Conductivity of the Bi₁₂SiO₂₀ thin films
The results of the conductivity examination in the Bi₁₂SiO₂₀ thin films prepared using the sol-gel method are presented. The conductivity was investigated in the 300–550 K temperature and up to 100 V/cm field ranges. It was observed that the charge carrier transfer at the flow level, situated in the...
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Інститут фізики конденсованих систем НАН України
1999
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| Zitieren: | Conductivity of the Bi₁₂SiO₂₀ thin films / S.N. Plyaka, G.Ch. Sokolyanskii, E.O. Klebanskii, L.Ja. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 625-630. — Бібліогр.: 6 назв. — англ. |
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irk-123456789-1205882017-06-13T03:03:02Z Conductivity of the Bi₁₂SiO₂₀ thin films Plyaka, S.N. Sokolyanskii, G.Ch. Klebanskii, E.O. Sadovskaya, L.Ja. The results of the conductivity examination in the Bi₁₂SiO₂₀ thin films prepared using the sol-gel method are presented. The conductivity was investigated in the 300–550 K temperature and up to 100 V/cm field ranges. It was observed that the charge carrier transfer at the flow level, situated in the tail of the density of states into the forbidden band is dominant for the investigated sample at T > 500 K. The obtained results are explained in terms of the highly compensated doped semiconductor model. Тонкi плiвки сiленiту вiсмуту були отриманi золь-гель методом. У широкому діапазонi полів та температур були дослiдженi вольт-ампернi характеристики та електропровiднiсть. Знайдено, що перенесення носiїв заряду в тонких плiвках при T > 500 K здiйснюється по рiвню протiкання, розташованому у хвостi густини локалiзованих станiв. Отриманi результати обговорюються у рамках моделi легованих компенсованих напiвпровiдникiв. 1999 Article Conductivity of the Bi₁₂SiO₂₀ thin films / S.N. Plyaka, G.Ch. Sokolyanskii, E.O. Klebanskii, L.Ja. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 625-630. — Бібліогр.: 6 назв. — англ. 1607-324X DOI:10.5488/CMP.2.4.625 PACS: 73.61 http://dspace.nbuv.gov.ua/handle/123456789/120588 en Condensed Matter Physics Інститут фізики конденсованих систем НАН України |
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The results of the conductivity examination in the Bi₁₂SiO₂₀ thin films prepared using the sol-gel method are presented. The conductivity was investigated in the 300–550 K temperature and up to 100 V/cm field ranges. It
was observed that the charge carrier transfer at the flow level, situated in
the tail of the density of states into the forbidden band is dominant for the
investigated sample at T > 500 K. The obtained results are explained in
terms of the highly compensated doped semiconductor model. |
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Article |
| author |
Plyaka, S.N. Sokolyanskii, G.Ch. Klebanskii, E.O. Sadovskaya, L.Ja. |
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Plyaka, S.N. Sokolyanskii, G.Ch. Klebanskii, E.O. Sadovskaya, L.Ja. Conductivity of the Bi₁₂SiO₂₀ thin films Condensed Matter Physics |
| author_facet |
Plyaka, S.N. Sokolyanskii, G.Ch. Klebanskii, E.O. Sadovskaya, L.Ja. |
| author_sort |
Plyaka, S.N. |
| title |
Conductivity of the Bi₁₂SiO₂₀ thin films |
| title_short |
Conductivity of the Bi₁₂SiO₂₀ thin films |
| title_full |
Conductivity of the Bi₁₂SiO₂₀ thin films |
| title_fullStr |
Conductivity of the Bi₁₂SiO₂₀ thin films |
| title_full_unstemmed |
Conductivity of the Bi₁₂SiO₂₀ thin films |
| title_sort |
conductivity of the bi₁₂sio₂₀ thin films |
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Інститут фізики конденсованих систем НАН України |
| publishDate |
1999 |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/120588 |
| citation_txt |
Conductivity of the Bi₁₂SiO₂₀ thin films / S.N. Plyaka, G.Ch. Sokolyanskii, E.O. Klebanskii, L.Ja. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 625-630. — Бібліогр.: 6 назв. — англ. |
| series |
Condensed Matter Physics |
| work_keys_str_mv |
AT plyakasn conductivityofthebi12sio20thinfilms AT sokolyanskiigch conductivityofthebi12sio20thinfilms AT klebanskiieo conductivityofthebi12sio20thinfilms AT sadovskayalja conductivityofthebi12sio20thinfilms |
| first_indexed |
2025-07-08T18:10:58Z |
| last_indexed |
2025-07-08T18:10:58Z |
| _version_ |
1837103327402262528 |
| fulltext |
Condensed Matter Physics, 1999, Vol. 2, No. 4(20), pp. 625–630
Conductivity of the Bi 12SiO20 thin films
S.N.Plyaka, G.Ch.Sokolyanskii, E.O.Klebanskii,
L.Ja.Sadovskaya
Dnipropetrovsk State University,
20 Kazakova Str., 320625 Dnipropetrovsk, Ukraine
Received November 3, 1998, in final form November 1, 1999
The results of the conductivity examination in the Bi12SiO20 thin films pre-
pared using the sol-gel method are presented. The conductivity was inves-
tigated in the 300–550 K temperature and up to 100 V/cm field ranges. It
was observed that the charge carrier transfer at the flow level, situated in
the tail of the density of states into the forbidden band is dominant for the
investigated sample at T > 500 K. The obtained results are explained in
terms of the highly compensated doped semiconductor model.
Key words: bismuth sillenite, thin film, sol-gel method, conductivity
PACS: 73.61
Bismuth sillenite Bi12SiO20 (BSO) is an attractive material for active optical
devices. Most of these devices were made with the BSO single crystals. But it is
desirable to make BSO thin films both for optical processing devices and for scientific
investigations, for example for the optical absorption edge investigation. Among
various techniques of dielectric thin film preparation the sol-gel processing is one of
the most promising. In this paper the results of the conductivity examination in the
BSO thin films prepared by sol-gel method are presented.
BSO thin films were obtained from the fresh precursor prepared by dispersing
the starting materials (Bi2O3, SiO2) in an organic solvent. The silicon plane-parallel
plates with platinum coverage were used as the substrates. In order to obtain the
films of the desired thickness, several layers were deposited and each layer was
heated at 673 K in the air. Film thickness was evaluated by weighing and its value
was ∼ 10−5 cm for each layer. Annealing at 923 K during 1 hour was carried out for
BSO crystal structure fabrication of the film. The film conductivity σ in the tem-
perature range 300–550 K at E = 100 V/cm in the direction of the perpendicular to
the film plate was investigated. The VK 2-16 voltmeter (I < 10−8A) and microam-
permeter (I > 10−8A) were used for the current measurements. Platinum electrode
on the substrate was the anode.
Temperature dependence of the BSO film conductivity is given in figure 1. At
room temperature σ is ∼ 10−10 Om−1cm−1. The obtained results strongly differ from
c© S.N.Plyaka, G.Ch.Sokolyanskii, E.O.Klebanskii, L.Ja.Sadovskaya 625
S.N.Plyaka et al.
2,0 2,5 3,0 3,5
-10
-9
-8
-7
-6
-5
Lg
σ
, Ω
-1
cm
-1
1/T 10
-3
, K
-1
Figure 1. Temperature dependence of the conductivity of the Bi12SiO20 thin
films.
the data in [1] where σ is ∼ 10−14 Om−1cm−1 (T = 300 K). In the latter case, BSO
thin films have been prepared on the glass substrates by ECR plasma sputtering with
aluminum electrodes. The σ distinction is possibly connected with the technology of
the film preparation. As may be seen from figure 1, the conductivity increases with
the temperature. The curve slope on the plot is not constant, the activation energy
Ea increases from 0.44 eV to 0.83 eV. Above 500 K, the Ea remains constant with
the value 0.83 eV.
The current-voltage (C-V) characteristics have got some special features (fig-
ure 2).
1. There are several sub-regions on the I ∼ Uα dependence: ohmic, square-law
regions and the region of the abrupt rise in current.
2. On the region of the abrupt rise in current the α value changes from 2 to 8. The
transition from the σ ohmic dependence to the quadratic one is continuous.
626
Conductivity of the Bi12SiO20 thin films
-1,5 -1,0 -0,5 0,0 0,5
-11
-10
-9
-8
-7
-6
-5
-4
-3
6
5
4
3
2
1
Lg
I,
A
Lg U, V
Figure 2. Current-voltage curves of the Bi12SiO20 thin films at temperatures: 1
– 293 K; 2 – 323 K; 3 – 373 K; 4 – 423 K; 5 – 473 K; 6 – 523 K.
3. There is a region of the C-V dependence where α remains constant with the
value 1.9–2.4.
The described peculiarities of the C-V characteristics can be connected both
with the film bulk features and with the contact effects, for example the Schottky
emission. In order to choose the mechanism type, the log I = f(U 1/2) curve was
investigated which should be a straight line if the current is conditioned by Schot-
tky emission [2]. In our case, such a curve was not straight. We may say that C-V
curves are defined in general by the film bulk properties in the investigated tem-
perature and field ranges. As it was noted above, several coatings were deposited
one upon the other to obtain the films of the thickness desired. So the “barrier”
mechanism of conductivity can be one of the possible mechanisms. Then the sam-
ple total resistance is determined by the sum of the barrier resistance formed on
the coating boundaries and of the resistance of coatings successively joined. In the
latter case, the activation energy is the linear function of the applied voltage and it
627
S.N.Plyaka et al.
1,5 2,0 2,5 3,0 3,5
-10
-8
-6
-4
-2
1
2
3
4
5
6
8
7
Lg
I
,
A
1/T 10
-3
, K
-1
0,0 0,4 0,8 1,2 1,6
0,2
0,4
0,6
E
a ,
e
V
U, V
Figure 3. Temperature dependence of the current in Bi12SiO20 thin films sub-
jected to different voltages U(V): (1) 0.4; (2) 0.5; (3) 0.6; (4) 0.7; (5) 0.8; (6) 1.0;
(7) 1.2; (8) 1.5. The inset shows the activation energy of conduction Ea plotted
as function of the voltage U.
should decrease with the voltage increasing [3]. The temperature dependence of the
conductivity at different voltage values is presented in figure 3. These curves were
obtained from the C-V characteristic measurements. As may be seen in figure 3, the
slope of the curves decreases with the increasing voltage. The Ea values calculated
are given in figure 3. The Ea value decreases from 0.7 eV (ohmic region) to 0.22 eV.
The Ea does not decrease for higher voltages. Such Ea(U) dependence is in contra-
diction with [3]. So we assume that “barrier” effects are not determinative in the
conductivity mechanism of the obtained films.
Thus C-V characteristics and Ea(U) curves permit us to say that the deep traps
control the current across a given structure. According to [4], the form of the Ea(U)
curves (figure 1 and 3) can be observed when the traps distribution is Gaussian.
In this case, the hopping charge transport mechanism may take place. The charge
carrier jumps may be realized on the flow level, at the state of density maximum
628
Conductivity of the Bi12SiO20 thin films
as well as at the states near Fermi level. The variable jump length is typical of
the transfer at the states near Fermi level. But we did not observe such cases. The
activation energy depends on the applied voltage for hops on the maximum of the
state density. The Ea decreases as the result of the local state filling due to injection.
The Fermi level shifts to the larger density of the local states. This corresponds to
the Ea decrease and to the conductivity increase. In the case of the injection ability
limited, the Ea does not depend on voltage. The conductivity has the variable Ea
with the increasing temperature. In our case, such a dependence is observed at T <
500 K. The activation energy constant at a different voltage and the high effective
mobility are the characteristic peculiarities of the transfer at the flow level in the
“tail” part of the state density. Starting from the C-V curves and time-of-flight
investigations at t > 500 K, the effective mobility is about 10−2cm2V−1c−1. Thus
the charge carrier transfer at the flow level, situated in the tail of the density of
states into a forbidden band is dominated for the sample investigated at T > 500 K.
These states emerge due to the disorder distribution of the impurities of the doped
materials at a strong compensation.
The results obtained in this work agree with those of the investigation of transfer
mechanism in Bi12SiO20 single crystals well [5,6]. The different conductivity and
activation energy values for films and single crystals may most probably be caused
both by various concentrations of the local states and by the different power of the
compensation in the crystals and in the films.
References
1. Malinovskyi V.K., Gudaev O.A., Gusev V.A., Demenko S.I. Fotoinductional Phenom-
ena in Sillenites. Nauka, 1990 (in Russian).
2. Zyuganov A.N., Svechnikov S.V. Injection-Contact Phenomena in Semiconductors.
Kiev, 1981 (in Russian).
3. Bakh N.A., Vannjikov A.V., Grishina A.D. Electroprovodnost i paramagnetizm
polimernykh poluprovodnikov. Nauka, Moskva, 1971 (in Russian).
4. Nespurek S., Silinch E.A. // Phys. Stat. Sol. (a), 1976, vol. 34, p. 747–759.
5. Bunina L.K., Kudzin A.Yu., Sokolyanskii G.Ch., Yudin A.S. // Sov. Phys. Solid State,
1992, vol. 34(2), p. 461–466.
6. Bunina L.K., Kudzin A.Yu., Sokolyanskii G.Ch. // Sov. Phys. Solid State, 1988,
vol. 30(1), p. 266–267.
629
S.N.Plyaka et al.
Провiднiсть тонких плiвок Bi12SiO20
С.Н.Пляка, Г.Х.Соколянський, Е.О.Клебанський,
Л.Я.Садовська
Днiпропетровський державний унiверситет,
320625 Днiпропетровськ, вул. Казакова, 20
Отримано 3 жовтня 1998 р., в остаточному вигляді – 1 жовтня
1999 р.
Тонкi плiвки сiленiту вiсмуту були отриманi золь-гель методом. У ши-
рокому діапазонi полів та температур були дослiдженi вольт-ампернi
характеристики та електропровiднiсть. Знайдено, що перенесен-
ня носiїв заряду в тонких плiвках при T > 500 K здiйснюється по
рiвню протiкання, розташованому у хвостi густини локалiзованих
станiв. Отриманi результати обговорюються у рамках моделi легова-
них компенсованих напiвпровiдникiв.
Ключові слова: електропровiднicть, вольт-амперна
характеристика, енергiя активацii, густина локалiзованих станiв
PACS: 73.61
630
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