Volume 02 Issue 09-2022
22
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
02
I
SSUE
09
Pages:
22-25
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
OCLC
–
1121105677
METADATA
IF
–
5.582
Publisher:
Oscar Publishing Services
Servi
ABSTRACT
Cadmium telluride films are grown on single-crystal silicon substrates by vacuum deposition in a quasi-closed volume.
CdTe films were studied by atomic force and scanning electron microscopy.
KEYWORDS
Cadmium tellurium, silicon, films, composition, structure, temperature.
INTRODUCTION
Synthesis of polycrystalline films based on CdTe with
the possibility of controlling, activating or inhibiting
electronic processes at the crystallite boundary by
technological methods and studying their structure
Research Article
STRUCTURAL STUDIES OF FILMS CADMIUM TELLURIDE GROWN ON
SILICON SUBSTRATES
Submission Date:
August 30, 2022,
Accepted Date:
September 06, 2022,
Published Date:
September 20, 2022
Crossref doi:
https://doi.org/10.37547/ajast/Volume02Issue09-04
Sh.B. Utamuraova
Institute of Semiconductor Physics and Microelectronics at NUUz, Tashkent, Uzbekistan
N.A. Turgunov
Institute of Semiconductor Physics and Microelectronics at NUUz, Tashkent, Uzbekistan
S.A. Muzafarova
Institute of Semiconductor Physics and Microelectronics at NUUz, Tashkent, Uzbekistan
K.M. Fayzullaev
Institute of Semiconductor Physics and Microelectronics at NUUz, Tashkent, Uzbekistan
Journal
Website:
https://theusajournals.
com/index.php/ajast
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 02 Issue 09-2022
23
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
02
I
SSUE
09
Pages:
22-25
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
OCLC
–
1121105677
METADATA
IF
–
5.582
Publisher:
Oscar Publishing Services
Servi
and electro-optical properties are important and
relevant not only in scientific but also in practical terms.
In addition, in this regard, polycrystalline structures
grown on single-crystal silicon substrates are of great
interest recently.
The determining factor affecting the structure and
perfection in the process of growth of a CdTe binary
compound
with
given
electrophysical
and
photoelectric parameters is the pressure of Cd and Te
vapors, respectively, the source temperature, the
substrate temperature, and the cooling temperature.
The advantages of this method are the purity of the
deposited material under high vacuum, the uniformity
of the synthesized film; versatility. Films are deposited
on metals, alloys, semiconductors, and dielectrics with
the possibility of using masks to fabricate layers with a
given configuration.
Experiment
Polycrystalline films of cadmium telluride were
obtained on single-crystal silicon substrates by vacuum
deposition in a quasi-closed volume [1]. In many cases,
a CdTe film on Si grows polycrystalline [2–5]; in
addition, during the chemical deposition of CdTe, some
components react with the silicon substrate to form
the Si2Te3 silicon sesquitelluride phase [6].
The determining factor affecting the structure and
perfection in the process of growth of a CdTe binary
compound
with
given
electrophysical
and
photoelectric parameters is the pressure of Cd and Te
vapors, respectively, the source temperature, the
substrate temperature, and the cooling temperature.
The advantages of this method are the purity of the
deposited material under high vacuum, the uniformity
of the synthesized film; versatility. Films are deposited
on metals, alloys, semiconductors, and dielectrics with
the possibility of using masks to fabricate layers with a
given configuration.
Cadmium
telluride
(CdTe)
is
a
direct-gap
semiconductor of the A2B6 group with a band gap of
1.49 eV [7]. In recent years, interest in CdTe has
noticeably increased due to its widespread use in the
creation of solar batteries, ionizing radiation detectors,
and photodetectors [7,8]. Due to the optimal
scattering, electrical and optical characteristics,
cadmium telluride is effective for the manufacture of
photoresistors, solar cells, schematic analysis of
radioactivity, elemental infrared optics, etc. It is widely
used in optical and electronic technology. Silicon (Si) is
often used as a substrate.
In the process of optimizing the growth of CdTe films,
single-crystal silicon substrates underwent standard
chemical treatment to remove the oxide layer and
passivate the surface. The initial thick oxide was
removed from the substrate surface in concentrated
hydrofluoric acid HF. Then the substrate was placed in
a hot solution of NH40H:H202:H20 in a ratio of 1:4:20.
In this case, a thin oxide layer was formed, which was
then removed in a 0.5% aqueous solution of HF. After
each operation, rinsing in deionized water was carried
out. As a result of such treatment, the surface became
passivated (hydrogenated) [4]. The samples were
attached to the carrier with presser feet in a laboratory
fume hood. Exposure to air did not exceed 10-15
minutes.
After preliminary heating for 4 hours at a temperature
of 160°C, the samples were annealed at T=550°C for 15
min to remove the passivating layer. The Si-CdTe
heterosystem is highly mismatched both in terms of
the crystal lattice parameters of the substrate and film
(at room temperature; a& = 0.5431 nm, ds<Ps = 0.6477
nm) and in polarity and valence of the film and
substrate materials. Therefore, the main part of the
Volume 02 Issue 09-2022
24
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
02
I
SSUE
09
Pages:
22-25
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
OCLC
–
1121105677
METADATA
IF
–
5.582
Publisher:
Oscar Publishing Services
Servi
defects in the creation of the Si - CdTe structure is laid
at the heterointerface. At present, the main methods
for reducing the density of defects at the Si±CdTe
heterointerface are pre-epitaxial modification of the
surface structure of the Si substrate with elements of
groups V and VI. For example, the authors of [1]
showed that pretreatment of the silicon surface with
arsenic and the use of algo-layer epitaxy at the initial
stages of buffer layer growth can significantly improve
the structural perfection of the CdTe layer.
It was found that the process of tellurium adsorption
on the silicon surface can be divided into stages: at
sample temperatures below 170 °C, a polycrystalline
CdTe film grows, this process is not limited in any way,
and a polycrystalline CdTe film of any thickness can be
grown. In the sample temperature range above 170–
350°C, regardless of the flux density and exposure
time, the number of tellurium atoms from CdTe on the
silicon surface does not exceed 20% of the number of
atoms in the volume under study. If the sample has a
temperature of more than 350°C, tellurium is not
detected on the surface and no superstructural
rearrangements are observed.
a)
b)
Fig. 1. SEM image of the surface of a CdTe film on a ground (a) and polished (b) Si
substrate.
The resulting Si - CdTe heterostructures, where CdTe
films grown by sputtering in a quasi-closed volume on
single-crystal silicon substrates, were studied by
atomic force and scanning electron microscopy (Fig. 1).
The roughness of Si films varies in the range of 34–87
nm with an average grain size in the range of 2.5–5 μm.
The film grown on it has a large crystallinity, pure, the
size of which varies from 3.5 to 4 microns. In contrast
to the film on a polished surface, the roughness of
silicon increased on a polished surface has increased
significantly and is 87.5 nm. X-ray diffraction analysis
showed that the polycrystalline
structure of a semi-thin CdTe film thickness varies
within 150–200 µm.
The preparation of films with different morphological
surfaces and the possibility of growing crystalline films
with a grain size of 2.5 to 5 μm and a thickness of 34.07
to 87.49 nm on a silicon substrate are shown. The
composition of the film grown on the Si substrate
includes: Cd - 50.44 % atoms, Te - 48.75 % atoms and
they contain up to 0.82 % aluminium.
Volume 02 Issue 09-2022
25
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
02
I
SSUE
09
Pages:
22-25
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
OCLC
–
1121105677
METADATA
IF
–
5.582
Publisher:
Oscar Publishing Services
Servi
CONCLUSION
In the future, the study of the properties of Si-CdTe
heterostructures and its Si2Te3 transition layer, the
effect on the electrical and optical properties of the Si-
CdTe heterosystem and other photosensitive devices
based on them for a wide range of applications, creates
great scientific and practical interest.
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Feng K. A., Hu X.M., Lin Z., Xing Y.R. The structures
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Si(113)
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Muzafarova S.A. Study of photosensitive SDS
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Abdulin V.V. Structure and properties of CdTe films
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Belyaev A.P., Rubets V.P., Nuzhdin M.Yu. Electrical
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