Structure and electrical properties of In₂Se₃Mn layered crystals
Investigations of the crystalline structure and electrical properties of In₂Se₃ 1 wt. %Mn and In₂Se₃ 6 wt. % Mn crystals have been carried out. We have found formation of a substitutional solid solution for In₂Se₃ 1 wt. %Mn single crystals as well as existence of two phases (In₂Se₃ and MnIn₂Se...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2009
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| Назва видання: | Semiconductor Physics Quantum Electronics & Optoelectronics |
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| Цитувати: | Structure and electrical properties of In₂Se₃Mn layered crystals / V.M. Kaminskii, Z.D. Kovalyuk, A.V. Zaslonkin, and V.I. Ivanov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 290-293. — Бібліогр.: 11 назв. — англ. |
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irk-123456789-1188782017-06-01T03:06:09Z Structure and electrical properties of In₂Se₃Mn layered crystals Kaminskii, V.M. Kovalyuk, Z.D. Zaslonkin, A.V. Ivanov, V.I. Investigations of the crystalline structure and electrical properties of In₂Se₃ 1 wt. %Mn and In₂Se₃ 6 wt. % Mn crystals have been carried out. We have found formation of a substitutional solid solution for In₂Se₃ 1 wt. %Mn single crystals as well as existence of two phases (In₂Se₃ and MnIn₂Se₄) in polycrystalline ingots In₂Se₃ 6 wt. % Mn. Temperature dependences of the conductivities across (σ⊥C) and along (σ||C) the crystallographic c axis were measured in the range of 80 to 400 K. From the anisotropy σ⊥C/σ||C of conductivity temperature dependences of the energy barrier value ΔЕδ between the layers were calculated for the crystals under investigations. 2009 Article Structure and electrical properties of In₂Se₃Mn layered crystals / V.M. Kaminskii, Z.D. Kovalyuk, A.V. Zaslonkin, and V.I. Ivanov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 290-293. — Бібліогр.: 11 назв. — англ. 1560-8034 PACS 72.20.Dp, 72.20.-i, 81.10.Fq http://dspace.nbuv.gov.ua/handle/123456789/118878 en Semiconductor Physics Quantum Electronics & Optoelectronics Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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English |
| description |
Investigations of the crystalline structure and electrical properties of
In₂Se₃ 1 wt. %Mn and In₂Se₃ 6 wt. % Mn crystals have been carried out. We have
found formation of a substitutional solid solution for In₂Se₃ 1 wt. %Mn single crystals as
well as existence of two phases (In₂Se₃ and MnIn₂Se₄) in polycrystalline ingots
In₂Se₃ 6 wt. % Mn. Temperature dependences of the conductivities across (σ⊥C) and along
(σ||C) the crystallographic c axis were measured in the range of 80 to 400 K. From the
anisotropy σ⊥C/σ||C of conductivity temperature dependences of the energy barrier value
ΔЕδ between the layers were calculated for the crystals under investigations. |
| format |
Article |
| author |
Kaminskii, V.M. Kovalyuk, Z.D. Zaslonkin, A.V. Ivanov, V.I. |
| spellingShingle |
Kaminskii, V.M. Kovalyuk, Z.D. Zaslonkin, A.V. Ivanov, V.I. Structure and electrical properties of In₂Se₃Mn layered crystals Semiconductor Physics Quantum Electronics & Optoelectronics |
| author_facet |
Kaminskii, V.M. Kovalyuk, Z.D. Zaslonkin, A.V. Ivanov, V.I. |
| author_sort |
Kaminskii, V.M. |
| title |
Structure and electrical properties of In₂Se₃Mn layered crystals |
| title_short |
Structure and electrical properties of In₂Se₃Mn layered crystals |
| title_full |
Structure and electrical properties of In₂Se₃Mn layered crystals |
| title_fullStr |
Structure and electrical properties of In₂Se₃Mn layered crystals |
| title_full_unstemmed |
Structure and electrical properties of In₂Se₃Mn layered crystals |
| title_sort |
structure and electrical properties of in₂se₃mn layered crystals |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| publishDate |
2009 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/118878 |
| citation_txt |
Structure and electrical properties of In₂Se₃Mn layered crystals / V.M. Kaminskii, Z.D. Kovalyuk, A.V. Zaslonkin, and V.I. Ivanov // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2009. — Т. 12, № 3. — С. 290-293. — Бібліогр.: 11 назв. — англ. |
| series |
Semiconductor Physics Quantum Electronics & Optoelectronics |
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AT kaminskiivm structureandelectricalpropertiesofin2se3mnlayeredcrystals AT kovalyukzd structureandelectricalpropertiesofin2se3mnlayeredcrystals AT zaslonkinav structureandelectricalpropertiesofin2se3mnlayeredcrystals AT ivanovvi structureandelectricalpropertiesofin2se3mnlayeredcrystals |
| first_indexed |
2025-07-08T14:49:31Z |
| last_indexed |
2025-07-08T14:49:31Z |
| _version_ |
1837090652874080256 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 290-293.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
290
PACS 72.20.Dp, 72.20.-i, 81.10.Fq
Structure and electrical properties of In2Se3Mn layered crystals
V.M. Kaminskii, Z.D. Kovalyuk, A.V. Zaslonkin, and V.I. Ivanov
I.M. Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, Chernivtsi Department
5, Iryna Vilde str., 58001 Chernivtsi, Ukraine,
Phone: (0372)52-51-55, fax (03722) 3-60-18: e-mail: chimsp@ukrpost.ua
Abstract. Investigations of the crystalline structure and electrical properties of
In2Se31 wt. %Mn and In2Se36 wt. % Mn crystals have been carried out. We have
found formation of a substitutional solid solution for In2Se31 % Mn single crystals as
well as existence of two phases (In2Se3 and MnIn2Se4) in polycrystalline ingots
In2Se36 % Mn. Temperature dependences of the conductivities across (σC) and along
(σ||C) the crystallographic c axis were measured in the range of 80 to 400 K. From the
anisotropy σC/σ||C of conductivity temperature dependences of the energy barrier value
ΔЕδ between the layers were calculated for the crystals under investigations.
Keywords: indium selenide, layered crystal, X-ray diffraction, substitutional solid
solution, conductivity.
Manuscript received 26.01.09; revised manuscript received 13.03.09, accepted for
publication 14.05.09; published online 30.06.09.
1. Introduction
In2Se3 compound belongs to the group of semiconductor
materials with a layered crystal structure. In2Se3 single
crystals can be used for fabrication of ionizing radiation
detectors, solid-state electrodes, photosensitive
heterostructures. It is known that α-, β-, and γ- phases of
In2Se3 exist [1], and the phase transition α → β takes
place at the temperature 200 С, while β → γ occurs at
650 С. According to [1], the α-In2Se3 phase has a
hexagonal structure with the unit cell parameters a = 4.0
and с = 19.24 Å, whereas in [2] it was found that the
structure of the phase is trigonal (the R3mH spatial
group) with а = 4.05 and с = 28.77 Å.
Electrical properties of crystalline In2Se3 differ
essentially, which is related to the technique of growing
the crystals [1, 3, 4]. In particular, in [4] investigations
of the electrical properties of In2Se3 single crystals
doped with Cd, I, and Cu were carried out to have
crystals with a wide spectrum of physical properties and
suitable for application in optoelectronics. As to
behaviour of Mn, as a magnetic dopant, in layered
crystals, note that doping the InSe single crystals with
manganese results in appearance of ferromagnetic
interaction between Mn ions [5].
In this work, we present the investigations of the
crystalline structure and electrical properties of In2Se3
crystals doped with Mn aimed to receive materials
suitable for application in spintronics at room
temperature.
2. Experimental
The doped In2Se3Mn single crystals were grown by the
Bridgman method from stoichiometric melts in silica
ampoules of 12 mm in diameter. Doping with
manganese was carried out adding the dopant in the
amounts 1 and 6 wt. % to the charge before synthesis of
the compound. The rate of the growth of the ingots was
1 mm/h at the temperature gradient at the crystallization
front of 15 С/сm. Determination of the crystal structure
of the grown single crystals was performed by using a
DRON-3 installation in CuKα-radiation. The obtained X-
ray diffraction patterns have been analyzed by using a
LATTIK-KARTA software. The Mn content and its
distribution along the grown In2Se36 % Mn single
crystal was determined by the X-ray fluorescence
analysis by means of a TRACOR installation.
Electrical properties of In2Se31 % Mn and
In2Se36 % Mn were measured in the temperature range
80 to 400 K. The samples for conductivity
measurements along the layers σC had dimensions
11×2.5×0.75 mm with the conventional geometry of six
contacts deposited by soldering with high purity indium.
The measurements of the conductivity across the layers
σ||C were carried out by using a four-probe method with
the contacts located at the opposite sides of the samples:
two of them covered almost the whole cleavage surfaces
and were used as current contacts, and two others close
to them small-area contacts − as the probe ones.
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 290-293.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
291
3. Results and discussions
Fig. 1a, b shows the X-ray diffraction patterns of
In2Se31 % Mn and In2Se36 % Mn crystals registered
from cleavage surfaces of the both ingots. For the
In2Se31 % Mn single crystal the X-ray diffraction
pattern (Fig. 1a) shows the reflections 00l (l = 6, 9, 12,
15, 18). The presence of an additional peak at 2θ = 26.5°
is an evidence of the presence of selenium
microinclusions. The measured parameters of the unit
cell of the In2Se31 % Mn single crystal are а =
4.000 0.003 and с = 28.330 0.009 Å, which is some
less than the lattice parameters for undoped In2Se3 [2].
So, one can assume the formation of In2Se31 % Mn
substitutional solid solution because of the substitution
of In atoms with those of Mn much less in size (the
atomic radii of 1.63 and 1.37 Å, respectively [6]).
Fig. 1b shows the registered hkl reflections for
In2Se36 % Mn, which indicates polycrystalline structure
of the grown crystal. From the carried out indexing of the
X-ray diffraction pattern in Fig. 1b, we have found the
existence of two phases in the grown ingot: α-In2Se3 and
MnIn2Se4 of the trigonal structure (R3mH spatial group).
The calculated interlayer distances dcalc determined on the
basis of the α-In2Se3 and MnIn2Se4 lattice parameters
[2, 7] as well as the experimental ones dexp obtained from
Fig. 1b are listed in Table. The measured values of the
lattice parameters for α-In2Se3 (а = 4.025 and с =
28.771 Å) and MnIn2Se4 (а = 4.052 and с = 39.420 Å) are
in good agreement to the data of [2, 7]. From our analysis
of the intensities of all the registered reflections from α-
In2Se3 and MnIn2Se4, it is determined that the content of
these phases is 53.26 and 46.74 %, respectively. The
carried out X-ray fluorescence analysis of the distribution
of Mn impurity has shown that the content of Mn in the
crystal In2Se36 % Mn increases monotonously from
0.83 at. % at the beginning of the ingot to 2 at. % near its
end. The total amount of the dopant in the ingot was
determined as 1.174 at. %. The presence of excess indium
in the studied crystals was not found.
It is necessary to note that at the formation of
MnIn2Se4 the next reaction 3Mn + 4In2Se3 =
3In2MnSe4 + 2In should take place between the initial
components. We have carried out calculations and
plotted dependences of weight content of the solid
phases In2Se3, MnIn2Se4, and In on the amount of
reacted Mn (in the range 0-8 %). It was ascertained that
due to interaction between 4 % Mn and 96 % In2Se3, the
mixture of In2Se3 (51 %), MnIn2Se4 (44 %), and In (5 %)
was created. These data are in agreement to the results of
X-ray structure and fluorescence analysis. One can
assume that not reacted Mn and segregated In are
rejected to the end of the ingot during growing the
crystal. After interaction of 6 % Mn and 94 % In2Se3, the
content of solid phases is as follows: 26.07 % In2Se3,
65.57 % MnIn2Se4, and 8.36 % In.
Тable. The experimental dexp and calculated dcalc values of
the interlayer distances diffraction peaks for In2Se3 and
MnIn2Se4.
In2Se3 MnIn2Se4
hkl dcalc, Å dexp, Å hkl dcalc, Å dexp, Å
003 9.591 9.586 006 6.577 6.567
006 4.795 4.787 009 4.385 4.370
009 3.197 3.192 012 3.454 3.454
104 3.151 3.135 104 3.306 3.301
107 2.668 2.659 00.12 3.289 3.281
00.12 2.398 2.397 015 3.206 3.204
10.10 2.224 2.220 107 2.979 2.975
01.11 2.097 2.093 018 2.859 2.857
110 2.020 2.025 00.15 2.631 2.630
113 1.981 1.970 01.11 2.508 2.504
00.15 1.918 1.919 10.13 2.296 2.295
10.13 1.872 1.870 01.14 2.197 2.196
116 1.865 1.858 116 1.936 1.936
00.18 1.598 1.598 00.21 1.879 1.877
00.24 1.6443 1.6438
11.15 1.6050 1.6055
a
b
Fig. 1. X-ray diffraction patterns of In2Se31 wt. % Mn (а) and
In2Se36 wt. % Mn (b) crystals in Cu-Kα- radiation. Diffraction
lines of In2Se3 are marked as ↓ and those of MnIn2Se4 – as ↑.
The temperature dependences of the conductivity
along (σ||C) and across (σC) the crystallographic c axis of
In2Se3, In2Se31 % Mn, and In2Se36 % Mn samples are
shown in Fig. 2a, b. It is necessary to note that the
undoped In2Se3 sample has n-type conductivity with the
free electron concentration n = 4.9∙1017 cm-3 and the Hall
electron mobility along the layers μC = 405 cm2/V∙s at
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 290-293.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
292
a
b
Fig. 2. The temperature dependences of conductivities σ||C (а)
and σC (b) for In2Se3, In2Se31 wt. % Mn, and
In2Se36 wt. % Mn crystals.
room temperature. The values of the conductivity
components are σ||C = 0.7 and σC = 32 Ohm-1сm-1 at Т =
300 K. As follows from Fig. 2a, b, the temperature
dependences of the σ||C and σC components differ
essentially and demonstrate semiconductor and “metallic”
character, which is caused by a distinction in the charge
transport mechanisms in the different crystallographic
directions. It is possible to suppose that the semiconductor
character of σ||C(T) is related to a preferable increase of the
electron concentration n, whereas the metallic character of
σC(T) is caused by a prevailing decrease of the mobility
μC(T) over the increase of n. The observed decrease of
σ||C and σC values for the In2Se31 % Mn sample in the
whole temperature range can be explained by a decrease
of the mobility due to scattering of carriers on spatial
inhomogeneities caused by formation of substitutional
solid solution and the presence of selenium
microinclusions.
For the two-phase polycrystalline sample of
In2Se36 % Mn, we have found that the conductivities
σ||C and σC are increased nearly by two orders of
magnitude over the whole temperature range in
comparison to that with 1 wt. % of manganese. One can
suppose that in this case the conductivity mechanism has
a complex character and is caused by the presence of
In2Se3 and MnIn2Se4 grains as well as by possible
influence of the intercrystallite boundaries on the charge
transport processes. As the resistivity of the MnIn2Se4
phase is higher than that for In2Se3 [8], the increase of
the conductivity components σ||C and σC for
In2Se36 % Mn in comparison to In2Se3 can be
considered as caused by an increase of different type
defects, the aggregation of which creates drain channels
for trapped charge. A generalized barrier model predicts
both an increase and decrease of the resistivity of
polycrystalline samples in comparison to single
crystals [9].
The temperature dependences of the conductivity
anisotropy for In2Se31 % Mn and In2Se36 % Mn
samples (Fig. 3) show the increase of σC/σ||C with
decreasing temperature over the whole temperature
range. In comparison to the data from [4] for undoped
In2Se3 (the anisotropy ratio is 660 and 450 at 80 and
300 K, respectively), there is an increase of the
conductivity anisotropy due to doping with Mn.
High values of the conductivity anisotropy in
layered crystals are caused by peculiarities of the energy
bands forming the edge of fundamental absorption [10]
as well as by the influence of structural defects on
charge transport processes. The presence of weak Van
der Waals coupling between the layers promotes
localization of impurities in octahedral and tetrahedral
sites in the interlayer spaces and also the formation of
stacking faults. The planar structure defects form
additional energy barriers ΔЕδ for the transport of charge
carriers along the crystallographic c axis. In this case,
according to [11] the anisotropy ratio can be written as
kT
E
exp
σ
σ
||C
C . (1)
Fig. 3. Temperature dependences of the conductivity anisotropy
σC /σ||C for In2Se31 wt. % Mn and In2Se36 wt. % Mn crystals.
Here, k is the Boltzmann constant. To determine
the magnitude of this barrier, the conductivity anisotropy
temperature dependences were plotted in the coordinates
of Arrhenius (ln(σC/σ||C) vs 103/Т). From the slopes in
the low temperature range, we have found that ΔЕδ is
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2009. V. 12, N 3. P. 290-293.
© 2009, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
293
equal to 5.5 and 18 meV for the In2Se31 % Mn and
In2Se36 % Mn samples, respectively.
4. Conclusions
From the X-ray investigations, we have established the
formation of a substitutional solid solution in
In2Se31 % Mn single crystals as well as the existence
of two phases In2Se3 (53.26 %) and MnIn2Se4 (46.74 %)
in polycrystalline In2Se36 % Mn ingots.
The obtained temperature dependences of the
conductivity components σ||C and σC have
semiconductor and “metallic” behaviour, respectively,
and their values increase with increasing the dopant
content.
The high values of the conductivity anisotropy
σC/σ||C are caused by the presence of structural defects
localized in the interlayer space of the crystals. The
energy barrier value ΔЕδ between the layers estimated
from the σC/σ||C temperature dependences in the low
temperature range is equal to 5.5 and 18 meV for
In2Se31 % Mn and In2Se36 % Mn crystals,
respectively.
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