EIocIrophysicaI proporIios

of moIaI-somiconducIor-moIaI sIrucIuros basod

on isovaIonIIy dopod zinc soIonido crysIaIs
O.Chugoi

, V.Rqzhihou, N.8|orzhinehiq,
8.Oleqnih

, K.Ko|runou, I.Zenqo
STC InsIIIuIo or SIngIo CrysIaIs, InsIIIuIo or ScInIIIIaIIon MaIorIaIs,
NaIIonaI Acadomy o ScIoncos o UkraIno,
60 LonIn Avo., 61001 KharkIv, UkraIno

N. Zhukovsky NaIIonaI Aorosaco UnIvorsIIy KhAI,

1? ChkaIov SI., 610?0 KharkIv, UkraIno
FeceiteJ z7 Jul, z003
EIocIrIc caacIIanco C and dIoIocIrIc Iossos Ig havo boon doIormInod or moIaI-somIcon-
ducIor-moIaI sIrucIuros basod on IsovaIonIIy dood ZnSe crysIaIs. II has boon shown IhaI
annoaIIng o Iho grown crysIaIs In zInc aImoshoro causos Iho Incroaso o C by 2-3 ordors
o magnIIudo. ThIs aramoIor, as woII as Ig bocomos doondonI uon Iho bIas voIIago U,
wIIh rogIons o nogaIIvo and o osIIIvo sIoo obsorvod on Iho C(U) IoIs. II has boon
shown IhaI doondoncos C(U) and Ig(U) aro doIormInod by changos wIIh voIIago In Iho
Iwo oosIIoIy swIIchod SchoIIky barrIors.
HccAoonanw aAox1oomxoc1 C u 1anonc yAa uaAox1uocxux no1o Ig c1yx1y
mo1aAA-noAynononux-mo1aAA na ocnono uaonaAon1no Aouonannwx xuc1aAAon ZnSe.
Vc1anonAono, 1o o1xu xuc1aAAon n a1mocqoo unxa oycAonAunao1 ynoAuonuo C na
2-3 nonxa. Haamo1w C u Ig c1anonn1cn aanucnmumu o1 cmomamoo nannxonun
U, nuom n aanucumoc1u C(U) naAa1cn yac1xu xax c o1ua1oAnwm, 1ax u c
noAoxu1oAnwm naxAonom. Hoxaaano, 1o aanucumoc1u C(U) u Ig(U) onooAn1cn
uamononuom c nannxonuom nyx, nxAonnwx nanc1oy y yy, aoon Ho11xu.
EIocIrIc caacIIanco C and dIoIocIrIc
Iossos Ig havo boon doIormInod or moIaI-
somIconducIor-moIaI sIrucIuros basod on
IsovaIonIIy dood ZnSe crysIaIs. II has boon
shown IhaI annoaIIng o Iho grown crysIaIs
In zInc aImoshoro causos Iho Incroaso o C
by 2-3 ordors o magnIIudo. ThIs aramo-
Ior, as woII as Ig bocomos doondonI uon
Iho bIas voIIago U, wIIh rogIons o nogaIIvo
and o osIIIvo sIoo obsorvod on Iho C(U)
IoIs. II has boon shown IhaI doondoncos
C(U) and Ig(U) aro doIormInod by changos
wIIh voIIago In Iho Iwo oosIIoIy swIIchod
SchoIIky barrIors.
IsovaIonI doanIs InIroducod InIo zInc
soIonIdo crysIaIs aro known Io orm assocI-
aIos wIIh Iho InIrInsIc sIrucIuro doocIs.
ThIs causos subsIanIIaI changos In Iho soc-
Irum o chargo carrIor IocaIIzod sIaIos and,
as a consoquonco, ImrovomonI o Iho IumI-
nosconI roorIIos [1. CIosoIy roIaIod Io
oInI sIrucIuro doocIs aro aIso dIoIocIrIc
roorIIos o Iho crysIaIs, o.g., dIoIocIrIc
Iossos [2 or dIoIocIrIc roIaxaIIon [3. Thoro-
oro II couId bo oxocIod IhaI InIroducIIon
o IsovaIonI doanIs wouId aIIow conIroI o
oIocIrohysIcaI and, In arIIcuIar, o dIoIoc-
IrIc aramoIors o Iho saId crysIaIs, condI-
IIonIng IhoIr aIIcaIIon In varIous IochnI-
FuncIIonaI MaIorIaIs 11, No.4 (2004) 2004 - InsIIIuIo or SIngIo CrysIaIs
6S4 Func|ionol no|eriole, 11, 4, z004
caI dovIcos. Howovor, oocIs o IsovaIonI
doanIs uon Iho dIoIocIrIc rosonso, as ar
as wo aro Inormod, has noI yoI boon sIud-
Iod. CarryIng ouI such sIudIos was Iho rIn-
cIaI uroso o Iho rosonI work.
Wo havo sIudIod ZnSe, ZnSe(Te) and
ZnSe(O,Te), grown rom Iho moII undor
hIgh argon rossuro usIng Iwo dIoronI
IochnoIogIos. ThIs onabIod us Io obIaIn scIn-
IIIIaIors o Iwo Iyos. ScInIIIIaIors o Iho
IrsI Iyo (I) woro roarod rom ZnSe(Te)
crysIaIs, as woII as ZnSe crysIaIs grown
usIng Iho sIandard IochnoIogy. Thoy aro
characIorIzod by hIgh IIghI ouIuI (u Io
140 % wIIh rosocI Io CsJ(Tl)), IumInos-
conco socIra wIIh maxImums aI 630-
640 nm, and docay IImos roachIng -100 ms.
Tho roaraIIon IochnoIogy o ZnSe-basod
scInIIIIaIors o Iho socond Iyo (II) Is ro-
IaIod Io crysIaI growIh undor addIIIonaI
doIng wIIh oxygon. Such scInIIIIaIors havo
Iowor IIghI ouIuI and smaIIor docay IImos.
Tho maxImum o Iho IumInosconco socIrum
Is shIIod Iowards shorIor wavoIongIhs
(
nor
600-610 nm). AIor growIh, somo
o Iho samIos woro annoaIod In zInc aImos-
horo In vacuum-soaIod quarIz amouIos aI
1290 K durIng 24-48 hours.
Tho conconIraIIon o IoIIurIum was do-
IormInod by scannIng oIocIron mIcroscoy
wIIh X-ray mIcroanaIysIs usIng an ISM-820
oIocIron mIcroscoo wIIh a ZInk AN10185S
mIcroanaIysIs sysIom (EMPA-oIocIron-robo
mIcroanaIysIs). Tho doIormInaIIon accuracy
was 0.30.5 mass %. EIocIrohysIcaI moas-
uromonIs woro carrIod ouI on 553 mm
3
Iargo samIos. OnIo Iho Iargo sIdos, oIocIrIc
conIacIs woro aIIod In Iho orm o nGa
ouIocIIcs, Ihus ormIng a moIaI-somIconduc-
Ior-moIaI (MSM) sIrucIuro. MoasuromonIs
o Iho caacIIanco C and dIoIocIrIc Iossos
Ig o Iho sIrucIuro woro carrIod ouI In Iho
Iow-roquoncy rango usIng a R589 AC
brIdgo, and In Iho hIgh-roquoncy rango -
a EM 560 Q-moIor.
WIIh any doanI comosIIIon, In Iho
Iow-roquoncy rango oIocIrIc caacIIanco o
MSM-sIrucIuros basod on non-annoaIod
ZnSe crysIaIs dId noI oxcood sovoraI F,
whIch Is In agroomonI wIIh Iho known vaI-
uos o Iho dIoIocIrIc consIanI or undood
crysIaIs [4. DIoIocIrIc Iossos aro aIso raIhor
Iow (Ig-10
-2
). EoIh aramoIors aro woakIy
doondonI uon IomoraIuro and Iho oIoc-
IrIc IoId roquoncy. An ossonIIaI oaIuro o
Iho dIoIocIrIc rosonso o sIrucIuros basod
on annoaIod ZnSe(Te) and ZnSe(O,Te) crys-
IaIs Is unoxocIodIy hIgh vaIuo o IhoIr ca-
acIIanco, whIch roachod 2 nF In sovoraI
samIos. WIIh IhaI, avorago vaIuos o C or
ZnSe(O,Te) - basod sIrucIuros woro much
Iargor Ihan Ihoso obsorvod or ZnSe(Te)
crysIaIs. Howovor, Iho avorago Ig vaIuos o
Iho saId sIrucIuros aro roIaIod by an Invorso
roIaIIonshI.
To cIoar u Iho naIuro o hIgh o-
IarIzabIIIIy o MSM-sIrucIuros, wo havo
moasurod IhoIr voII-caacIIanco charac-
IorIsIIcs (VCC). Doondonco o C and Ig
uon Iho aIIod voIIago U wouId IndIcaIo a
subsIanIIaI roIo o oIocIrodo-ad]aconI oIon-
IIaI barrIors In Iho rocoss o oIocIrIc o-
IarIzaIIon o Iho sIrucIuro. In acI, oIocIrIc
caacIIanco and dIoIocIrIc Iossos o Iho
sIrucIuros on Iho basIs o annoaIod
ZnSe(Te) and ZnSe(%0) samIos doond
uon Iho vaIuo and oIarIIy o Iho aIIod
bIas voIIago. A IyIcaI aoaranco o such
IoIs or Iho oosIIo oIarIIIos o Iho bIas
voIIago Is shown In FIg. 1. CharacIorIsIIc
oaIuros o Iho shown C(U) doondonco Is
Iho rosonco o rogIons wIIh osIIIvo or
nogaIIvo sIoo aI Iow and roIaIIvoIy hIgh
voIIagos, rosocIIvoIy, as woII as dIoronI
doondoncos or oosIIo dIrocIIons o Iho
aIIod IoId. Howovor, Iho Ig(U) doond-
FIg. 1. TyIcaI doondoncos o oIocIrIc caacIIanco (1) and dIoIocIrIc Iossos (z) o MSM sIrucIuros
on Iho basIs o crysIaIs ZnSe (a) and ZnSe(Te) (b) uon Iho bIas voIIago.
O.Chugoi e| ol. , Elec|ropheicol proper|iee o] ...
Func|ionol no|eriole, 11, 4, z004 6S
onco Is noI subsIanIIaIIy changod whon o-
IarIIy o Iho bIas voIIago IoId Is rovorsod.
Ono shouId noIo IhaI asymmoIry o Iho C(U)
IoIs Is roroducod uon romovaI and sub-
soquonI now aIIcaIIon o Iho oIocIrIc con-
IacIs uon Iho samIos; IhIs asymmoIry Is
characIorIsIIc or aII sIrucIuros on Iho basIs
o annoaIod crysIaIs. II Is ImorIanI Io noIo
IhaI Iho caacIIanco and dIoIocIrIc Iossos o
MSM-sIrucIuros basod on annoaIod ZnSe
crysIaIs aro aIso doondonI uon Iho bIas
voIIago (FIg. 1,b). Howovor, In IhIs caso Iho
obsorvod changos In Ihoso aramoIors aro by
noarIy Iwo ordors o magnIIudo Iowor Ihan
In Iho caso o Iho abovo-doscrIbod sIruc-
Iuros.
Tho suraco o zInc soIonIdo crysIaIs Is
known Io bo covorod by a IhIn oxIdo IIm.
Thorooro, whon Iho samIo Is Iacod bo-
Iwoon Iho Iwo oIocIrodos, Iho rosuIIIng
sIrucIuro can bo caIIod moIaI-dIoIocIrIc-
somIconducIor-dIoIocIrIc-moIaI (MDSDM).
In such sIrucIuros, VCC mInImum has boon
roorIod aI U 0 [5, whIch doos noI agroo
wIIh our oxorImonIs. Honco, Iho oocIs o
Iho oxIdo IIms uon Iho abovo moasuro-
monI rosuIIs may bo nogIocIod, and wo can
IroaI ZnSe(O) and ZnSe(O,Te) crysIaIs wIIh
oIocIrodos as sIrucIuros moIaI-somIconduc-
Ior-moIaI (MSM). In oIhor words, Iho
sIrucIuros sIudIod aro, In acI, Iwo SchoI-
Iky dIodos swIIchod In muIuaIIy oosIIo dI-
rocIIons.
Tho AC brIdgo R589 usod In our moas-
uromonIs InvoIvod Iho araIIoI subsIIIuIIon
schomo o Iho ob]ocI (FIg. 2,a). Tho dIrocIIy
moasurod vaIuos aro oIocIrIc caacIIanco
and Ig o Iho ob]ocI
Ig =
1
FC
,
(1)
( = 2]). NogIocIIng crysIaI voIumo oocIs
uon VCC o Iho MSM sIrucIuro, IIs oquIva-
IonI oIocIrIc dIagram can bo rosonIod as
Iwo sorIos-connocIod F-C-chaIns (FIg. 2, b).
Each o Iho chaIns corrosonds Io a SchoI-
Iky barrIor aI Iho moIaI-somIconducIor
boundary. Tho caacIIancos o Iho doIoIod
boundary Iayors aro C
1
and C
2
, rosocIIvoIy.
II shouId bo noIod IhaI whon Iho bIas voII-
ago aIIod Io Iho sIrucIuro Is Incroasod,
ono o Iho caacIIancos wIII bo IncroasIng,
whIIo Iho oIhor wIII docroaso. AssumIng
IhaI F
1
and F
2
aro oquaI, Iho oquIvaIonI
caacIIanco o Iho sIrucIuro, doInod by
connocIIon In sorIos o C
1
and C
2
C =
C
1
C
2
C
1
+ C
2
(2)
wouId aIso docroaso. Such bohavIor o C(U)
was acIuaIIy obsorvod In Iho rogIon o woak
bIas voIIago IoIds (soo FIg. 1). Howovor,
uon urIhor rIso o U, Iho caacIIanco o
Iho MSM sIrucIuro Incroasos. ThIs can bo
oxIaInod by Iho oocIs o rosIsIIvIIy o Iho
doIoIod Iayors, whIch, docroasIng wIIh rIs-
Ing U, shunIs Iho IowosI caacIIanco o Iho
MSM sIrucIuro.
To chock u Iho abovo assumIIon,
maIhomaIIcaI modoIIng o Iho C(U) uncIIon
was carrIod ouI or a MSM-sIrucIuro. II was
assumod IhaI Iho rosIsIanco o oach o Iho
doIoIod Iayors Is a uncIIon o voIIago do-
IormInod by Iho oxrossIon:
F = F
0
ox(bU),
(3)
whoro b Is a consIanI.
As U Is an aIgobraIc vaIuo, Iho voIIago
aII on oach o Iho barrIors (U
1
and U
2
,
rosocIIvoIy) was caIcuIaIod by IIoraIIons
carrIod ouI or oach vaIuo o Iho aIIod
voIIago U. U
1
and U
2
IhaI had boon Ihus
doIormInod woro usod In caIcuIaIIons o Iho
doIoIod Iayor caacIIanco [6
C
i
=
e
0
N
J
2

\
b
\
i

hT
e

,
(4)
whoro e Is Iho oIocIron chargo,
0
- dIoIoc-
IrIc consIanI, - dIoIocIrIc ormIIIIvIIy o
Iho crysIaI, N
J
- conconIraIIon o Iho
donor doanI, \
b
- bondIng o zonos In Iho
doIoIod Iayor rogIon, h Is Iho EoIIzmann
consIanI, and T Is Iho absoIuIo IomoraIuro.
FIg. 2. EquIvaIonI oIocIrIc subsIIIuIIon dIa-
grams o Iho moasuromonI ob]ocI (a) and
MSM-sIrucIuro (b).
O.Chugoi e| ol. , Elec|ropheicol proper|iee o] ...
6S6 Func|ionol no|eriole, 11, 4, z004
Tho oquIvaIonI caacIIanco o a MSM sIruc-
Iuro Is doscrIbod by oxrossIon
C =
2

C
1
1
F
1
2
+
2
C
1
2
+
C
2
1
F
2
2
+
2
C
2
2

1
.
(5)
Tho oxrossIon or Iho oquIvaIonI rosIs-
Ianco o a MSM-sIrucIuro has Iho orm:
F =
F
1
1
F
1
2
+
2
C
1
2
+
F
2
1
F
2
2
+
2
C
2
2
.
(6)
Tho modoIod uncIIons C(U) and Ig(U)
aro shown In FIg. 3. AarI rom Iho IowosI
voIIago rogIon or C(U) and Iho hIghosI
voIIago rogIon or Ig(U), Ihoso uncIIons
aro quaIIIaIIvoIy sImIIar Io Ihoso obsorvod
oxorImonIaIIy (c. FIg. 1 and FIg. 3).
Among ossIbIo roasons or Iho rIso o Ig
In Iho hIghosI voIIago rogIon aro IonIzaIIon
Iossos, whIch woro noI accounIod or In Iho
modoIIng. Tho quosIIon o dIscroancIos bo-
Iwoon oxorImonIaI and caIcuIaIod C(U) do-
ondoncos aI Iho IowosI voIIagos roquIros
urIhor sIudIos, IncIudIng sIudIos o Iho dI-
oIocIrIc rosonso o Iho crysIaI.
In our oInIon, a sub]ocI o a soaraIo
sIudy can bo Iho asymmoIry o C(U) and
Ig(U) (soo FIg. 1). As shown by addIIIonaI
sIudIos, Iho asymmoIry o Ihoso curvos Is
accomanIod by Iho doondonco o Iho voII-
ago-curronI characIorIsIIcs uon oIarIIy o
Iho aIIod voIIago (FIg. 4). In rIncIIo,
Ihoso asymmoIrIos can bo oxIaInod assum-
Ing Iho rosonco o gradIonIs o somo hysI-
caI aramoIors dIrocIod normaIIy Io Iho sur-
aco. Howovor, IhIs assumIIon doos noI
agroo wIIh Iho rosuIIs on Zn dIsIrIbuIIon
roIIo sIu dIos In Iho annoaIod zInc soIonIdo
crysIaIs, as woII wIIh Iho acI IhaI Iho
asymmoIry o characIorIsIIcs Is obsorvod aI
any orIonIaIIon o Iho samIo suraco wIIh
rosocI Io Iho IngoI suraco.
ConcIudIng, II can bo noIod IhaI MSM-
sIrucIuros basod on annoaIod ZnSe(Te) and
ZnSe(Te,O) crysIaIs havo non-IInoar voII-
amoro characIorIsIIcs roIaIod Io Iho orma-
IIon o SchoIIky IransIIIons. ConIroI o Iho
caacIIanco o such sIrucIuros by moans o
oxIornaI voIIago aIIows subsIanIIaI broadon-
Ing o Iho uncIIonaI ossIbIIIIIos o non-o-
IarIzIng doIocIors o IonIzIng radIaIIon IhaI
aro boIng dovoIood on Iho basIs o broad-
band somIconducIors [?.
Rejerencee
1. L.V.AIroschonko, S.F.Eurachas, L.P.OaI`chInoI-
skII oI aI., CrysIaI ScInIIIIaIors and DoIocIors
o IonIzIng RadIaIIons on ThoIr Easo, KIov,
Naukova Dumka (1998) [In RussIan.
2. F.Krogor, Tho ChomIsIry o ImorocI Crys-
IaIs. PhIIIs Rosoarchor IaboraIorIos, EInd-
hovon, Tho NoIhorIands, NorIh-HoIIand
PubIIshIng Comany, AmsIordam (1964)
3. U.M.PoIavko, PhysIcs o DIoIocIrIcs,
Vysshaya ShkoIa, KIov (1980) [In RussIan.
4. A.A.EIIsIanov, V.S.Eondaronko, V.S.ChkaIova
oI aI., AcousIIcaI CrysIaIs, Nauka, Moscow,
(1982) [In RussIan.
5. N.F.KovIonIuk, EIocIronIc EIomonIs on Iho
Easo o SIrucIuro SomIconducIor-DIoIocIrIc,
Enorgy, Moscow, (19?6) [In RussIan.
6. S.M.Szo PhysIcs o SomIconducIor DovIcos. A
WIIoy-InIorscIonco PubIIcaIIon. John WIIoy
Sons, Now York, ChIchosIor, ErIsbano,
ToronIo, SIngaoro (1981).
?. P.O.KashorInInov, A.N.LodygIn, S.S.Mar-
Iynov, V.S.Hrunov, Fi:. Tehhn. Poluprot., 33,
14?5 (1999).
FIg. 3. EIocIrIc caacIIanco (1) and dIoIocIrIc
Iossos (z) as uncIIon o Iho bIas voIIago,
obIaInod as a rosuII o modoIIng.
FIg. 4. A IyIcaI voIIago-curronI charac-
IorIsIIc o MSM sIrucIuros on Iho basIs o
ZnSe(Te,O) crysIaIs.
O.Chugoi e| ol. , Elec|ropheicol proper|iee o] ...
Func|ionol no|eriole, 11, 4, z004 6S7
EAouvpoqianni nAacvnnocvi cvpyuvyp
movaA-naninnponinnu-movaA na ocnoni iaonaAonvno
Aoonannx upncvaAin coAoniy nnuy
O.Hqo, B.Puxuuoo, H.Cmopxuncuu,
C.Oninuu, K.Kompqnoo, I.3enn
ocAIxono oAox1oomnIc1 C u 1anonc xy1a IoAox1unux n1a1 Ig c1yx1y
mo1aA-nanInnonInux-mo1aA na ocnonI IaonaAon1no Aoonanux xuc1aAIn ZnSe. Ec1anon-
Aono, mo nInaA xuc1aAIn y cooonumI unxy oymonAo aIAonnn C na 2-3 non-
xu. Haamo1u C I Ig c1a1 aaAoxnumu nI amImyoI nanyu U, nuomy n aaAox-
noc1I C(U) cnoc1oIa1cn oAac1I nx a noa1unnum, 1ax I a noau1unnum naxuAom.
Hoxaaano, mo C(U) I Ig(U) nuanaa1cn aaAoxnIc1 nI nanyu nox a`oIn Ho11-
xu, mo nnImxnono naayc1I oun onomy.
O.Chugoi e| ol. , Elec|ropheicol proper|iee o] ...
6SS Func|ionol no|eriole, 11, 4, z004