Volume 02 Issue 12-2022
149
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
A
BSTRACT
In this paper, we consider the frequency dependence of the resistance of PbTe films. Establishing that the
resistance of films containing an excess of lead up to 0.2 wt% decreases with increasing frequency of the
supply voltage, and for samples containing more than 0.2 wt%, an increase in resistance is observed. At
ω=3 10
5
, the difference in the resistance of the films decreases significantly and the resistance weakly
depends on the frequency of the alternating signal
K
EYWORDS
Polycrystalline film, semiconductor, strain sensitivity, strain, resistivity.
Journal
Website:
http://sciencebring.co
m/index.php/ijasr
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Research Article
INVESTIGATION OF THE FREQUENCY DEPENDENCE OF THE
RESISTANCE OF PbTe FILMS
Submission Date:
December 11, 2022,
Accepted Date:
December 16, 2022,
Published Date:
December 21, 2022
Crossref doi:
https://doi.org/10.37547/ijasr-02-12-22
T. Akhmedov
Candidate Of Physical And Mathematical Sciences, Associate Professor, Fergana State University, Fergana,
Uzbekistan
S.M. Otazhonov
Doctor Of Physical And Mathematical Sciences, Professor, Lecturer, Fergana State University, Fergana,
Uzbekistan
M.M. Khalilov
Fergana Branch Of The Tashkent University Of Information Technologies Fergana State University,
Fergana, Uzbekistan
Volume 02 Issue 12-2022
150
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
I
NTRODUCTION
On the basis of narrow-gap and wide-gap
semiconductors, photoreceivers [1], high-
temperature diodes [2], and the electrical
conductivities and diffusions of minority carriers
in thermally oxidized thin PbTe films [3], the
effect of oxygen on the transport properties in
polycrystalline PbTe films [4], and structural and
optical properties of undoped and antimony
doped lead telluride thin films [5] and the effect
of nonstoichiometry on the oxidation processes in
n-type PbTe thin films [6]. In the study by the
authors of [7], an infrared photoelectric property
was found on columnar films of PbTe doped with
tellurium. Despite the large number of works [8,
9, 10], along with the advantages, film elements of
PbTe semiconductor compounds also have a
number of disadvantages. The latter include -
insufficient stability, poor reproducibility of
structurally sensitive properties. The elimination
of these shortcomings requires an in-depth study
of the physics of the processes occurring in
inhomogeneous semiconductor films. In this
regard, we studied the effective permittivity and
electrical conductivity of polycrystalline PbTe
films with disturbed stoichiometry.
Experimental
technique
and
discussed
experimental results
One of the most effective methods for studying
the mechanisms of electrical conductivity of
inhomogeneous structures is to study the
dependence of resistance on an alternating signal.
If the film structure under study contains
electrically active inhomogeneities surrounded
by space charge regions, then on the signal
variable, the contribution to the electrical
conductivity will be made by capacitances
associated with inhomogeneities. Moreover, with
an increase in the frequency of the alternating
signal, the contribution to the total electrical
conductivity of the regions containing electrical
inhomogeneities will change.
The measurement of the frequency dependences
of the resistance of the PbTe films was carried out
according to the scheme of a DC generator in the
frequency range ω=(0÷106)Hz. Figure 1 shows
the dependences of the resistances of samples of
stoichiometric composition and with an excess of
tellurium of 0.8 and 3.8 wt.% on the frequency of
the
supply
sinusoidal
voltage.
Similar
dependences were obtained for samples with a
different Te excess content. As can be seen from
the figure, a sharp decrease in the resistance of
the films begins at frequencies of ~105 Hz. The
difference in film resistances for samples with
different contents of excess components is the
greater, the lower the frequency of the supply
signal. At ω>3*105 Hz, the difference in the
resistance of the films decreases significantly and
the resistance weakly depends on the frequency
of the alternating signal. Films containing
Volume 02 Issue 12-2022
151
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
superstoichiometric lead behave differently. The
resistance of films containing an excess of lead up
to 0.2 wt.% decreases with increasing frequency
of the supply voltage, and for samples containing
more than 0.2 wt.%, an increase in resistance is
observed. This is clearly seen from the I
–
V
characteristics of specimens with excess lead (see
Fig. 2) at ΔPb≤0.2 wt%, with an increase in the
frequency of the alternating signal, the slope of
the I
–
V characteristic increases, which indicates a
decrease in the resistance of the films (see curves
1, 2), and for ΔPb>0.2 wt.%
the slope of the CVC
decreases (curves 3.4). After heat treatment in
air, the dependences R(ω) for all samples are
similar to the data in Figs. 1 and 2.
Fig.1. Frequency dependence of the resistance of PbTe films with an excess of Te. ΔTe, weight%: 1
-
0; 2-0.8; 3-3.8.
Volume 02 Issue 12-2022
152
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
Fig.2. I
–
V characteristics of PbTe-Pb (1.2) and Pb-Te (3.4) films with an excess of lead at different
frequencies of the supply signal. ω,
Hz: 1.3-0; 2.4-4*10
5
.
The decrease in the electrical conductivity of
PbTe films upon thermal treatment in air is
explained by the increase in barriers in the
interaction of the films with oxygen. PuTe with an
excess of lead of 2.2 wt.%, the activation energy of
electrical conductivity is 1.5 10-2 eV (without
heat treatment) [11]. After heat treatment, ∆Еа
increases to -0.1 eV while maintaining the type of
conductivity, which undoubtedly indicates an
increase in the height of intercrystalline barriers
due to the influence of adsorbed diffused oxygen.
In favor of the fact that the decisive factor in the
formation of potential barriers is the interaction
with oxygen is also evidenced by the fact that the
films obtained at low Tn in a short time of heat
treatment become more high-resistance. And it is
known that the smaller Tn, the more dispersed
the film, therefore, the more channels in the tanks
through which the films interact with oxygen. In
the case of p-type films (with an excess Te) of
conductivity, the formation of barriers can occur
due to the existence of localized states for holes at
the crystallite boundaries, as well as the existence
of a Te phase with a different carrier
concentration (the formation of nonideal
heterojunctions at the PbTe-Te interface). It
should be noted that the ratio of the electrical
conductivity of films to the electrical conductivity
of single crystals (σМ) at the same carrier
concentration
𝜎
𝜎
М
⁄
, observed experimentally is
much less than exp
((-
∆E_a)⁄kT), i.e.
𝜎
М
𝜎
> exp(
∆𝐸
𝑎
𝑘𝑇
)
Where ∆Еа is the value of the activation energy. It
can be assumed that the factor σ0 is less than σМ.
this suggests that in the crystallites themselves
there is a fluctuation of the energy zones of a
smaller scale than at the boundaries of the
crystallites [12]. Scattering of carriers on the
humps of such small-scale fluctuations leads to a
dispersion of their mean free path and a decrease
in the mobility in the crystallites themselves. In
this regard, in σ0<<σМ. The permittivity of a
substance is determined by the e ε=1+4πX_e,
where , X_a=P⁄E is the electrical susceptibility,
which is determined by the internal properties of
the substance and depends on the polarizability
of each atom. The total dipole moment (
Ṗ
) of a
unit volume of a crystallite depends on the values
of the dipole moment of the atoms, and the
number and geometric arrangement. The
combination of atoms into a molecule and the
formation of crystallites can change the electronic
structure and hence the polarizability.
PbTe-Te, PbTe-Pb films are heterogeneous
systems consisting of PbTe, Te, Pb. Lead telluride
Volume 02 Issue 12-2022
153
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
and lead have a cubic lattice, while telluride has a
hexagonal one [13]. Therefore, PbTe-Te films
with excess superstoichiometric Te are a system
consisting of tare-shaped (PbTe) and ellipsoidal
(Te) formations, and PbTe - Pb - only tare-shaped.
in the structures of PbTe, Pb, Te atoms there are
weakly bound valence electrons. Therefore,
atoms are easily deformed by an electric field. The
electric field causes a relative displacement of
free carriers in crystals. Crystallites can have an
electric dipole moment if the “centers of gravity”
of the positive and negative charges do not
coincide. The high value of the effective
permittivity
𝜀
𝑒𝑓𝑓
∗
in the microwave range is
associated with the establishment of full
polarization in all regions of the film. An increase
in ε_eff^* with an increase in the Te addition is
due to an increase in the number of ellipsoidal
inclusions, which have a large dipole moment.
Small values of ε_eff^* in the IR frequency range
-
by establishing a weak polarization due to the
difference in relocation times [14]. The
absorption coefficient (the imaginary part of the
permittivity) is determined by the electronic
transitions that occur when light interacts with a
semiconductor. The dependences of the
calculated values of
𝚥
𝑚
𝜀
𝑒𝑓𝑓
∗
and the experimental
values of the emission coefficient on the light
energy are similar for all films under
consideration.
This
shows
that
the
experimentally observed change in the
absorption spectra of PbTe-Te and PbTe-Pb films
is due to a change in their effective permittivity
depending on the volume fraction of
superstoichiometric Te and Pb. It is known that at
the boundary of two media with different
polarization (
Ṗ
1,
Ṗ
2) the electric field strength
jump is equal to their difference (∆Ṗ
=
Ṗ
1 -
Ṗ
2). In
other words, the interface between two media, on
which the polarization changes by a certain
magnitude, has the same effect on the magnitude
of the electric field as does the surface of the div
on which the real charge is located. Consequently,
in the case of uniform polarization, a surface
charge with a density σ equal to ∆Р per unit area
is formed at the crystallite boundary, which leads
to a change in the height of intercrystallite
barriers in PbTe
–
Te films. The sublinear current-
voltage characteristic in PbTe
–
Te films can be
explained by the modulation of structural
barriers by polarization ones: with an increase in
the applied voltage, the barriers at the boundaries
of crystallites increase nonlinearly, which leads to
an increase in the resistance of the films to the
field.
C
ONCLUSION
Comparison of the experiment with the
qualitative results of the present work shows
satisfactory agreement. It can be concluded that
the features of the kinetic effects in
polycrystalline PbTe films of nonstoichiometric
composition are due to the inhomogeneity of the
potential relief of the films.
Volume 02 Issue 12-2022
154
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
R
EFERENCES
1.
Z.F. Agaev, G.Z. Bagieva, J.Z. Naftalieva, B.Sh.
Barkhalov. Solid State Physics. 2008. No. 3. pp.
92-94.
2.
G.Z. Bagieva, G.M. Murtuzov, G.D. Abdinova,
E.A. Allahverdiev, D.Sh. Abdinov. Inorganic
materials. 2012. T. 48, No. 8. pp. 901-904.
3.
G.Z. Bagieva, N.B. Mustafaev, G.J. Abdinov.
Physics and technology of semiconductors.
2011. T. 45, No. 11. pp. 1446-1448.
4.
Yu.Yu. Vaitkus, S.M. Otazhonov, M.M. Khalilov,
N. Yunusov. Scientific Bulletin. Physical and
Mathematical Research Vol. 3 Iss. 1. June
2021. Andijon. Uzbekistan.
5.
S.M. Otazhonov, K.A. Botirov, M.M. Khalilov.
ISSN 2308-4804. science and world. 2021. No.
6 (94).
6.
Otazhonov S.M. Khalilov, M. Boyboboev R.Kh.
Yunusov N. Mamajonov U.M. pp. 329-334.
Proceedings of the 1st International Scientific
and Practical Conference Current issues and
prospects for the development of scientific
research Orléans, France 19-20.03.2021
7.
Otazhonov S.M. Botirov K.A. Khalilov M.M.
Yunusov N. Abdumalikova M. pp. 954-962
Proceedings of the 1st International Scientific
and Practical Conference Theory and practice
of science: Key aspects. Rome, Italy 19-
20.02.2021.
8.
Akhmedov, T., Otazhonov, S. M., Khalilov, M.
M., Yunusov, N., Mamadzhanov, U., & Zhuraev,
N. M. (2021, December). Effective dielectric
permeability and electrical conductivity of
polycrystalline PbTe films with disturbed
stochiometry. In Journal of Physics:
Conference Series (Vol. 2131, No. 5, p.
052008). IOP Publishing.
9.
Akhmedov, T., Otajonov, S. M., Usmonov, Y.,
Khalilov, M. M., Yunusov, N., & Amonov, A. K.
(2021,
April).
Optical
properties
of
polycrystalline films of lead telluride with
distributed stichiometry. In Journal of
Physics: Conference Series (Vol. 1889, No. 2, p.
022052). IOP Publishing.
10.
Dashevsky Z, Shuzterman S., Dariel M.P.,
Drabkin I. Journal of Applied Physics. 2002. V.
92, №3. pp. 1425
-1430.
11.
Dzundza, B., Nykyruy, L., Parashchuk, T.,
Ivakin, E., Yavorsky, Y., Chernyak, L., &
Dashevsky, Z. (2020). Transport and
thermoelectric performance of n-type PbTe
films. Physica B: Condensed Matter, 588,
412178.
12.
Отажонов, С. М., Ахмедов, Т., Халилов, М. М.,
Усмонов, Я., & Мамаджонов, У. М. (2013).
Влияние
термообработки
на
электрофизические
свойства
поликристаллических пленок теллурида
свинца. SCIENCE AND WORLD, 12.
13.
Otazhonov S.M., Khalilov M.M., Yunusov N.,
Akhmedov T., Mamajanov. ISSN 2308-4804.
Science and world
. 2021. № 7 (95). Volgograd,
2021.
14.
Otazhonov, S. M., Kh, R. M., Khalilov, M. M.,
Botirov, K. A., & Yunusov, N. (2021). Effect of
Volume 02 Issue 12-2022
155
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
12
Pages:
149-155
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
group VII elements on strain sensitivity of
polycrystalline films PbTe, PbS. European
science review, (1-2), 35-38.
15.
Rayimjonova, O. S. (2022). Investigation of
cluster-type
inhomogeneity
in
semiconductors. American Journal of Applied
Science and Technology, 2(06), 94-97.
16.
Райимжонова, О. С., Тажибаев, И. Б., &
Тошпулатов, Ш. М. (2021). Телевизион
тасвир сигналлари спектрини зичлаш
(сиқиш) усуллари таҳлили. Scientific
progress, 2(6), 235-244.
17.
Азимов, Р. К., Шипулин, Ю. Г., &
Райимжонова, О. С. (2013). Устройство для
измерения скорости и определения
направления
горизонтального
ветра.
Сведения об авторах Шухрат Юрьевич
Шипулин.
18.
Rayimjonova, O. S., Yuldashev, K. T., Ergashev,
U. S., & Jurayeva, G. F. (2020). LR Dalibekov
Photo
Converter
for
Research
of
Characteristics
Laser
IR
Radiation.
International Journal of Advanced Research in
Science, Engineering and Technology, 7(2),
12788-12791.
