV
15-71. Such a low barrier hcigh~gives n x to n v m lukype c m n l s whi&
detrimental to device pcrf~?rmancc.In cwdrr tu Jcwign ~
W L S
with
ur
improve9 ttmnal
and clcctricnl subility, as well as dcsinhlc m ~ i o y i c s it, is lmpurunr
to hve a
thmugh undersmding o f rhc rcacliunc;of thc cuntrrcl melais wlrh InP. A ~ u d of
y ttro
rcactiuns o f mctnVlnP contacts can he useful frrr pmliciing and undcnundinp Ihe
hchaviour ormore complicated ctmtactr, such as r n u l t i c r w n ~contacts
t
to InP uwl
contscts to alloy scmiccmducttm thm contain In and P,lntimrtc mcul evapanlhan an
n-typc InP jiclds p o r barrier height. Man) invcwtya~iimnhove been undar(rken In
MdCr
10
improve
(hc
elwtricnl br*hpvkur o f thc c m ~ (at damn* of the lukyto
c u m t . an incnaw o f banicr height), which stmngly d c p d s MI (hc mkconductw
sorfafe prcpnntion and on Ihc metal.
Scvcwl mctai rhcmcr have hcen u d tn liwm Schortky w n W la n-type InP
in chc pw 18-20]. %m
of them wcn: Lhmnrlly vtrbtrl md I& cffwtr of ~
l
h
g
wcrc studied. nKJc srudie~,hawva, w m [email protected] cenremcd with the M i l i l y af rhc
Sfhonky twrriers and characteriring h r r clacrrisrl pmpcrty ch.ngar dw lo
annealing. Taketorno Selo a rl 191 rcpurad Ihu thc Pth-lnP bhatlky dkwlrr famed
by the elofbochcmical ptvxss p v c highcr SBH valuer (0.86 cV) rhrn W famad
by the conventiml clactron beam dcparr~lianp~acer(0.44 cV). J a g d J(101 hn#td
tlmt the W i [email protected] o f Niln-lnP SihUky dinde wra Q-I
with raduocd m w w
kakage c u m d c r i s i after h i n g r thin Pr Inmkyw betwbcn Ni wd InP lyar.
Chen et J [ I 11 fabricrlrd novcl kigh-acnrhive M n P WW&y d i d hydmgm
~nsonb~ekclmhplmin~rafrniquc.ndrepor(#ldrrrthtclsccmkpap~~
Horwd, et ri IlZ] [email protected]?bMt
k
d i i exhibiu good rrctiWian pad-.
64
y barrier height of 0.83 cV was rchiwcd fix Wn-lap ScRotlky diodc
using Hc1:H.Q w r k c tmmem. H u n g utd Cai 1131 fkbrhcd a high p d a m a m
double metri Schonky w w t m on n-inP using R urd Al. Thcy rqmtad tha! Ihe
ulecbical shanctaistics impmwd dwc tn thc fornulion of rluminumaidc ud tha
h i n o d hnia height was 0.74 eV. Cain and Ayyildu (141 h b h w l A& hl utd
Cu Schonky d i d on InP rurfaxs utd in\wQptbd thr influem of lhe a i ~ p m m
oxide on the el&al
pcriwmancc. R h a b Rcddy cc all1 5 ) sludi lhc i n f l m of
rapid !hcmal a~malingon ekvtrical and a~cntn.1propcrtks of WAu M
y
best M
was fwnd to be
contacts lo n-In? and fhcy rcp#(cd that the m i m u m huricr [email protected]
0.51 cV (I-V) and 0.89 cV (C'-V) far lhc canw a n W a# 300 V. T h y ravrd that
the formation of inlcrmmclllic compuunrfs ar the inrdace map hc thc raucm for rhc
increase of barricr height aAcr annealing a 300 *C. SqIu c~a1 [I61 invcalgatad dK:
effect of annealing on A&p)roninc-RJMt)in-InP Schottky diidc. 'They rqmtod lhrn
the barrier hcight a d ickalit) Ibcttm ~ m0 !60 eV and I MI,0.57 EV and 1.253 alter
annurling at 100 d 250
Y' AJIoh a nl 11 73 studid the ckctrlcrl, stwtuml md
mwphological charactcriaicr of mpidly annulbd Wn-lnP (100)
Schanky sffuctw.
They reported that thc fmatirm trf phmfirms.oxypn campounds ol rhc inWm
may be responsible for the varieticm in b m c r heights wkh annwllinu tcmvtura.
Ccrin a al 1181 prrpareJ Au and CCu-lnP Schottky dirwlcr and rrFparc#l rhrr W
cn'ective banrcs height of Au and Cu Scholtky cnntacts were 0.48 eV, 0.454 aV
0.524 cV. 0453 cV f m I - V nnd C'-V mcwnrmmtr, l l w g
and l l m g 1191
investigated thc clcctricul and smctural pnrpcnics c)f WAWr-lnP .%tky
marl
uul
d m .
rectiI'iion
charactcristicr chsn conventional singlc metalin-lnP Schntly diodes. K6orndy, Nlik
a a1 I201 nudied the c ~ o c lof unmling tmpcnlure on c k t r k * l ud #@WSWIl
w t t i c s o f double metal szntcturc N i N Schottky contwb to n-lnP. They wpwld
Ihar rhc BH d o c d with d i n g trmp#aturc canpurrd to
.r;+m~tbd onit.
They also f i n d lhrrl thc fomrrtim of phoqhirde phucr .( the in&rfbce may k drc
They rcpcmnl that thc dwhlc
crmtPct uructwc pnrvlka krrot
masan fix dmwx in the hvria heights upnn annealing.
The main g a l of lhic work i s tu irbricPle and invcPriprlc Ihe elactdid,
stnrctural and d a c e r n c q h ~ plm p t r u s of
InP. Tmiwn
Schol#l;y
Irycn, on
hrr W workr
is sckdbd sr t
k firs#S ~ h l k ykyar bscsuw: fi
fwccionwwelluta~ik!the~Pomrsdv~drop.Ftrrfnunr(R)&uaad
.sdwdSc&#lr).b~bccrurIthuU~rralrfenctigMd,rrtlirMI~ad
65
che metal and 1nP kyxs brfrwt und a A a mntriing. X-ray diflinwkwr (Skfm XRD
PW 3710 using Cu K, radiaii) nwwrmmtr h
m
n bum rmdr far WTi Schoaky
c~t.asto~theinWi.lmrhsbcrwbcnrhcmsali#ldInP~
Finaliy, atomic f m rnicmwqy ( A W ) her also been [email protected] ta chmfxwbthr
s u T i morphology o f rhc Wi % M y w m a s kfoh and lftrr mncrllq
I C m ~ W .
4J
Rcsrteaad DbcrPkr
43.1
Ekcrrkvl Pmp*rHn o t W 1 SrMrky Cwwctn
Onc o f the rncM uiGI? u d rncrkds ro dacnninc Ihc Schonky huricr heibt
(SBt1) of r m e t a l - x r n ~ ~ u c t rcmtact
w
i s the cumn~.\.oltagc mcawment, In ur
undopcd rcmiccmducror, rhc current I B
r S c M ) Mcr d i d (SBD) und#
C ~ I
bias roltagc V u ith the amhias cNidvc harrier height [email protected]
ia uwally dExdbed by
the thermioflir mission 1hmr)l 12 I ]
whm lo i s che ultumtion cumnt uhich ir dctcminnl
whcrc k
ib
thc Bolumcmn'r constant. 1 ir thc nhu~lutcIcmpcnlurc, A t h m~ r of thr
d i d , A' is lhc cffcctivc Hichardm cmaont,
42 is the effh'livc
Schanky M
a
height at tcro-bias MCI
n ia the idealily f ~ t mI'hc hcwcfi~~l
A* value of 9.4 ~cm"'k'
is uscd for n-type InP 1221. 7he satunr(~cmc u m l~ is m i n e d by ntnpolrthg
the lincnr region o f thc forward-bb armi.log I-V curves t t ~hrrm applied v o w
and the
+z
v a l w arc cakulared fmm 14.(4.2) tram 1%. (4.2) we can mite rti
Thc ideality fwor n is a
o f c m f a n l t y d the diudc La
pun chmnkmk
c m i s h .Rd if n ia aqwl lo onc, pure h m f m r i c milrxiarr occur, H m w , n hu
usually a nlue greater
than unity. n#: vdw of n w m detennincd Rom drc P t g ~OC
the limrr region oflhe f m d bib I-V c
m winpthc ~ I r t i O f If?ll
diodt.
The c~.eru-dmge0.-V)
duncoaiala d rbr MUn-lnP SdraltLy diakr
1 S B D j ) ~ ~ ~ o f W i n g S r s h a f t n i n f i O u r r 4 . 1 . ~ v r h w ! ~ f ~ ~
thc .r-dcpasitad WI ?Mc&y anu;r is a k a .r 0.62 cV (I-V) Ihr. n#
cnimrfed SBHs far rhs nmpks umalad u 200,300.4MI md 500 *C am 0.60 uV,
for
1Ed
20
4 . 1 :
W'cl
r
15
.ra
4 5
oo
os
wocj
ro
16
Vdtlgl, (V)
C'urmrt.vc~luge (I-V) c h u r f f f t d c ~of thc WTUn.lnP
stnrcrurc ar a funct~mof uvruling tcinpcrahur.
M
y
with incrasc in m m l i q tnnpcntum up to 400 T. Ikrwrm. Ihe burk?r [email protected]
slightly demasm w h Uw amtact is mmiod u .SO0 Y'. A maximum bankt hcig4
of 0.66 cV (I-V) u n he rchic\+d Tor cmlrc wmwk?d rr 400 "C' fur I min in
N1
atnwsphore. Fur a typical awkpmnul WII Schottky m u k leakage wwml ir
4.236.
to" A ur - I V,
w)moan
few the c c m w u\n?ikd
u 4.OQ Y', it ir obomul rhrl
thc 1ari;ayc c u m slightly dccreurs In 1.l23.10' A u .I V.
t h w , the
current is i n c h fw thc sunpk uuro&d M 5W "C' Md rhc Eurmrprmdin~v r h r IS
1,03*10'A
u
- I V. It ix fuundthdthcrcvm ~ c u m a r t d c c m a e # f n r t h o
medunbmsothahjuxtdmniank.ur:probrbtyprrscntinthesedkdwf.Ourc&tl
ckvfyM~llhrhdiakshtnidF.lirqfirmrhocisy.rer#rrhuranc.~~
nluesofidetlif).f~urpobr~durmC1~plrenriPldropinhinadLoekrya
and Ihe prsmv of cx-
cumat md the mamhinrrtian cum^
interfacial staics CS~C~WCC~
thc ~?miCQnd~~tw/InsukwIrk-
[email protected] t
k
1231. The other m ~ # n
for higher r.alu+s of ideality factor n cwM b imihurrd 10Ihc-ni
hcighr. Anothcr porsibiliry is Ihat thc ideality factor is hi*
brnier
than unity MB this may
be attribuvd la the ukidc la)= gmun an the srmicundw~cx.wpgr?&tingthrl thc
potential barriers at ml metal-xmiductru i n t d m s Jcperrd much
man!
Ihc
applicd v u l ~ g cthan predicted ihlccmlaers
f h t wries resistance R, is evoluatcd fnnn r
k S t w a d I-V mw-
winp,
a mhwfd c v z h p x l b) Cheung and Chcunp 124). '1%~Ibrwud h h c u m l - v o w
charartcristics duc to thmionic cmissiim o f r S~hotthyc a ~ l l l with
~ l h s&$
rrsistancc can hc cxprrcd as Chcimy's functi<t(lgiven by
The plot's c x ~ r i m r n t adV/d(lnl)
l
vcsur I for the difrcrrtrt nnncating t c r n ~ ~ Ist c
shown in figurc 4 2 . Iht rrtcs mkrmmcc valuer
H,
is ohtrind f m n Ihr rlapc d
range
83-715 13 for dilTcmt antreallny rcmpmtun: Ao un allcmak matrod to
nkl'lq raluc fnlni Ihc )-~ntcrccpt Ihc c~inwtlcdw i c a rchinmnce (I&)in in thc
K,
conwnt~onalohalpis, Ncdr methcwf 8s w p l o j d 1251, tn c c m p the SBii oTI"L/Ti
Schottky ccmtxt~to include thc c f l ' i t srll high wit* r c s i ~ wwhich h i n i b rhc
occuratc cvaluntian of barnet he~ghtfntm the smdurd IMl) vmu$ V plot. In thin
mnhod, a function F (V) is plottctl spinst V. F ( V ) i s givcn by
W efTmive Schottky b w h Light ir given b)
whac F(V,)
is the minimum vuluc of F(L), and V,
ia th:carrwqxmfhg v
o
w
.
ApknofF(V)vmcusVfadr~Wutdifl~tani#nturnrGlhDwn
in figure 4.3.
cxaMbd SBHs ur 0.66 eV fa udqrarhad 0.55 r V fiw 200 %
0.67 eV for 300f. 0.70 eV Ibr 400 %' and 039 eV tbt 500 06 urnorkd cumw. It b
[email protected]~dvncaboinedbyl-Vmcdrod
00
2 0 ~ 1 0 '4m10J 6 ~ 1 0 "8(bt?04t WIO'
Curtbnt (A)
P-rc
43:
Plo~so f dVldln (I) r m u s I Ea Ihe tV1'Vn-lnP Schcutky dkdr .a r
fwt~w
ofannealing rcrnpcnuwr
I
Figarc 43:
f % of
~ I;(V) vcmq V fin M i SdwJtUry cunuar lo n-lnP Mnukd .t
difftnnpentum
Capitanu-vnkge (C'-V) mexuuFmrnu ue ccnnmarrly u
e f f d v e SBH of a MS diode. d m & inmcqn crf r [email protected]
d la dcramint the
Sine h r 1 ~ vcmar
'
V
plot with the v o w u i a u n hr uncd to cllculue Ik rtktive SBN and dw: tkrpo d
the line g i m the rmiconsuxa &@ng
dauhy 1241.
[email protected]
4.4
rhowd the pkn of
w k r c A is Lhe surfrc a m of LhC dirde. r, is
thc slltk: d i c W c c l u ~ n 1#lurl fa
12.4 fur n+pc lnq28). V, is Ihr ~ I i c n\luyc,
d
N, IS
cmpcnsatcd innid
d*nmi
bciwan ( l K")vcnuv V is V,
r4
*.
the c c ~ ~ ~ n m tokf h
me nmrhe plot
11.1125~10" FIcm lhc x - i m w of
which ir rclatrd tn h i l t in prmtirlc; e I+,
4
Lf
--.
,*
P
1' i s absolute tcmperalurc. N, is rclaiwl to the nlopr of C';'vmus V. 1)le CW'W
obtained fnm Ihc c x p ~ c ~ s i o n
hc
vaslrsQpkr.nsmi#Ikw:is~innlforIbc.r-dcpadtnluvd~~4
Sdmttky aarucls.l
k Laoepr of the pkr with tbt x w i s d m dr* value ar V, Thr!
d d r c p h indiuuer a unifmn dqdng cono#rertk#l end canstant dauhy hr
imafaoc date. Thc mkul.rscl curirr cm~imlsn
of f4/Ti Wmtky
4.074*10"
3.279.10''
cm' fur thc ns+wsi~ui
mB 5.378410"
ewrt*;rt
art
cm". 3 . ~ ~ 1 omJ,
0 ' ~
cm" and 4.380~10"cm" far the con~crxannealed rr 20,300, W
500 ,T,
mpec~ircly.as Mcnnined ihmr h e slupc o f
slightly lower rhan C
JI
ud
ttK curves. Ihrm v.IUQZ UC.
hcalucr givm b> Ihr rnunufactunr. Due to &FQc&
in
miconductor and the presmc~oS&q lying impudtics <MI the dcpklms qh ths
cap#itancc can ruJr for wctifying cunurr?;.7hc vuiarim in the &oanacnmukn
with anmaling ~mpcntunran
: hc artrihu~nl10 [he cffcct of traps.
obrid
hrricr heights of Wi'i Schur&) cunmt liw os-depwitod a i d annclllcd m p k w
200. 300, 400 and 500 'C' an: 0.76. 0.73. O 78. 0,#0 Md 0.71 t V m i v c l y , It is
obwrvcd that rhc barncr height* calculm~rdfnm thc c)ipcrimcnul C-V mcoaur*mon&
art lower for thc higher doing ctmn~rtaticmas c m p l u n l to lawm cmmtlan.
Such dcpcndcnce on the doping lrrcl
crur he s x p t * d dw la
the c l c & c HsM
drpmdcnce of ~k
d i j u ~ kla)w k m m rhc xmiconducIcr and the meul. Tabk 4.1
shows thc values of Schtd&) h i c r heights (1.V. No&
a d C-V), rcvenic- 1
c u m n ~ ikality
,
factors and vcriicc t a i s t m fiw *u&y*siccil
and uurubd Wf
Schottky contacts.
In onler to compur rhc bamcr height* thal art dtainnt fram I-V, Narde m d
C-V rnethcds. a plot drnun bctwan lhc hsrricr hcighln and nnirc~lingts?mprrrtumLO
shown in figurr 4.5.11 can hc wen clearly (rum fipuw 4.5 thirt thc b k t bight dlhc
Wl i Schottk) d i d impmrtd upm snmaltnp nt 400 "C'. Hnvvcvrr, thm is a dlg)llly
dccrcaw of SRti o f Wli Schnttky cmtact aflcr onnerlhp ar 300 T. Ihc m m
satisfking mwlt o h i n e d here i s the contact anmiling at IOQ *C with ideality fncW of
1.14 and 0 W uf0.66 CV (1-V) ad 0.80 cV (C'-V), According lo thc f-V, Nordc md CV messurrments, the vwinjon in the Rtlr aS MISchottky conuct a h mncr)&
H I ~ S ~ Sthat
I
Mi films may nrct rrilh fnP. IhB is lonfinncd by A&S ud XRD
exuninatiw. It can dw k v a ~ nfmm figm 4.5 the CLV E W V g~ a bcrtkl
~
hdcrt#
vnlucs hiegKI lhur t h e drriwxf f i 1.V I I W U W ~ . The n r w ~
fw Ihc
dixbctwaen the I-V urd C-V mavYnd SOHI wu ~ p W t # d f d h . $ 4 ~
Ulc I-V mdhod inrolwa the fbw ar -Q
fnmt
mbawtuaw lo mad. cka
~hci&dcvmrinaclfmchirmakrdvlll~tyysarcldrkmrkntsr
rhc i n t c r f r l l mi& k>w complsiticm, m-unifurmi~of h i n k y f r l l hy~r
ud distribution ctf u r d w U chugm a n *In) curn rudr dlflriwnoa In rbs
thick-
barrier [email protected] dcmmincd mWn I-V md Il'.V rcchniyucl.
ideality f r t ~ x(n) *nd miw mi.stmcc nt' WI !+&ttky
InP 6s r function irf mncalmg m p a l u n
-**-
------ .-----------
Sampk
(Y')
*
i&.pecvmr
di&
an n-
----**----*.*-**----**-----------
Schc1tky W h e i g h t
at - l bolt
csnlir :4
I-V
Ncadc
(rV)
C'-V
Ideality
filar
'n'
Sda
rarJBIlrrnwl
R(ni
133 S b . e b n r l . . d N a r p k J g l M P m p w U m d P V l l ~ C a c r l r g
nKPtViwmunnlaucisa~lkwdbyAu~ckFaonrpahas;gry(AES)
kpch pjlk in ordc*tu mm-tk
Wotr 8nd
inwmixingaldk: & a d
lftcr w#ri'i H 500 T.Figwe 4.qrHc) h w s liK, A-
InP hysa
qwUm depth
pfikrrsuluubPindfwrht~rcdiOaP'onlMW)TMne*kdrm~.
The mutts show
aft% ammaling. AS
chnges in Ihc mct.lliapim
be r e n fmm figwe 1.6(r).d#: ctsdcpasiurl Irqcrw cxhtbh r mlrrivcly sharp ilwosbce,
indicating tbc dmmw of inicrdiRitEicn into 1nP. For the mnpk uu#rbd ai 100 T
figure 4.Mh). a m a l l mmmt of indium is oucdiffitdina~dw: nrPI layem. lhir is
la mrts witb PI and Ti rann 8. and Ti-In inmmmlalk
indicatingthe ptmibilhy
y, fipm
4 b(c) II is obwvd W same unount of i d t w n (In) ir. w#Bl&ayl i r ~ t
uh d
layem. tiowcver. it is noted hat a matt MHWM of pimphide i a dw o~.dltlLmdhhu
the metal layer% which tndiutes thc f m a h or pkmphidc phuce ai thr
compounds during amwaling kmpmr~mFrr Ihc m p k urnaid at 500
I
0
-
.
-
rQO
.
*03
-
.
1
Sprttlzr time (Sac)
-
L
I
mrre 4.4:
-
.
-
&
tm
rsoo
Sputm time (See)
Augcr [email protected] p
fik of thc W 1 1 !khttky mlwls ta n*InP. ( 8 ) r9dcywnitml. (b) a ~ u r l c du 4OU y' u*l Ir) mitcakd11 SO(I 'OC'.
o
rrx,
In cmh 14) cmfinn fwthcr thc inrr*frirl rruflicwra between the maul uwf InP
layas during mpid lhcmul m n a l i n y
(HlA). XRI)
m a w r r m # ~we
~
prrlinnad.
Figure 4.7 shows the XHD plrns of t i l i FchnnLy c c m u ~ l j Figure
.
4.7fa) show rhr
X R I I pkM crf thc ~r-kpnitd
umpk. In dditum u
v the chrrclcriaPk. pcah of
( I I 1). (222). rhccr uc cxher @ s
c
h
In&,r(555). For thc ccn~ccutwM tr
InP
d uttwh ur dqnifiml as I l r , t ~(&I) nd
HK)
%'. figrurr: 4 7fb). dditirml p d n n
l~bscrvadcompared with tlw or t!ac aHkspmr(rd mc, l
k phwcrr iue kknlilkwl u
imficaii\c of rhc fwmmum nf n m incnfwral phkm. u crpwtcd Pmn AES [email protected]
pmfilc [figure 4.Mb)). A n n urnaliny .t 500 "C'. fiw 4 7(c), exba p&S
M!
~cctindditiuntoIhepc.L~nbszrvnlmkuaEpnlt#lurd4o~"uvuylrpd
uunpk, which indW Ihe fonnr;tm d new h&rthinl
h t i f i e d as 'lii,7Plo(31 I ) and I
pha#r. Them phuta m
'lhc n t m t c f m e mkn~c.ctm(Af"M) is cmplcryed II, chasaclmits thc &ace
mcarphob~of lhc Wl i Schottky cantacts befan: wd
uuruling ri 500 *C. A M
imagcs of the Wl'i Suhottky contact f' Lhc ar.dclmit6d dm m M af 400 *C, 1100
'
C arc shawn in figurn 4.8. lRe scanned ur* of the m p l e is I * lw3.7he xurfvPc
morgholug) of the rwlqmitcd W17 % M y mtrd in frWy mardr with a mmean-squrur (RMS) nnrghncaa of 0,477 tm u$ dmrm In flw 4,Rr). Whcn thp
4110 "0,
figure 4.&(bj, lJIc ~ r C j r rmarphobaOy of lhr WT1
contact is enncrkd
Schonlry conw is dighub irnpved with r RMS ~ p h n c r rof 0.638 nm. With
funhcr incrauc in annealing IcmpentuIL up to 500 r.figum J.l)(c). it ir abwrwd
ch.ldwswT~ccmorphoCgyof~vrwrcrrisdifitly~EodwhhrRMS~
ofO.693m.scompFcd~oIheurbc(wniled#Id400"r;"rnnalrd~.~
rrnrttsWicrselh#rtwW]7SchPnkyeanuakmaocrudi~~~lhtnmrl
~ h u i n g u # * r l i n g ~ ~
Ithwllb~11~rrshrtthrinaniictxlr~1mdchemiut~kdmrcar
rhe nmal-raaicarrdulnr surhEa ma) pk) m imponant mlr in doraminlw drc!
e L a ; W popurics or rhc &vices.
7hr i m p m d SchmA) hniaM i of the WTI
contact upon a m d i n g cwM be IruriW to Ihc hmfaciai raocrhn aocumng h w c a
mebl and InP h~~ Awarding to the w h s o f AES wd XRD. the ucn.difis9on
at
thc indium (In) f m IIU
InP into M
i lajm uld plniciplucJ in thc fwnunian d
indium phases
-
a(
the intnrfe. Ihc f w m a t h o f In3H (1 I l k Tillnr (220), Pllviw
i 201 1. Rlln?(1 16). In)& (Mlh R\:lnc, ( b l )uwl lrruR~t(SSir)(as shown hy XHD
in figurr 4 7(h)). ~ h i c h1 4 s to Ihc clruumuflLiun of ind~umv ~ k o u
o t
h InP
wrfare region. As a rcsulr, the ancrrar In q n I i r c chrycs U the i n t d dun
~
w b l ) arix due to tln-tmm
tnp5
Irx'altr4 m h e 1nP surf=.
This induces m
i n c m in the valuc of ltrc Siltis u f ' h Rfl i S c W ) c t w w c~tnw.tedhm I)n: t-V
characrristlrs for thc ccwuct rnmtnlnf af 4 0 *l' A t k n k posdbiliry ia
rM {L
~ncrraxit\ harrier height mi& he duc tir I ~ Fductiim af'rac~-~~ichkunc~rk:
&fa
in the metallurgicrl intcdaec (341. T h e rrywn tntalving the &frets cm he mid
due to JIC
intcr-diflusicm of metal tntn JnP lk prcrncc of thcsf phaw?r
at the
iniwfacc causes the v a r h r In Icahp current. lh incrcrsf in the SBil is dwp
eccompnicd by a cmsponding mfucricm in the mrrsc kubgc cwnml. This
findlng is ct~nsiqcnfw~rhthc rrwltr prcvimtl) rnpmtd by lIh&JLOTROddy C1 d (351
and lanardhnnem a a1 (3ttj. Ihry rcpcwtcd that the fmmrtinn of indium phaaer
Ihe
intcrfxc c ~ ~ l hC
l dthe mexm fix IWFC(LVof 'SI#lfsupon nnncrling ~rmpwatm?.At Iha
500 "C annealing tempslr~tu~.
chr: p f r l m l t a l c ~ t - d i f f u dof~W
~leadr
W
lo r S
IWoi' P from rhc surfwc and loas P fnmt Lhc urrfwe may W fu chuIgc in the
in~crfwcw e dcnsct) distrlhul~tm In ~ h cam
~ s r pmitivc charge state may aim u
rhc tnvrfscc duc to Im%
of phoqhmur fnm $la:w f i . This m y rcdw the hnlef
height in the 500 "C urncalal w p k t h ~~p u o t tol I)K" 400 *C ~ t ~ l LI~II*.
a d
Aceording lo Ihbor c4 a1 /37] tho knnr vdue of
thc burirr heiphl fa Wnpk
mnakd at highn kmpcmtwe un k aUribrtm.4 W d w 3 b in chc dcndty of
inlerfrial & f ~Alw.
. the m h ban faund t h t (hc F m i lmtt at mduY<PIIN
interhcc~is pinned by defects. Thc modifruka, of chc Mrdt W
t
y by m l h g
could change thc pEnniny uf thc F n m ~lwei wh# *aokl mkd in c h p of It#
barricrMgtfl.Von&Walk~ri[38Jhi~h~h~heiphcdunlp
foramrlad I n a d M h A x SBUs by*
~ m d k n # ~ v r i u c J
m ~ b c t w o c ndKequ~librlunbliwhcc
Rdwma
Y. Lnrj. T. Ishibashi. a d M. Idc LEE EkEtmnic dcvh. MI. EDL 2,67
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