Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen
The results of investigations of dielectric characteristics of GaSe nanocrystals and their hydrogen intercalates are presented. By using the impedance spectroscopy method, it is established that the dielectric spectra of GaSe and HxGaSe (х = 0.07 and 0.14) nanocrystals correspond to the exponent...
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| Опубліковано в: : | Semiconductor Physics Quantum Electronics & Optoelectronics |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2007
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| Цитувати: | Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen / V.M. Kaminskii, Z.D. Kovalyuk, V.V. Netyaga, and V.B. Boledzyuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 84-86. — Бібліогр.: 11 назв. — англ. |
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Kaminskii, V.I. Kovalyuk, Z.D. Netyaga, V.V. Boledzyuk, V.B. 2017-05-28T18:02:01Z 2017-05-28T18:02:01Z 2007 Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen / V.M. Kaminskii, Z.D. Kovalyuk, V.V. Netyaga, and V.B. Boledzyuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 84-86. — Бібліогр.: 11 назв. — англ. 1560-8034 PACS 61.46.-Df, 71.20.-Tx, 81.40.-Tv https://nasplib.isofts.kiev.ua/handle/123456789/118130 The results of investigations of dielectric characteristics of GaSe nanocrystals and their hydrogen intercalates are presented. By using the impedance spectroscopy method, it is established that the dielectric spectra of GaSe and HxGaSe (х = 0.07 and 0.14) nanocrystals correspond to the exponent law of dielectric response. It is found that there is an increase of the dielectric constant ε∞ for the intercalated samples in comparison with that of the initial sample. We have obtained the frequency dependences of the real and imaginary parts of the conductivity, whose dispersion is due to the presence of two-dimensional defects. Equivalent electrical circuits which determine electrical characteristics of the crystals under study are proposed. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen Article published earlier |
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| title |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen |
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Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen Kaminskii, V.I. Kovalyuk, Z.D. Netyaga, V.V. Boledzyuk, V.B. |
| title_short |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen |
| title_full |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen |
| title_fullStr |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen |
| title_full_unstemmed |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen |
| title_sort |
dielectric characteristics of gase nanocrystals intercalated with hydrogen |
| author |
Kaminskii, V.I. Kovalyuk, Z.D. Netyaga, V.V. Boledzyuk, V.B. |
| author_facet |
Kaminskii, V.I. Kovalyuk, Z.D. Netyaga, V.V. Boledzyuk, V.B. |
| publishDate |
2007 |
| language |
English |
| container_title |
Semiconductor Physics Quantum Electronics & Optoelectronics |
| publisher |
Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| format |
Article |
| description |
The results of investigations of dielectric characteristics of GaSe nanocrystals
and their hydrogen intercalates are presented. By using the impedance spectroscopy
method, it is established that the dielectric spectra of GaSe and HxGaSe (х = 0.07 and
0.14) nanocrystals correspond to the exponent law of dielectric response. It is found that
there is an increase of the dielectric constant ε∞ for the intercalated samples in
comparison with that of the initial sample. We have obtained the frequency dependences
of the real and imaginary parts of the conductivity, whose dispersion is due to the
presence of two-dimensional defects. Equivalent electrical circuits which determine
electrical characteristics of the crystals under study are proposed.
|
| issn |
1560-8034 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/118130 |
| citation_txt |
Dielectric characteristics of GaSe nanocrystals intercalated with hydrogen / V.M. Kaminskii, Z.D. Kovalyuk, V.V. Netyaga, and V.B. Boledzyuk // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2007. — Т. 10, № 3. — С. 84-86. — Бібліогр.: 11 назв. — англ. |
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AT kaminskiivi dielectriccharacteristicsofgasenanocrystalsintercalatedwithhydrogen AT kovalyukzd dielectriccharacteristicsofgasenanocrystalsintercalatedwithhydrogen AT netyagavv dielectriccharacteristicsofgasenanocrystalsintercalatedwithhydrogen AT boledzyukvb dielectriccharacteristicsofgasenanocrystalsintercalatedwithhydrogen |
| first_indexed |
2025-11-24T16:25:17Z |
| last_indexed |
2025-11-24T16:25:17Z |
| _version_ |
1850482369578926080 |
| fulltext |
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 84-86.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
84
PACS 61.46.-Df, 71.20.-Tx, 81.40.-Tv
Dielectric characteristics of GaSe nanocrystals
intercalated with hydrogen
V.M. Kaminskii, Z.D. Kovalyuk, V.V. Netyaga, and V.B. Boledzyuk
I.M. Frantsevich Institute for Problems of Materials Science, NAS of Ukraine, Chernivtsi Department
5, Iryna Vilde str., 58001 Chernivtsi, Ukraine; e-mail: chimsp@ukrpost.ua
Abstract. The results of investigations of dielectric characteristics of GaSe nanocrystals
and their hydrogen intercalates are presented. By using the impedance spectroscopy
method, it is established that the dielectric spectra of GaSe and HxGaSe (х = 0.07 and
0.14) nanocrystals correspond to the exponent law of dielectric response. It is found that
there is an increase of the dielectric constant ε∞ for the intercalated samples in
comparison with that of the initial sample. We have obtained the frequency dependences
of the real and imaginary parts of the conductivity, whose dispersion is due to the
presence of two-dimensional defects. Equivalent electrical circuits which determine
electrical characteristics of the crystals under study are proposed.
Keywords: gallium selenide, nanocrystal, intercalation, impedance spectroscopy, dielec-
tric characteristics.
Manuscript received 15.09.07; accepted for publication 27.09.07; published online 30.11.07.
1. Introduction
The anisotropy of physical properties of layered III-VI
semiconductors is caused by peculiarities of their crystal
structure and can be essentially increased when they are
in a form of nanocrystals, as well as due to topochemical
reactions of intercalation (the insertion of foreign atoms
into the interlayer spaces). The insertion of hydrogen
into the lattice of layered materials makes it possible to
apply intercalation systems for the preparation of
hydrogen-containing materials with high hydrogen
content, hydrogen sensors, and solid electrolytes with
high proton conductivity [1, 2].
Earlier, the electrical and optical properties of
hydrogen-containing GaSe and InSe crystals were
investigated in [3-5]. In this work, we present the result
of investigations of dielectric characteristics of GaSe
nanocrystals intercalated with hydrogen.
2. Experimental
Single crystals of GaSe were grown by the Bridgman
method from a stoichiometric melt. By using the
Weissenberg method, it is found that the grown GaSe
crystals belong to the ε-modification (space group 1
3hD ).
Nanopowders of GaSe were obtained by means of the
ultrasonic treatment of micron-sized powders (a grain
dimension of about 75 µm) in a liquid medium (acetone
or ethyl alcohol) under cavitation conditions. From the
X-ray data, it is established that the average dimensions
of the obtained nanoparticles are 70 to 75 nm along the
crystallographic direction [001] [6]. The obtained nano-
particles were pressed at a pressure of 107 Pa into disks
of 9 mm in diameter and 2.3 mm in thickness destined
for further investigations.
Intercalation of GaSe nanopowders with hydrogen
has been carried out by the method of “drawing”
electrical field from a 0.1 N aqueous solution of HCl at
potentials that are below the potential of hydrogen
reduction from this solution (ϕ = 0.36 V with respect to
AgCl electrode). The density of inserted protons was
determined from the amount of charge carried out
through an intercalation cell by measuring the current
density and the intercalation time [7].
Room-temperature impedance spectra were
measured by means of an impedance spectrometer
“Solartron 1255” in the frequency range 0.1 to 106 Hz at
an applied signal of 100 mV.
3. Results and discussion
Figure 1 shows the measured frequency dependences of
complex capacitance С* = C′ − jС′′ for nanocrystalline
samples of GaSe, Н0.07GaSe, and H0.14GaSe. It was
established in [8] that the dielectric spectrum of low-
resistance GaSe single crystals correspond to the
universal exponential law
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 84-86.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
85
10-1 100 101 102 103 104 105
1E-12
1E-11
1E-10
1E-9
1E-8
1E-7
C/ ,C
// , F
f, Hz
C/ (GaSe)
C/ (H
0,07
GaSe)
C/ (H
0,14
GaSe)
C// (GaSe)
C// (H
0,07
GaSe)
C// (H
0,14
GaSe)
Fig. 1. Dielectric spectra expressed in the form of complex
capacitance for nanocrystals of GaSe, H0.07GaSe, and
H0.14GaSe.
( ) 11*
2
cos
2
sin −−
−== nn njnBjBC ωππω ,
where 0 < n < 1 and B is a constant.
As one can see from the presented data for GaSe,
H0.07GaSe, and H0.14GaSe nanocrystals under investiga-
tions (Fig. 1), the frequency dependences of С′ and С′′
can be also described by the exponential law at 0 <
n < 1. For the С′(ν) dependences in the high-frequency
spectral range, there are linear parts with the slope angle
tangent equal to zero, the linear cuts off of which at the
ordinate axis correspond to the high-frequency
capacitance С′∞. Using the obtained С′∞ values, we have
established the comparative increase of the high-
frequency permittivity ε∞ for the intercalated samples in
comparison with that of the initial GaSe sample which is
equal to 1.02 and 1.51 for the H0.07GaSe and H0.14GaSe
samples, respectively. This takes place because of
changes in the polarization processes in the intercalated
materials. At low frequencies, the С′′(ν) dependences
have the linear parts with the slope angle tangent equal
to −1 what is due to the dc conductivity of the samples.
Figure 2 shows the Nyquist plots for the
investigated nanomaterials. The presence of deformed
semicircles in the high-frequency range (curves 2
and 3) is their peculiarity for the intercalated H0.07GaSe
and H0.14GaSe samples. From the obtained data, we
have established the electrical equivalent circuits of the
investigated samples (Fig. 2, inserts b and c) and the
parameters of their elements (Table). Here, СРЕ1 and
СРЕ2 are constant phase elements being used in
equivalent circuits. This allows us to describe the
deformed semicircles at the Nyquist plots (Fig. 2,
curves 2 and 3) for the samples under investigation.
The parameters Y1 and Y2, as well as n1 and n2,
determine numerical values and the behavior type
(resistive or capacitive) of the СРЕ1 and СРЕ2
elements, respectively. The parameter Cδ is the
geometrical capacitance of the investigated sample. As
follows from the listed data, the effective capacitance
Y1 of the СРЕ1 element for the H0.14GaSe sample is
increased by several orders of magnitude in comparison
with that of Н0.07GaSe, and simultaneously the
resistance Rр becomes essentially decreased (by
108 times). On the contrary, the parameter Y2 decreases
with increase in the density of inserted hydrogen. This
indicates that the circuit (СРЕ1 (Rр−СРЕ2)) determines
the “bulk” electrical properties of porous nanopow-
dered НхGaSe samples.
The availability of a weak van der Waals bonding
between the layers of GaSe and a strong ionic-covalent
bonding within them foreordains the possibility of the
insertion of protons into tetrahedral and octahedral sites
of the interlayer spaces. According to the law of
hexagonal close packing [9], one octahedral and two
tetrahedral empty sites correspond to each atom of Se.
Additionally, as distinct from GaSe single crystals, the
intercalated samples can localize hydrogen in pores.
0 1x107 2x107 3x107 4x107
0,0
-5,0x106
-1,0x107
-1,5x107
-2,0x107
1 Hz
1*106 Hz
100 Hz
0,15 Hz
400 Hz
2 kHz
3
2
1
Im
Z
, Ω
Re Z, Ω
CPE1
Rp CPE2
R1
R2
C
b a
Fig. 2. Nyquist plots for samples of GaSe, H0.07GaSe, and
H0.14GaSe (curves 1 to 3, respectively) and equivalent circuits
for the initial GaSe (insert a) and its intercalates (insert b).
Table. Parameters of equivalent circuits for nanocrystalline GaSe samples and their hydrogen intercalates.
Samples
СРЕ1 СРЕ2
Y1,
cm·s0.5/cm2
n1
Rр,
Ohm·сm2
Y2,
Сm·s0.5/сm2
n2
R1,
Ohm·сm2
Сδ,
F/сm2
R2,
Ohm·сm2
GaSe − − − − − 2.4⋅10 5 9.3⋅10 −12 1.6⋅10 8
H0.07GaSe 3.52⋅10−11 0.92 6.1⋅106 4.49⋅10−8 0.21 − − −
H0.14GaSe 2.4⋅10−8 0.05 0.16 2.95⋅10 −11 0.9 − − −
2.0
1.5
1.0
5.0
0.0
0.15
Semiconductor Physics, Quantum Electronics & Optoelectronics, 2007. V. 10, N 3. P. 84-86.
© 2007, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
86
10-1 100 101 102 103 104 105 106 107
10-10
10-9
10-8
10-7
10-6
10-5
10-4
a3
2
1σ/
f, Hz
10-1 100 101 102 103 104 105 106 107 108
10-11
10-10
10-9
10-8
10-7
10-6
10-5
10-4
b
3
2
1
σ//
f, Hz
Fig. 3. Frequency dependences of the real σ′ (a) and imaginary
σ″ (b) parts of the conductivity of GaSe, H0.07GaSe, and
H0.14GaSe nanocrystals (curves 1 to 3, respectively).
The low-frequency linear part for Н0.14GaSe
(Fig. 2, curve 3), which most likely defines the electrical
properties of hydrogen inserted into pores, is a result of
the formation of a space charge nearby the contact
electrodes due to the migration of protons of the
adsorbed electrolyte to the electrodes. As the relaxation
of the processes of ion migration takes place over a long
period of time, it prevails in the low-frequency
impedance. For the intercalated Н0.07GaSe and H0.14GaSe
samples, the obtained values of the relaxation time τ are
4⋅10−4 and 2.6⋅10−4 s, respectively.
Figure 3a, b shows the frequency dependences, σ′(ν)
and σ′′(ν), of the real and imaginary parts of the
conductivity of the initial and intercalated nanocrystalline
samples of GaSe (curves 1-3) (ν is the linear frequency).
The increase of σ′ and σ′′ with frequency can be supposed
to be due to two-dimensional defects (stacking faults)
creating the potential barriers, which can lead to the
dependence of the conductivity on frequency [10, 11]. The
nonlinear behavior of σ′(ν) and σ′′(ν) is probably caused by
the influence of intergrain boundaries on the processes of
charge transfer in the pressed nanocrystalline GaSe
samples. The decrease of the real and imaginary parts of the
conductivity of the intercalated samples is due to a decrease
of the carrier mobility because of a deformation of the
nanostructures. During the intercalation, the inserted ions
deform the GaSe lattice, which follows from the X-ray
investigations on broadening the rocking curves for
reflection (004) obtained in the scheme of two-crystal
spectrometer.
4. Conclusion
It is established that the dielectric spectra of the
nanocrystalline samples of GaSe, Н0.07GaSe, and
H0.14GaSe correspond to the exponential law of dielectric
response. From the carried out measurements of the
impedance, we have constructed equivalent circuits which
determine electrical characteristics of the investigated
crystals, and the increase of the permittivity ε∞ for the
intercalated samples in comparison with that of the initial
GaSe ones is found. We have obtained also the frequency
dependences of the real and imaginary parts of the
conductivity, whose dispersion is due to the presence of
two-dimensional defects.
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