Volume 02 Issue 06-2022
96
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
A
BSTRACT
In this work, a study of the anomalous photovoltaic effect (APhN - effect) in crystalline dielectrics was
carried out. The nature of the effect is explained according to polarization processes. It is shown that in
dielectrics, due to high thermal ionization photoionization energies, impurity complexes of the cluster type
are mainly involved in the formation of the effect. Segregation of cluster complexes, apparently, under the
action of polarized (coherent) light is activated and stimulates the formation of electrode domain walls.
The electrons and holes separated by light will accumulate only in the domain walls, thus creating an
elementary voltage (on the order of KT/q) on each domain wall. These elementary stresses are summed
up at macro distances and lead to an abnormally high voltage.
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
ANOMALOUS PHOTOVOLTAIC EFFECT IN DIELECTRICS
Submission Date:
June 10, 2022,
Accepted Date:
June 20, 2022,
Published Date:
June 30, 2022
Crossref doi:
https://doi.org/10.37547/ijasr-02-06-12
Nurdinova Raziyakhon Abdikhalikovna
Associate Professor, Fergana branch of the Tashkent University of Information Technologies named after
Muhammad al-Khwarizmi, Fergana, Republic of Uzbekistan
Rayimjonova Odinahon Sodikovna
Associate Professor, Fergana branch of the Tashkent University of Information Technologies named after
Muhammad al-Khwarizmi, Fergana, Republic of Uzbekistan
Ergashev Shohbozjon Umarali ugli
Assistant, Fergana branch of the Tashkent University of Information Technologies named after Muhammad
al-Khwarizmi, Fergana, Republic of Uzbekistan
Tillaboyev Muhiddin G’anijonovich
Assistant, Fergana branch of the Tashkent University of Information Technologies named after Muhammad
al-Khwarizmi, Fergana, Republic of Uzbekistan
Volume 02 Issue 06-2022
97
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
K
EYWORDS
APhN - effect, polarization, photo, thermal ionization, cluster complexes, segregation, ferroelectrics, Curie
point, dielectric constant, unit cell, perovskite, total polarization, dipole, dipole moment, electric domains,
domain walls, domain stimulation and domain orientation.
I
NTRODUCTION
The development of technology in recent years is
characterized by the widespread use of
crystalline dielectrics. Thus, the successful
development of quantum radio electronics,
piezotechnics,
electroacoustics,
measuring
technology, etc. is now unthinkable without the
use of crystalline dielectrics. Only a complete
knowledge of all the properties of crystalline
dielectrics makes it possible to judge the
prospects for its application in technology. The
effects of anomalous photomagnetic voltage
(APMV) in thin polycrystalline semiconductors
have long been known [1-2]. There are a lot of
works in this direction, the stages in the
development of new physics in the technique and
technology of the AFN - effect in thin
semiconductor films were the works of E.I.
Adirovich, R. Naimanbaev, S. Otazhonov and
others [3]. Theories of the effect are developed
and the areas of application of the AFN-effect are
determined. However, studies of the AFN - effect
in dielectrics are still at the initial stage of
development. The effect of anomalously high
photovoltages has been observed experimentally
in a number of dielectrics (ferroelectrics). There
are still few works in this area [4-6].
Ferroelectrics are called crystalline substances of
the dielectric type, in which, in the absence of an
external electric field, spontaneous polarization
occurs in a certain range of temperatures and
mechanical stresses, the direction of which can be
changed by an electric field and, in some cases,
mechanical stresses. Ferroelectric crystals are
divided into separate regions (domains) that
differ in the direction of spontaneous
polarization.
Polarization is a multi-valued function of E. The
value of P corresponding to saturation is denoted
Ps and for a typical ferroelectric BaTiO3 it is 0.26
k/m2 at room temperature. The remanent
polarization PR is the polarization that persists
when, after saturation, the field E is reduced to
zero. To reduce the polarization P to zero, it is
necessary to apply a field of the opposite
direction; this field is called the coercive force EC.
PR and EC values depend not only on the nature
of the material, but also on other factors such as
impurities, crystallite size and heat treatment
(Fig. 1)
Volume 02 Issue 06-2022
98
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
Fig.1. Hysteresis loop of a ferroelectric
Fig.2. Ferroelectric domains
The general similarity of the hysteresis loops of
ferroelectrics with the hysteresis loops of
ferromagnets naturally led to the search for
ferroelectric domains and they were found in
BaTiO3 (Fig. 2). Inside an individual domain, the
polarization coincides with the crystallographic
Volume 02 Issue 06-2022
99
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
direction. The total polarization of a massive
piece of material is the vector sum of the
polarizations of all domains, and the contribution
of each domain is proportional to its volume. If an
electric field is applied to such a crystal, the
following phenomena can be observed:
1)
Polarization can vary in magnitude in each
domain;
2)
Domain polarization can change its
direction;
3)
The most favorably oriented domains, i.e.,
those domains whose polarization makes
a small angle with the vector E, can grow
due to the displacement of the boundaries
between the domains. Each of these three
processes changes the overall polarization
of the entire solid.
The nature of spontaneous polarization has been
studied only partially. In reality, the details of the
phenomenon may be somewhat different for each
of the ferroelectrics. In addition, understanding
the nature of the phenomenon is complicated by
the fact that various ferroelectric materials have
complex crystal structures. However, in one of the
substances, BaTiO3, the structure is simple
enough to reveal the atomic configuration that
leads to spontaneous polarization.
Fig.3. Unit cell of barium titanate
Volume 02 Issue 06-2022
100
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
The elementary cubic cell of this material is
shown schematically in Fig.3. In this cell (a
perovskite-type structure), the Ba ions are
located at the corners of the cube, the Ti ion is in
the center of the cube, and the O ions are in the
centers of the cube faces. The elementary cell of
such a structure does not have a dipole moment,
since all charges are arranged symmetrically. If,
however, the Ti and O ions are displaced relative
to the Ba ions, dipoles with a certain configuration
are formed. Let us assume that the Ti ion is
displaced in the direction of the O ion located on
one of the faces of the cube; in this case, the
elementary cube acquires a dipole moment in the
indicated direction. If such a displacement of Ti
ions occurs in all unit cells of the crystal, then the
total polarization of the entire solid occurs. From
the value of Ps measured for ВаТiO3, it can be
calculated that a shift of the Ti ion by only 0.1 A
would be quite sufficient to obtain the observed
effect. Therefore, the considered model is very
plausible. The latest research has shown that in
ВаТiO3 there is, apparently, a displacement of
both Ti and O ions, but in each pair of ions these
displacements occur in opposite directions.
Spontaneous polarization of ferroelectrics is
preserved, not up to their melting points. For
every material, it exists at low temperatures up to
a certain maximum temperature, called the
ferroelectric Curie point. Apparently, the strong
motion of atoms at temperatures exceeding the
Curie temperature Tc is sufficient to destroy the
effect of directed displacement of ions in
neighboring unit cells. The relative permittivity of
ferroelectrics is of less interest than r of normal
dielectrics, since this value changes with the
electric field (E). However, if it is defined in this
case as well, then using expression (1) it is
possible to compare ferroelectrics with normal
dielectrics,
𝑃 = 𝜀
𝑉
∙ 𝑥
𝑒
∙ 𝐸
1), где
𝜀
𝑉
=
𝜀
𝜀
𝑟
,
𝑃 = 𝜀
𝑉
∙ (𝜀
𝑟
− 1)𝐸
,
𝜀
𝑟
− 1 = 𝑥
𝑒
(1)
dielectric
susceptibility.
In
isotropic
dielectrics, the D, P, and E vectors have the
same directions.
𝐷 = 𝜀 ∙ 𝐸
,
𝐷 = 𝜀
𝑉
∙ 𝐸 + 𝑃
,
𝐷 = 𝜀
𝑉
∙
𝜀
𝜀
𝑉
,
𝐸 = 𝜀
𝑣
∙ 𝜀
𝑟
∙
𝐸
,
𝜀 = 𝜀
𝑣
∙ 𝜀
𝑟
(2)
The value of ferroelectrics is usually much
greater than that of other solid dielectrics at
the same electric field strength. For example,
an ordinary dielectric mica has a relative
permittivity (independent of E) of the order
of 7.
The relative permittivity of the BaTiO3
ferroelectric at room temperature in a field of
106 V/M is on the order of several thousand
(from 3·10
3
to 5·10
3
).
The polarization of individual atoms and
molecules in an electric field can be due to
three reasons:
1.
An electric field can cause a relative
displacement of the positive and negative
charge in an atom, inducing a dipole
moment on the atom.
Volume 02 Issue 06-2022
101
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
2.
Positively and negatively charged ions can
also experience a shift under the action of
the field, causing ionic polarization.
3.
Permanent dipoles (ie, dipoles that exist
in the absence of an external field) can be
rotated by the field from random
directions in the direction of the field,
causing polarization to occur due to the
orientation of the permanent dipoles.
Sets of spontaneously polarized unit cells
form regions called domains. In ferroelectrics
within each domain, all unit cells are oriented
in the same way, the domains in this case
have
a
macroscopic
spontaneous
polarization, in neighboring domains of
ferroelectrics they make certain angles with
each other. When considering possible
boundaries
between
domains
in
ferroelectrics, one should take into account
not only geometric considerations, but also
the condition of electrical neutrality of the
boundary, which corresponds to the
minimum energy of the crystal. This
necessitates such an orientation of the dipole
in neighboring domains, in which the
projection of the polarization vector onto the
boundary from the sides of one domain is
equal in magnitude and opposite in sign to
the projection of the polarization vector of
the other (neighboring) domain (the
orientation of domains according to the
“head” of the dipole of some domains sticks
to “ tail” of the dipole of neighboring
domains).
It is known that the degree of polarization
and the absorption process are interrelated.
In the process of polarization of dielectrics,
energy is accumulated in the crystal by
means of internal and external fields. Exactly
this situation occurs during absorption
(reflection, transmission of light by a
dielectric). In ferroelectrics, the main role in
the process of polarization is played by the
domain walls of crystals of polycrystalline
and single-crystal dielectrics. In this work,
we study the APV effect in a metastable,
orthorhombic titanite (BaTiO3) single
crystal. The single crystal was grown by the
Czochralski method [5]. Samples of BaTiO3
single
crystals
were
rectangular
parallelepipeds 2x2x1mm3 in size. The faces
of the samples were perpendicular to the
[001]
polar
axis,
along
which
the
spontaneous polarization was directed. The
potential difference between the faces was
measured. Measurements were made using
an electrometer (Cactus). The resistance of
the samples is not less than 10^12 m.
Subsequent experiments showed that the
generation and recombination of carriers in a
titanite sample is primarily affected by
shallow energy levels, and that domain walls
do not play an important role in the
formation of an anomalous photovoltaic
effect in a single crystal of the ferroelectric
dielectric BaTiO3.
At present, interest in the study of
ferroelectrics and hybrid dielectric materials
is growing. Using these materials, it is
possible to produce highly efficient solar
Volume 02 Issue 06-2022
102
International Journal of Advance Scientific Research
(ISSN
–
2750-1396)
VOLUME
02
I
SSUE
06
Pages:
96-102
SJIF
I
MPACT
FACTOR
(2021:
5.478
)
(2022:
5.636
)
METADATA
IF
–
7.356
cells, which are widely used in various fields
of science and technology [7-10].
R
EFERENCES
1.
Райимжонова, О. С., Тажибаев, И. Б., &
Тошпулатов, Ш. М. (2021). Телевизион
тасвир сигналлари спектрини зичлаш
(сиқиш) усуллари таҳлили.
Scientific
progress
,
2
(6), 235-244.
2.
Raimimonova, O. S., & Iskandarov, U. U.
(2020). Overview of the experimental
reasarche of open optical system for
monitoring of deviations of the buildings with
concrete products.
Scientific Bulletin of
Namangan State University
,
2
(6), 374-378.
3.
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.
4.
Raimimonova O. S.,
Nurdinova R.A.,
R.Dalibekov,
Sh.M.Ergashev
(2021).
Increasing
the
possibility
of
using
thermoanemometric type heat exchangers in
the control of man-madt objects.
International
Journal of Advanced Research in Science,
Engineering and Technology
. 8(3), 16783 – 89.
5.
Shipulin, Y. G., Raimzhonova, O. S., Ergashev,
O. M., & Usmanov, Z. K. (2021). Method for
Ensuring
Continuous
Functioning
of
Multichannel Systems for Control and
Recording of Water Composition in Seismic
Wells.
6.
O.Kh.
Kadirov,
Yu.G.,
Shipulin,
A.A.
Kakhkharov. (2019). The Multipurpose
converter for control of Parameters of
Gaseous Environments.
International Journal
of Advanced Research in Science, Engineering
and Technology
. 6(5), 9155 – 60.
7.
Yuldashev,
K.
T.
(2020).
Research
photoelectric
and
photographic
characteristics of the converter of the image of
the ionization type.
Scientific Bulletin of
Namangan State University
,
2
(10), 16-22.
8.
Yuldashev, K. T., & Akhmedov, S. S. (2021).
Physical
properties
at
the
contact
semiconductor-Gas discharge plasma in a thin
gas discharge cell.
Asian Journal of
Multidimensional Research
,
10
(9), 569-573.
9.
Yuldashev, H. T., & Mirzaev, S. Z. (2021).
Investigation of background radiation and the
possibility of its limitation in a semiconductor
ionization
system.
ACADEMICIA:
An
International
Multidisciplinary
Research
Journal
,
11
(4), 1364-1369.
10.
Yuldashev, K. T., Akhmedov, S. S., & Ibrohimov,
J. M. (2020). Damping cell from gallium
arsenide with plasma contacts in an extreme
gas discharge cell.
Journal of Tashkent Institute
of Railway Engineers
,
16
(1), 36-41.
