(Ismailov Shavkat Kuzievich)
†iD
(Saidov Amin Safarbaevich)
1iD
(Usmonov Shukrullo Negmatovich)
1iD
(Saparov Dadajan Valixanovich)
1iD
(Eshonkhojaev Dilmurod Odilovich)
1iD
(Asatova Umida Palvanovna)
2iD
(Bobojanov Sukhrob Gayratovich)
3iD
-
(Professor, Physico-Technical Institute of the Academy of Sciences of the Republic
of Uzbekistan E-mail: amin@uzsci.net, shukrullousmonov66@gmail.com, dada@uzsci.net,eshonxojayevdilmurod34@gmail.com)
-
(Professor, Urgench State University, Urgench, Uzbekistan E-mail: umida72@rambler.ru)
-
(Kumoh National Institute of Technology, Gumi-si, Gyeongsangbuk-do, South KoreaE-mail:
w.suxrob.w@gmail.com)
Copyright © The Korea Institute for Structural Maintenance and Inspection
Key words
solid solution, molecular substitution, epitaxial layer, heterostructure, spectral photosensitivity, nanocrystallites, near-ir regions of the radiation spectrum.
1. Introduction
Growing semiconductor solid solutions is of undoubted interest for the development
of modern semiconductor instrumentation, since a solid solution synthesized from several
semiconductor components can combine the advantages of each of them. The works [1-4] show that by preparing solid solutions with many components, it is possible to achieve
the desired molecular bond and symmetry of crystals, as well as accurately control
the cell size and obtain many other physicochemical properties. Solid solutions are
constantly being studied with the aim of rationally modifying structures and understanding
the principles of crystal packing.
When elemental semiconductors or semiconductor compounds do not meet the technical
requirements for a particular device, a new solid solution is synthesized from several
semiconductors that meets the requirements. It should be noted that, by smoothly varying
the composition of the solid solution, one can control the main electrophysical and
optical parameters of the material [5- 8], such as the band gap, spectral photosensitivity
region, lattice parameter, etc.
The paper [7] reviews solid solution strategies used in molecular conductors, where the main goal
is to control their transport and magnetic properties (metallic or superconducting
behavior, metal-insulator transitions, etc.).The main features of molecular conductors
are described to determine which molecular compounds are prone to being replaced by
others in solid solutions, to what extent and for what purpose.
In order to obtain a high-quality solid solution suitable for creating devices, the
closeness of the lattice parameters of the solid solution components is of great importance.
The crystal structure of InSb has a cubic syngony of the zinc blende type, with a
crystal lattice constant of 0.648 nm. Gray tin Sn also forms cubic crystals, with
a crystal lattice constant of 0.646 nm, with a diamond–like structure. Therefore,
they are promising pairs that form substitutional solid solutions of the (InSb)1–z(Sn2)z
type [9].
In this regard, the solid solution consisting of the components GaAs, ZnSe and InSb
of undoubted interest, since the sum of the covalent radii of the atoms of the molecules
of these semiconductors is very close [9, 10], and the band gaps in them (Eg) differ
significantly (Eg, GaAs = 1.43 eV, Eg, ZnSe = 2.68 eV and Eg, Ge = 0.67 eV) [11].
There is every reason to believe that a solid solution consisting of these components
will have a qualitative crystallographic structure, and the spectral sensitivity region
will cover the fundamental agreement regions of germanium, gallium arsenide, and zinc
selenide. The expansion of the region of spectral photosensitivity is of great importance
for the creation of efficient photovoltaic devices, including photodetectors and solar
cells. In this work, we studied the possibility of forming a solid solution of molecular
substitution based on GaAs, Ge, and ZnSe and identified the optimal technological
conditions for growing single-crystal epitaxial layers of a solid solution of molecular
substitution (GaAs)1-y-z(Ge2)y(ZnSe)z on GaAs substrates, as well as the atomic- force
microscopy of the epitaxial film surface and the spectral dependence of the n-GaAs–n+(GaAs)1-x-y(Ge2)x(ZnSe)y
heterostructure.
2. Materials and methods
The possibility of the formation of a solid solution of molecular substitution between
the GaAs, Ge, and ZnSe components was estimated based on the criteria given in formulas
(1) and (2) [11].
where zII, zIII, zIV, zV, zVI are the valences of atoms of groups II, III, IV, V,
and VI, rII, rIII, rIV, rV, rVI and rVI are the covalent radii of atoms of groups
II, III, IV, V, and VI, respectively.
According to these criteria, the valency of the mutually substituting components should
be the same (1) and the difference in the covalent radii of the molecules should not exceed 10%.
Since the sum of the covalent radii of the atoms of the GaAs, Ge, and ZnSe semiconductor
molecules is very close (rGa + rAs = 2.44 Å, rZn + rSe = 2.45 Å and rGe + rGe = 2.44
Å), and the sum of the valences of the atoms of the molecules are the same and equal
to 8, the criteria substitution solid solution formations (1) and (2) are performed. Therefore, it can be said that the GaAs, Ge, and ZnSe components can
form a substitutional solid solution with a good crystallographic structure.
The temperature of decomposition (formation) of the IV–IV, III–V, II–VI, I–VII, and
other compounds becomes a decisive factor for the formation of solid solutions of
these compounds. The temperature interval of the existence of the IV IV, III–V, II–VI,
I–VII, and new compounds is determined from the condition.
where EIV–VI ,EIII–V ,EII–VI, EI–VII are the energies of bonding between atoms of
the IV–IV, III–V, II–VI, and I–VII molecules, respectively; and N is the num ber of
atoms in the solid solution.
For the Ge–GaAs system considered as an example, we can expect that, at temperatures
close to the eutectic temperature (~860°C) and above, the Ge2 and GaAs molecules
are most likely unstable; consequently, the phase diagram of this system does not
contain regions of solid solu tions. The epitaxial growth of (Ge2)x(GaAs)1–x layers
usually proceeds at temperatures where the Ge2 and GaAs molecules are stable, and
the solid solution of the Ge2 and GaAs compounds is formed [12–15].
To grow such a solid solution between GaAs, Ge, and ZnSe, it is necessary to create
thermodynamic conditions, which were achieved on the basis of the liquid phase model
with molecular components proposed by A.S. Saidov. According to this model, semiconductor
compounds of the АIIIВVI and АIIВVI classes, as well as elementary semiconductors
such as Ge and Si, when dissolved in liquid metals (Ga, Sn, In. Bi. Pb, etc.) at temperatures
much lower than the melting point of the corresponding substances , are mainly in
the form of molecules (Fig 1). The solubility of binary compounds GaAs and ZnSe, as well as atomic substances
Ga, As, Zn, and Se, in Bi was studied at various temperatures.
Fig. 1. Dissolved molecules GaAs, ZnSe and Ge2 in Bi at 750° C.
The validity of this model for the selected Bi-GaAs-ZnSe system is confirmed by the
fact that the binary compounds GaAs and ZnSe in Bi have a very low solubility. While
their individual components, i.e. atomic substances Ga, As, Zn and Se, at the same
temperatures, have unlimited or very high solubility in Bi (Fig.3, 4). This shows
that the GaAs and ZnSe binary compounds dissolved in Bi at a temperature of 750°S
do not decompose into individual Ga and As atoms, as well as Zn and Se, but are in
the form of GaAs and ZnSe molecules.
Fig. 2. Dissolution of gallium arsenide in the form of GaAs molecules (a), as well
as gallium and arsenic in the form of individual Ga and As atoms (b) in Bi at a temperature
of 750°C.
Fig. 3. Dissolution of zinc selenide in the form of ZnSe molecules (a), as well as
zinc and selenium in the form of individual Zn and Se atoms (b) in Bi at a temperature
of 750°C [12–15].
3. Results and discussion
Epitaxial layers of the (GaAs)1-у-z(Ge2)y(ZnSe)z solid solution were grown on n-type
GaAs (111) substrates. The melt solution bounded between two horizontally arranged
substrates consisted of Bi, GaAs, Ge, and ZnSe. The thickness of the gap between the
substrates was varied in the range from 0.45 to 1.6 mm using special graphite props.
Growing temperature 750°S. The film thickness was 10–15 µm. The type of conductivity,
concentration, and mobility of carriers in the obtained epitaxial films of solid solutions
(GaAs)1-у-z(Ge2)y(ZnSe)z were measured on an ECOPIA setup (Hall Effect Measurement
system HMS-550+AHT55T5). The resulting epitaxial films had n-type conductivity. The
carrier concentration and mobility were ~ 5∙1020 sm-3 and µ - 9.2-11 sm2/(Vs), respectively.
On Fig 4 shows the crystal lattice of a solid solution of molecular substitution (GaAs)1-y-z(Ge2)y(ZnSe)z.
As can be seen from Fig 4, in the crystal lattice of the solid solution there are covalent bonds such as Ga-As,
Ga-Ge, Ga-Se, Zn-Se, Zn-As, Zn-Ge, Ge-Ge, Ge-As, Ge-Se. Since the breaking energies
of such covalent bonds are different, they can contribute to the appearance of the
corresponding peaks in the photosensitivity spectrum of the solid solution.
Fig. 4. Hypothetical crystal lattice of the solid solution (GaAs)1-у-z(Ge2)y(ZnSe)z
The surface of the resulting epitaxial films was examined using an SPM 9700HT (Shimadzu)
atomic force scanning microscope. When examining the surface of the films, nanocrystallites
were detected (Fig 5) with a height of 6.5-7.5 nm. The width at the base of the nanocrystallites was ~120–150
nm (Fig 6). The concentration of nanocrystallites (quantum dots) on the surface of the epitaxial
film was 2.5∙108 sm-2.
Spectral photosensitivity of n-GaAs–n+-(GaAs)1-y-z(Ge2)y(ZnSe)z structures
On Fig 7 shows the dependence of the photosensitivity of the n-GaAs–n+-(GaAs)1-y-z(Ge2)y(ZnSe)z
heterostructure on the photon energy (Eph). It can be seen that the spectral photosensitivity
of the studied structure has a complex character and covers a wide range of photon
energies, from 1.3 to 2.5 eV. In the photon energy range of 1.5–2.4 eV, the sensitivity
is not monotonic; there are subtle rises at Eph = 1.5 eV and 1.9 eV. This is apparently
due to the inhomogeneity of the composition of the solid solution.
Fig. 5. Three-dimensional image of the surface of the epitaxial film (GaAs)1-x-y (Ge2)x(ZnSe)y,
obtained using an atomic force microscope, Image size 5x5 μm2
The molar ratios of the components GaAs (Eg, GaAs = 1.43 eV), Ge (Eg, Ge = 0.67 eV),
and ZnSe (Eg, ZnSe = 2.68 eV) are different over the thickness of the epitaxial film;
accordingly, each sublayer of the solid solution has its own fundamental absorption
region.
Fig. 6. Dimensions of quantum dots on the surface of the solid solution
(GaAs)1-x-y(Ge2)x(ZnSe)y: width - 120-150 nm, height - 6.5-7.5 nm, the distance between
quantum dots is 300-450 nm. In our case, it is determined by the thickness of the
n+-(GaAs)1-y-z (Ge2)y(ZnSe)z epitaxial layer and is ~10 µm. When the diffusion length
of charge carriers is less than the thickness of the separating barrier, then the
electron-hole pairs generated by high-energy photons in the near-surface region of
the structure do not reach the separating barrier and do not participate in the creation
of a photocurrent. Therefore, the sensitivity of the structure in the short-wavelength
region of the radiation spectrum decreases.
Fig. 7. Spectral dependences of the photosensitivity of the n-GaAs-n+(GaAs)1-x-y (Ge2)x(ZnSe)y
structure at 300 K.
4. Conclusion
The physico-technological features of growing a new solid solution of molecular substitution
(GaAs)1-y-z(Ge2)y(ZnSe)z on GaAs (111) substrates from a limited volume of Bi solution-melt
are studied. The optimal thermodynamic conditions for growing single-crystal epitaxial
films of the (GaAs)1-y-z(Ge2)y(ZnSe)z solid solution are determined. The spectral
dependence of the photosensitivity of the n-GaAs-n+(GaAs)1-x-y(Ge2)x(ZnSe)y structure
covers the photon energy range from 1.3 eV to 2.5 eV, with maxima at 1.6 eV, 2.0 eV
and 2.4 eV. It has been found that the (GaAs)1-y-z (Ge2)y(ZnSe)z solid solution has
selective photosensitivity due to the peculiarities of Ge and ZnSe nanocrystals in
the epitaxial layer, with different ionization energies of the corresponding molecules.
Studying the patterns of formation of an ordered set of nanosized crystals in the
bulk or on the surface of a (GaAs)1-y-z (Ge2)y(ZnSe)z solid solution makes it possible
to control the sizes of nanocrystals, manufacture devices operating on the basis of
the size effect, and expand the range of spectral sensitivity of this material. Solid
solutions (GaAs)1-y-z(Ge2)y(ZnSe)z can be used as a photoactive material for a selective
photodetector operating in the near-IR and visible regions of the radiation spectrum.
Acknowledgements
Hello dear editorial members of The Transactions of the Korean Institute of Electrical
Engineers (KIEE)! Thank you for taking the time to review our article on Investigation
of the Spectral Photosensitivity of nGaAs-n+(GaAs)1-x-y(Ge2)x(ZnSe)y Heterostructure
Obtained from Bi Solution-Melt! We would also like to thank the reviewers who have
reviewed our article. We are pleased that the reviewers of the article, in turn, gave
a fair and accurate assessment. We hope to co-publish more scientific articles with
your journal in the future. We also wish the members of the magazine's editorial board
and the magazine's activities good luck! In the future, we wish to increase the ranking
of the magazine in the Scopus database, and in this regard, we, as the author, will
promote your magazine and the published scientific articles more widely among the
scientists of Uzbekistan.
Sincerely, the author, Shavkat Ismailov!
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저자소개
Ismailov Shavkat Kuzievich
In 1990 he graduated from the Faculty of Physics of the National University of Uzbekistan
with the specialty Theoretical Physics. Since 1990, he worked at the Physico-Technical
Institute of the Academy of Sciences of Uzbekistan, and since 1992 at Urgench State
University. In 2007, he defended his dissertation on the topic “Growth and research
of electronic and optical properties of semiconductor solid solutions” and received
a Doctor of Science degree in the specialty “Physics of Semiconductors and Dielectrics”.
Until 2016, he worked as an associate professor at the Department of Physics at Urgench
State University. Since 2016, he has been the head of the Department of Telecommunication
Engineering at the Urgench branch of Tashkent University of Information Technologies.
Under the project ERASMUS- EDU-2022-101083224 within the framework of the ERASMUS+
program of the European Union, he completed an internship at the Belgian universities
of Gent and VRIJE of Brussels (VUB), and the Polytechnic University of Turin (Politeknico
di Torino).
He is the author or co-author of more than 60 peer-reviewed journal and conference
articles, 2 monographs and 3 textbooks, and 6 scientific articles indexed in the Scopus
(Elsevier) database. He can be contacted at ishavkat6819@gmail.com
In 1984 he received the degree of Doctor of Physical and Mathematical Sciences. He
is a professor at the laboratory “Growth of Semiconductor Crystals” at the Physico-Technical
Institute of the Academy of Sciences of the Republic of Uzbekistan. Laureate of the
State Prize of the Republic of Uzbekistan "On awarding state prizes of the Republic
of Uzbekistan in 2007 in the field of science and technology, literature, art, and
architecture" for internationally recognized fundamental research "New semiconductor
solid solutions and impurity effects of semiconductors".He created a scientific direction
on the physicochemical basis of the synthesis technology for new semiconductor solid
solutions IV1-xIVx, (IV2)1-x(A3B5)x, (IV2)1-x(A2B6)x, (IV2)1-x-y(A3B5)x (A2B6)y on
silicon substrates, and their homo- and heterostructures. For the first time he detected
impurity photovoltaic, thermal-voltaic, phototemplotvoltaic effects, as well as the
effect of two-color radiation in a single crystal. Polycrystalline silicon with a
purity of 99.9 atomic% was obtained by an ecologically clean method in a small solar
furnace by repeated remelting of metallurgical silicon in the open air.Scientific
interests: interaction of impurities in diamond-like semiconductors and physical bases
for growing silicon, gallium arsenide, aluminum-gallium arsenide, high-resistance,
homogeneous and graded band gap, new solid solutions IV1-xIVx, (IV2)1-x(A3B5)x, (IV2)1-x
(A2B6)x, (IV2)1-x-y(A3B5)x (A2B6)y on silicon substrates, as well as homo- and heterostructures
based on them. Published 2 monographs, 1 collection of articles, more than 277 scientific
articles and 36 patents. He can be contacted at amin @uzsci.net
Usmonov Shukrullo Negmatovich
In 1989 he graduated from the Faculty of Physics of St. Petersburg State University
with a degree in Radiophysics. In 1994, he graduated from doctoral studies at the
Physico-Technical Institute of the Academy of Sciences of Uzbekistan with a specialty
in “Physics of Semiconductors and Dielectrics” and received the degree of Candidate
of Physical and Mathematical Sciences (PhD); in 2018, he received the degree of Doctor
of Physical and Mathematical Sciences (DSc) with a degree in Semiconductor Physics.
In 2009, with a degree in Semiconductor Physics, he received a diploma of “Senior
Researcher” from the Academy of Sciences of Uzbekistan. Currently he is the head of
the laboratory “Growth of Semiconductor Crystals” at the Physico-Technical Institute
of the Academy of Sciences of Uzbekistan. Under his leadership, 2 candidates of science
(PhD) were trained. His research interests include photoelectric, thermovoltaic and
luminescent effects in semiconductor materials, the interaction and distribution of
chemical elements and compounds in multicomponent single- and two-phase systems in
relation to the current needs of semiconductor materials science and solid- state
electronics, as well as the technology of epitaxial films of two and multicomponent
semiconductor solid solutions elementary semiconductors and binary compounds III-V
and II-VI. He is a member of the editorial board of the international scientific journal
Applied Solar Energy, author or co-author of more than 230 articles published in peer-
reviewed scientific journals and scientific conference proceedings, 1 patent for an
invention, 1 monograph, 3 study guides and 2 textbooks, including 50 indexed scientific
articles in the Scopus database (Elsevier). He can be contacted at shukrullousmonov66@gmail.com.
Saparov Dadajan Valixanovich
He graduated from the Tashkent State Pedagogical Institute named after Nizami in1983.
From 1986 to present, he has been working in the Physical-Technical Institute of the
Academy of Sciences of the Republic of Uzbekistan. In 2020, he received his PhD on
the growth of epitaxial GaSb and GaP films on Si substrates from the liquid phase.
Currently, he is a senior researcher at the laboratory “Growth of Semiconductor Crystals”
at the Physical- Technical Institute of the Academy of Sciences of the Republic of
Uzbekistan and is engaged in growing epitaxial films of various semiconductor solid
solutions on silicon substrates from a melt solution. He can be contacted at dada@uzsci.net
Eshonkhojaev Dilmurod Odilovich
In 1987-1992, he graduated from Tashkent State Technical University, majoring in "engineer-
mechanics in the field of aircraft construction. In 1993-1994 he worked as an engineer
designer at the Andijonmash plant. In 1994-1997 he was the chief customs committee
of the State Tax Committee, Andijan region worked as an inspector in the customs service,
and in 1999-2012, he worked as the head of the department for spiritual and educational
affairs in the scientific and educational center in the form of a limited liability
company for youth development in Andijan. In 2012-2014, he worked as a leading specialist
in the executive committee of the Andijan regional council of the National Democratic
Party of Uzbekistan. From 2014 to now, he has been an assistant at the Andijan Institute
of Mechanical Engineering. He can be contacted at eshonxojayevdilmurod 34@gmail.com
In 1994 she graduated from the Faculty of Physics of Tashkent State University. That
same year, he joined Urgench State University as a research intern. From 1995 to 2001
she worked as a teacher at the Department of Physics at Urgench State University,
and from 2001 to 2017 as a senior teacher. In 2017- 2020 he studied at Urgench State
University in the direction of “04/01/10-Physics of Semiconductors” in doctoral studies.
On May 22, 2021, at a meeting of the Academic Council under number DSс.03/30.12.2019.FM/T.01.12
at the Research Institute of Semiconductor Physics and Microelectronics of the National
University of Uzbekistan on the topic “Narrow- gap solid solutions Gе1- xSnх, (InSb)1-x
(Sn2)x and their photoelectric properties” defended her dissertation and received
a PhD in physics and mathematics. From 2021 to the present, he has been working as
an associate professor at the Department of Physics at Urgench State University. Umida
Asatova is the author of about 40 scientific works, including 15 articles in scientific
journals, 25 theses at international and republican scientific and practical conferences.
In 2022 she published a monograph on the topic “Physics and technology for producing
solid solutions of narrow-gap semiconductors” and in 2023 a textbook “Contact phenomena
in semiconductors”.
Umida Asatova worked from January 03, 2018 to December 31, 2018 in the state grant
project No. ОТ-Ф2-65 on the topic “Study of the laws of scattering of low-energy ions
on the surface of semiconductor single crystals of type AIIIBV,” and from January
05, 2022 to 31 December 2022 in the project of the state grant UZB-Ind-2021-88 on
the topic “Research of hydrophobic and superhydrophobic materials using nanostructures.”
Umida Asatova is a participant in the scientific seminar PhD.03/30.09.2020.FM.55.04
in the specialty “01.04.04 – Physical Electronics”, opened at Urgench State University
and works as the secretary of the scientific seminar PhD.03/29.12.2022.FM.55.07 on
specialty “04/ 01/11 – Laser physics”She can be contacted at umida72@rambler.ru
Bobojanov Sukhrob Gayratovich
received his BS degree in Telecommunication Engineering from the Urgench branch of
Tashkent University of Information Technologies, Uzbekistan, in 2015. He received
his MS degree in Telecommunication Technologies from Tashkent University of Information
Technologies named after Muhammad al-Khwarizmi, Uzbekistan, in 2017. From 2017 to
2018, he worked as an engineer in the Department of Technical Coordination and Support
of State Events at Urgench Branch of "Uzbektelecom" JSC. From 2018 to 2020, he worked
as an assistant teacher in the Department of Telecommunication Engineering at Urgench
Branch of Tashkent University of Information Technologies named after Muhammad al-Khwarizmi
in Urgench, Uzbekistan. He received his Ph.D. degree in Software Engineering from
Kumoh National Institute of Technology, Gumi, South Korea in 2024. He can be contacted
at w.suxrob.w@ gmail.com.