Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor
Electronic band structure of the diluted magnetic semiconductor Cd₁₋x Mn x Te [100] ideal surface is calculated by the semiempirical tight- binding method in the framework of sps*-model. Surface bands, emerging above the bulk band structure, as well as their type, energy position and...
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| Cite this: | Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor / S.V. Melnichuk, Y.M. Mikhailevsky, I.M. Rarenko, I.M. Yurijchuk // Condensed Matter Physics. — 2000. — Т. 3, № 4(24). — С. 799-806. — Бібліогр.: 12 назв. — англ. |
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irk-123456789-1209852017-06-14T03:03:07Z Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor Melnichuk, S.V. Mikhailevsky, Y.M. Rarenko, I.M. Yurijchuk, I.M. Electronic band structure of the diluted magnetic semiconductor Cd₁₋x Mn x Te [100] ideal surface is calculated by the semiempirical tight- binding method in the framework of sps*-model. Surface bands, emerging above the bulk band structure, as well as their type, energy position and localization near the parting border with vacuum are investigated. It is shown that Mn 3d-states as well as sp-states play appreciable role in the formation of surface bands. The peculiarities of surface band structure are analyzed in the dependence of solid solution composition. Розраховано електронну зонну структуру iдеальної поверхнi [100] напiвмагнiтного напiвпровiдника Cd₁₋x Mn x Te в sps*-моделi сильного зв’язку, що включає катiоннi d -орбiталi. Вивчено зони поверхневих станiв, якi виникають на фонi спектра об’ємного кристалу, їх тип, енергетичне положення та просторову локалiзацiю бiля границь роздiлу з вакуумом. Показано, що поряд з sp -станами помiтну роль у формуваннi поверхневих станiв вiдiграють 3d -стани Mn. Аналiзуються особливостi спектра поверхнi залежно вiд складу твердого розчину. 2000 Article Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor / S.V. Melnichuk, Y.M. Mikhailevsky, I.M. Rarenko, I.M. Yurijchuk // Condensed Matter Physics. — 2000. — Т. 3, № 4(24). — С. 799-806. — Бібліогр.: 12 назв. — англ. 1607-324X DOI:10.5488/CMP.3.4.799 PACS: 73.20 http://dspace.nbuv.gov.ua/handle/123456789/120985 en Condensed Matter Physics Інститут фізики конденсованих систем НАН України |
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Electronic band structure of the diluted magnetic semiconductor
Cd₁₋x Mn x Te [100] ideal surface is calculated by the semiempirical tight-
binding method in the framework of sps*-model. Surface bands, emerging
above the bulk band structure, as well as their type, energy position and localization near the parting border with vacuum are investigated. It is shown
that Mn 3d-states as well as sp-states play appreciable role in the formation
of surface bands. The peculiarities of surface band structure are analyzed
in the dependence of solid solution composition. |
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Article |
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Melnichuk, S.V. Mikhailevsky, Y.M. Rarenko, I.M. Yurijchuk, I.M. |
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Melnichuk, S.V. Mikhailevsky, Y.M. Rarenko, I.M. Yurijchuk, I.M. Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor Condensed Matter Physics |
| author_facet |
Melnichuk, S.V. Mikhailevsky, Y.M. Rarenko, I.M. Yurijchuk, I.M. |
| author_sort |
Melnichuk, S.V. |
| title |
Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor |
| title_short |
Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor |
| title_full |
Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor |
| title_fullStr |
Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor |
| title_full_unstemmed |
Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor |
| title_sort |
band structure of [100] surface of cd₁₋x mn x te diluted magnetic semiconductor |
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Інститут фізики конденсованих систем НАН України |
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2000 |
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http://dspace.nbuv.gov.ua/handle/123456789/120985 |
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Band structure of [100] surface of Cd₁₋x Mn x Te diluted magnetic semiconductor / S.V. Melnichuk, Y.M. Mikhailevsky, I.M. Rarenko, I.M. Yurijchuk // Condensed Matter Physics. — 2000. — Т. 3, № 4(24). — С. 799-806. — Бібліогр.: 12 назв. — англ. |
| series |
Condensed Matter Physics |
| work_keys_str_mv |
AT melnichuksv bandstructureof100surfaceofcd1xmnxtedilutedmagneticsemiconductor AT mikhailevskyym bandstructureof100surfaceofcd1xmnxtedilutedmagneticsemiconductor AT rarenkoim bandstructureof100surfaceofcd1xmnxtedilutedmagneticsemiconductor AT yurijchukim bandstructureof100surfaceofcd1xmnxtedilutedmagneticsemiconductor |
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2025-07-08T18:58:21Z |
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2025-07-08T18:58:21Z |
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Condensed Matter Physics, 2000, Vol. 3, No. 4(24), pp. 799–806
Band structure of [100] surface of
Cd1−xMnxTe diluted magnetic
semiconductor
S.V.Melnichuk, Y.M.Mikhailevsky, I.M.Rarenko, I.M.Yurijchuk
Chernivtsi State University,
2 Kotsiubinsky Str., 274012 Chernivtsi, Ukraine
Received December 12, 1999, in final form April 21, 2000
Electronic band structure of the diluted magnetic semiconductor
Cd1−xMnxTe [100] ideal surface is calculated by the semiempirical tight-
binding method in the framework of sps*-model. Surface bands, emerging
above the bulk band structure, as well as their type, energy position and lo-
calization near the parting border with vacuum are investigated. It is shown
that Mn 3d-states as well as sp-states play appreciable role in the formation
of surface bands. The peculiarities of surface band structure are analyzed
in the dependence of solid solution composition.
Key words: diluted magnetic semiconductor, band structure, surface
PACS: 73.20
Semiconductor compound Cd1−xMnxTe represents a solid solution based on two
semiconductors with zinc-blende structure: CdTe and MnTe, in which the part of
nonmagnetic cations is replaced by an element of transition group Mn. The elec-
tronic band structure of semiconductor compounds with magnetic components is
thoroughly studied, both theoretically and experimentally [1–4]. sp-type bands of
such semiconductors show the behaviour similar to sp-bands of the nonmagnetic
material, and magnetic 3d-states of Mn form bands which split up due to strong
coulomb and exchange interactions. The majority of optical and magnetic proper-
ties of diluted magnetic semiconductor (DMS) Cd1−xMnxTe can be explained by the
exchange interaction of sp-band and 3d-states, as well as by Mn-Mn exchange inter-
action, which, in its turn, largely depends on the magnitude of sp-d hybridization
[2].
The majority of recent works on DMS is devoted to the investigation of het-
erostructures (interfaces, superlattices, quantum holes), where one of the compo-
nents is DMS Cd1−xMnxTe [5]. Due to this, the study of the electron band structure
of DMS in the presence of a parting border and particularly the analysis of 3d-states
contribution to the band structure are very important. In the majority of theoreti-
cal approaches a pure atom (ideal) surface is used as a model system for the study
c© S.V.Melnichuk, Y.M.Mikhailevsky, I.M.Rarenko, I.M.Yurijchuk 799
S.V.Melnichuk at al.
of the semiconductor surface electron band structure. In the paper [6] we studied
the energy structure of an [100] ideal surface of semicondutor CdTe, doped by an
isolated transition group impurity. It is shown that in the case when the impurity
substitutes an atom near the surface, essential reconstruction of its energy spectrum
takes place. In the present work the electron band structure of an [100] ideal sur-
face of DMS Cd1−xMnxTe and the contribution of Mn 3d-states to the formation of
surface states are being investigated.
The theoretical approach is based on a semiempirical tight-binding method the
basis of which includes s-, p-orbitals of each atom, cations d-orbitals, and it takes
into account the interaction with the nearest neighbours only [3]. Such a model
gives an opportunity to obtain a realistic band structure over all Brillouin zone of
the crystal that is difficult to achieve in the framework of more complicated first
principles calculations [4] or using the ~k~p-theory [2].
Let’s consider in more detail the electron band structure of a bulk diluted mag-
netic semiconductor. The Hamiltonian of the crystal in the tight-binding method
has the following form:
H = Hsp +Hd +Hsp−d . (1)
Here Hsp is a usual band Hamiltonian of A2B6 group semiconductor where cation
d-orbitals and cation and anion s*-orbitals are added to sp3-basis. The latter take
into account the presence of the excited conduction bands, and make it possible to
describe more correctly the behaviour of the first conduction band [7]. The term Hd
describes intracenter exchange-correlation effects in the half filled 3d-zone, which we
shall treat in the generalized Mott-Hubbard form [8]:
Hd =
∑
iµσ
(
εµniµσ +
U
2
niµσniµ−σ −
J
2
∑
ν 6=µ
niµσniνσ
)
. (2)
Here niµσ is an occupation number of 3d-orbitals of type µ(µ = t2g, eg) with spin σ
on i Mn site. The parameters U and J are responsible for the intracentral Coulomb
as well as exchange interactions, correspondingly. Despite of a manybody nature of
the Hamiltonian (2), the band structure of DMS is well described in the one-electron
approximation. Within the framework of this approximation, half filled Mn 3d-band
is splitted into two subbands, one of which is completely filled and lies in the valence
band. The magnitude of splitting is Ueff = U + 4J [3]. Thus, the ground state of
the system is provided with all five 3d-electrons pointed in one direction and the
full magnetic moment on each site is equal to 5/2. The last term in (1) takes into
account the interaction between 3d-electrons and sp-bands.
The electron spectrum of Cd1−xMnxTe is calculated within virtual crystal ap-
proximation [1]. Matrix elements Hsp for two limiting CdTe and MnTe cases are
expressed through tight-binding parameters [7,9], which were determined by the
adjustment of spectrum in Γ and X points of the Brillouin zone to the known ex-
perimental and theoretical data. If for CdTe such a procedure can be accomplished
directly through the use of experimental data, for hypothetical MnTe with zinc-
blende structure in order to determine the tight-binding parameters we use first
800
Band structure of [100] surface of Cd1−xMnxTe
principles calculations of MnTe ferromagnetic phase [4]. It is necessary to distin-
guish two cases of spin direction on Mn sites: up (↑) and down (↓). The paramag-
netic phase is received under the assumption that up and down spins are distributed
in cation sites of the lattice at random. For parameterizations of the paramagnetic
MnTe Hamiltonian it is necessary to average the tight-binding parameters for two
possible spin directions. Therefore, in the virtual crystal approximation the spec-
trum of paramagnetic Cd1−xMnxTe is simulated by pseudo-ternary solid solution
Cd1−xMn↑x/2Mn↓x/2Te [3].
Figure 1. Electron states density of
CdTe, MnTe and Cd0.5Mn0.5Te semi-
conductors. Dashed lines correspond
to the partial contribution of Mn 3d-
states.
The magnitude of the intracenter effec-
tive splitting Ueff , which determines the po-
sition of the occupied and unoccupied Mn-
states, is crucial for the parameterizations
of the Hamiltonian (2). By the research of
synchrotron radiation and photoemission
spectroscopy in Cd1−xMnxTe it is firmly es-
tablished that the band of the occupied 3d-
states lies at the energy 3.4 eV, below the
edge of the valence band Ev of the semi-
conductor [2,3]. The magnitude of Ev −Ed
= 3.4 eV practically does not depend on
the concentration x. The placement of the
unoccupied 3d-states has evoked the great-
est differences among researchers. How-
ever,the recent study of ultraviolet inverse
photoemission from the conductivity band
in Cd1−xMnxTe has made it possible to
evaluate the magnitude of effective split-
ting in the limits Ueff = 7.0±0.2 eV [9].
Due to this, we can state that the bands
of the unoccupied 3d-states lie in the first
conduction band approximately at the en-
ergy 3.6 eV. Another important parame-
ter of the problem is Vpd, which defines the
magnitude of sp-d hybridization. From general point of view, hybridization parame-
ter must be different for two different spin configurations. The value for the param-
eter of sp-d-hybridization is taken directly from the experimentally measured sp-d
exchange interaction constant. The evaluation gives for Vpd the following value Vpd=
0.219 eV [9]. As far as in the literature there is a unique value for the sp-d hybridiza-
tion parameter, we consider a model in which these parameters are identical. As for
the values of other tight-binding parameters for CdTe and paramagnetic MnTe as
well as their corresponding discussion one can find in [11].
In figure 1 we present the densities of electron states for CdTe, paramagnetic
MnTe and Cd1−xMnxTe with x=0.5, calculated by means of determined tight-
binding parameters. The partial contribution of Mn 3d-states is shown with a dashed
801
S.V.Melnichuk at al.
line. As follows from the figure, there are two peaks lower than the valence band
edge in the energy region 3–4 eV which correspond to the band of the occupied
3d-states, split due to the sp-d hybridization. The bands of unoccupied states give
a maximum somewhat above the bottom of the conduction band. Let’s mark a sig-
nificant contribution of 3d-states to the valence band states in the region 0–2.5 eV.
Our calculations of the electronic band structure of DMS Cd1−xMnxTe coincide, in
general, with theoretical calculations of other authors.
A crystal, limited by an ideal surface, can be represented as a set of crystallo-
graphic planes, parallel to the plane, which forms the boundary of the crystal with
vacuum. For the crystal with zinc-blende structure with an ideal surface perpendic-
ular to the direction [100] each atomic plane contains the atoms of one type (cations
or anions). The coordinate system is selected in a way that the axe OZ is directed
parallel to the direction [100], and the axes OX, OY are directed along the basis vec-
tors of the elementary translations of the two-dimensional lattice. The equilibrium
position of any atom of such a structure is determined by the vector
~R(Nplk) = l1 ~a1 + l2 ~a2 + ~τ
p
⊥ + ~τ
pk
‖ , (3)
where Np – the number of the atomic plane (16 Np < ∞); l1, l2 – integers; ~a1, ~a2
– vectors of the elementary translation of the two-dimensional lattice; the vector
~τ
p
⊥ – indicates the position of the atomic plane Np, relative to the surface, and the
vector ~τ pk‖ – indicates the placement of k-type atom in the atomic plane Np inside
the two-dimensional cell (k = 1,2).
The eigenfunctions of the crystal, limited by [100] surface are characterized by
the vector ~k‖, which lies in the two-dimensional Brillouin zone in the plane, per-
pendicular to the direction [100]. In the framework of the tight-binding model the
crystal wave function is represented as a linear combination of atomic orbitals φα(~R),
centered on the sites (3)
Ψ~k‖a
(~r ) =
∑
αNp
cαNp
(~k‖a)φαNp
(~r ). (4)
Here α runs over cation s-, p-, d-, s*- orbitals and anion s-, p-, s*-orbitals. In the
base (4) the Hamiltonian (1), taking into account (2), gives the secular matrix for
determining the electron spectrum of the crystal with the surface
|HαNp,αN
′
p
(~k‖a)− Eδij | = 0. (5)
The Hamiltonian matrix (5) has got, generally speaking, an infinite dimension.
In numerical calculations the surface is simulated by a slab, i.e. the semi-infinite
crystal, which is limited by the second plane, that is identical to the plane forming
the boundary of the crystal with vacuum [12]. Thus, the system is simulated by
a slab of a finite width, but infinite in the direction, parallel to the surface. Our
calculations showed that it is enough to select a slab consisting of 15–20 atomic
planes. For such a width of the slab, the wave functions of the opposite surfaces are
not overlapped any more and the electron spectrum practically does not depend on
the inclusion of additional planes.
802
Band structure of [100] surface of Cd1−xMnxTe
Figure 2. Electronic band struc-
ture of [100] ideal surface of
DMS Cd0.5Mn0.5Te. In insertion,
two-dimensional Brillouin zone is
presented.
Figure 3. Electron states density
of DMS Cd0.5Mn0.5Te with [100]
ideal surface, projected on the atomic
plane which forms the parting border.
Dashed lines correspond to the partial
contribution of Mn 3d-states.
The band structure of an ideal [100]
surface of DMS Cd1−xMnxTe (x=0.5),
calculated along some high-symmetry di-
rections of the two-dimensional Brillouin
zone, is presented in figure 2. At the for-
mation of the surface, surface bands ap-
pear in the spectrum of the bulk crystal
due to breakdown of the bonds intrinsic
to the crystal. As far as [100] the surface
is polar, it is necessary to distinguish the
two types of the surface, one of which con-
tains cations on the parting border, and the
other contains anions. The surface states
for the two types of the ideal surface are
presented in the same figure and desig-
nated correspondingly as Ci and Ai. We
are interested in the bands which are sit-
uated in the forbidden band gap of the
semiconductor or in the valence band and
the first conduction band. For the anion
surface, the three bands are being marked
A1, A2, A3, one of which – A1 is located in
the forbidden band gap of the semiconduc-
tor, somewhat above the edge of the va-
lence band. The cation surface gives the
two surface bands C1 and C2. In order to
determine the contribution of Mn 3d-states
to the formation of the surface bands of
DMS Cd1−xMnxTe the projections of the
full densities of electron states and partial
contribution of Mn 3d-states on the sur-
face which form the parting border of the
crystal were calculated (figure 3). In the
figure the peaks, which are absent in the
density of states of the bulk crystal, cor-
respond to the surface bands that specify
space localization of the surface bands near
the parting border. As follows from the fig-
ure, although the surface bands are mainly
of sp-character they contain significant ad-
mixture of Mn 3d-states. The degree of lo-
calization of the electron density of the surface bands for a certain value of the
wave vector depends on the position of the wave vector in the Brillouin zone of the
crystal. In figures 4, 5 the dependence of the magnitude of localization for DMS
803
S.V.Melnichuk at al.
Figure 4. Degree of localization of sur-
face states electron density near [100]
Cd0.5Mn0.5Te cation surface for two
points in the Brillouin zone.
Figure 5. The same as in figure 4 but
for the anion surface.
Cd0.5Mn0.5Te on the distance to the surface is presented. As an example, the results
for two high-symmetry points of the Brillouin zone – Γ and X are indicated. As
follows from the figure, the electron densities of surface states Ai, Ci locate mainly
on the planes which lie near the plane forming the parting border of the crystal
with vacuum and practically disappear at the distance of 3–4 nuclear planes from
the surface. The surface states in the band gap of the semiconductor – A1, C1 are
localized in the Brillouin zone for all wave vectors, though in Γ point the localiza-
tion is weaker. As for A2-C2-states which are in resonance with the valence band,
a noticeable localization exhibits only for the wave vectors close to high-symmetry
points of the Brillouin zone. In Γ point they are completely delocalized in the crystal.
Qualitatively the same results for the localization of the surface states take place
for Cd1−xMnxTe solid solutions with the other x.
The contribution of Mn 3d-states to the surface states depends mainly on the
composition of Cd1−xMnxTe solid solution. The relative contribution of 3d-states
to the surface states A1, C1 is presented in the table 1 for various x. The relative
contribution of 3d-states increases with an increase of Mn component in the solution
reaching the value of 20–30 % for x=0.75.
Energies of the surface states for x < 0.5 exhibit linear dependence on the
composition of the solid solution (figure 6). If the dependence of the Cd1−xMnxTe
804
Band structure of [100] surface of Cd1−xMnxTe
Table 1. The relative contribution of 3d−states to the surface states.
concentration Γ X
C1 A1 C1 A1
0.25 0.14 0.08 0.16 0.06
0.50 0.25 0.12 0.22 0.17
0.75 0.31 0.16 0.27 0.26
band gap in Γ point has a form Eg=1.62 + 1.61x, then for the energy dependence
of A1 states in Γ point, the linear coefficient is equal to 0.83, and for A2 states it
is equal to 0.55. Energies of the surface states in the Brillouin zone edges reveal a
much weaker dependence on x.
Figure 6. Dependence of energy of
surface states A1, C1 in Γ point of the
Brillouin zone on solid solution com-
position.
We can conclude that Mn 3d-states give
a noticeable contribution to the formation
of the conduction and valence bands as well
as to the formation of the bands of sur-
face states. The carried out calculations
let us analyze the magnitude of localiza-
tion of electron densities of surface states
and their energy in the dependence of the
solid solution composition. Especially sig-
nificant localization is observed for the sur-
face states with the wave vector close to the
Brillouin zone edges and with an increase
of Mn content in the solid solution. The
study of a model system (an ideal surface)
can serve as a starting-point for the inves-
tigation of more complicated heterostruc-
tures, based on the diluted magnetic semi-
conductor Cd1−xMnxTe.
References
1. Furdyna J.K., Kossut J. Diluted magnetic semiconductors. Moscow, Mir, 1992.
2. Larson B.E., Haas K.C., Ehrenreich H.E., Carlson A.E. Theory of exchange interac-
tions and chemical trends in diluted magnetic semiconductors. // Phys. Rev B, 1988,
vol. 37, p. 4137.
3. Haas K.C., Ehrenreich H. Band structure of semimagnetic compounds. // Acta Phys-
ica polonica, 1988, vol. A73, p. 933.
4. Su-Huai Wei, Zunger A. Total-energy and band structure calculation for the semimag-
netic Cd1−xMnxTe semiconductor alloy and its binary constituents. // Phys. Rev B,
1987, vol. 35, p. 2340.
805
S.V.Melnichuk at al.
5. Young P.M., Ehrenreich H.E. Electronic structure of superlattices incorporating di-
luted magnetic semiconductors. // Phys. Rev B, 1991, vol. 43, p. 2305.
6. Melnychuk S.V., Yurijchuk I.M. Energy spectrum of transition metal impurity in a
semiconductor with an ideal surface. // Cond. Matter Phys., 1999, vol. 2, No. 1(17),
p. 133.
7. Vogl P., Hjalmarson H.P., Dow J.D. A semiempirical tightbinding theory of the elec-
tronic structure of semiconductors. // J. Phys. Chem. Solids., 1983, vol. 44, p. 365.
8. Masek J., Velicky B., Janis V. A tight-binding study of the electronic structure of
MnTe. // J. Phys. C: Solid State Phys., 1987, vol. 20, p. 59.
9. Harrison W. Electron structure and solid state properties. Moscow, Mir, 1983 (in
Russian).
10. Taniguchi M., Mimura K., Sato H., Harada J., Miyazaki M., Namatame H., Ueda Y.
Ultraviolet inverse-fotoemission and fotoemission spectroscopy studies of diluted mag-
netic semiconductors Cd1−xMnxTe (0 6 x 6 0.7). // Phys. Rev B, 1995, vol. 51,
p. 6932.
11. Melnichuk S.V., Mikhailevsky Y.M., Rarenko I.M., Yurijchuk I.M. Surface band spec-
trum of semiconductors of A2B6 group. // The scientific bulletin of Chernivtsy state
university, 1998, vol. 40, Physics, p. 30 (in Ukrainian).
12. Behshtedt F., Enderline R. Surfaces and borders in semiconductors. Moscow, Mir,
1990 (in Russian).
Зонна структура поверхнi [100] напiвмагнiтного
напiвпровiдника Cd1−xMnxTe
С.В.Мельничук, Я.М.Михайлевський, I.М.Раренко,
I.М.Юрiйчук
Чернiвецький державний унiверситет,
вул. Коцюбинського, 6, 58012 Чернiвцi
Отримано 12 грудня 1999 р., в остаточному виглядi –
21 квiтня 2000 р.
Розраховано електронну зонну структуру iдеальної поверхнi [100]
напiвмагнiтного напiвпровiдника Cd 1−x Mn x Te в sps*-моделi силь-
ного зв’язку, що включає катiоннi d -орбiталi. Вивчено зони поверх-
невих станiв, якi виникають на фонi спектра об’ємного кристалу, їх
тип, енергетичне положення та просторову локалiзацiю бiля границь
роздiлу з вакуумом. Показано, що поряд з sp -станами помiтну роль
у формуваннi поверхневих станiв вiдiграють 3d -стани Mn. Аналiзу-
ються особливостi спектра поверхнi залежно вiд складу твердого
розчину.
Ключові слова: напiвмагнiтний напiвпровiдник, зонна структура,
поверхня
PACS: 73.20
806
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