Clusters of nickel atoms and controlling their state in the silicon lattice
The paper reports that using the IR-spectroscopy technique, it has been revealed that nickel atoms in the silicon lattice are gathered in clusters, i.e., the phenomenon of self-assembly takes place. The concentration and dimension of the clusters are mainly defined by the temperature of diffusion an...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
2018
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| Cite this: | Clusters of nickel atoms and controlling their state in the silicon lattice / M.K. Bakhadyrkhanov, K.A. Ismailov, B.K. Ismaylov, Z.M. Saparniyazova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 392-396. — Бібліогр.: 8 назв. — англ. |
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| author | Bakhadyrkhanov, M.K. Ismailov, K.A. Ismaylov, B.K. Saparniyazova, Z.M. |
| author_facet | Bakhadyrkhanov, M.K. Ismailov, K.A. Ismaylov, B.K. Saparniyazova, Z.M. |
| citation_txt | Clusters of nickel atoms and controlling their state in the silicon lattice / M.K. Bakhadyrkhanov, K.A. Ismailov, B.K. Ismaylov, Z.M. Saparniyazova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 392-396. — Бібліогр.: 8 назв. — англ. |
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| description | The paper reports that using the IR-spectroscopy technique, it has been revealed that nickel atoms in the silicon lattice are gathered in clusters, i.e., the phenomenon of self-assembly takes place. The concentration and dimension of the clusters are mainly defined by the temperature of diffusion and the cooling rate. The composition of clusters of nickel impurity atoms was determined. It was shown that in the process of thermal annealing within the temperature range 650…900 °С there is a significant change in the state, concentration, and size of clusters. Thermal annealing at the above temperatures, 650…900 °С leads to ordering the clusters, that is, self-assembly of cluster blocks, as well as clusters of a loop shape that includes several dozens of clusters. A diffusion technique to form and order clusters of nickel atoms in silicon has been suggested.
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ISSN 1560-8034, 1605-6582 (On-line), SPQEO, 2018. V. 21, N 4. P. 392-396.
© 2018, V. Lashkaryov Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
392
Hetero- and low-dimensional structures
Clusters of nickel atoms and controlling their state in silicon lattice
M.K. Bakhadyrkhanov, K.A. Ismailov, B.K. Ismaylov, Z.M. Saparniyazova
Tashkent State Technical University, Department of Digital Electronics and Microelectronics
Uzbekistan, Tashkent, Universitetskaya 2, 100095
E-mail i.bairam@bk.ru
Abstract. The paper reports that using IR-spectroscopy technique, it has been revealed that
nickel atoms in the silicon lattice are gathered in clusters, i.e., the phenomenon of self-
assembly takes place. The concentration and dimension of the clusters are mainly defined
by the temperature of diffusion and the cooling rate. The composition of clusters of nickel
impurity atoms was determined. It was shown that in the process of thermal annealing
within the temperature range 650…900 °С there is a significant change in the state,
concentration and size of clusters. Thermal annealing at the above temperatures
650…900 °С leads to ordering the clusters that is, self-assembly of cluster blocks, as well
as clusters of a loop shape that includes several dozens of clusters. A diffusion technique to
form and order clusters of nickel atoms in silicon has been suggested.
Keywords: silicon lattice, cluster, nickel atom, cluster loop, annealing, diffusion, self-
assembly, nanostructure, bandgap, Schottky microbarriers.
doi: https://doi.org/10.15407/spqeo21.04.392
PACS 64.75.Qr, 71.62.uf
Manuscript received 18.10.18; revised version received 15.11.18; accepted for publication
29.11.18; published online 03.12.18.
1. Introduction
Impurity clustering in the semiconductor lattice is of
great scientific and practical interest. This might occur
not only owing to the possibility to alter the fundamental
parameters of semiconductors [1], but also to the chances
of obtaining a specific variety of semiconductors, i.e.,
bulk nanostructured semiconductor materials [2].
As compared to conventional semiconductor
materials with nanostructures, the bulk nanostructured
semiconductors can likely demonstrate much greater
functionality [3].
From this viewpoint, nickel atoms in the silicon
lattice are of great interest, because they are expected to
behave differently than other impurity atoms that create
deep energy levels in Si bandgap. This is primarily
caused by the sufficiently high solubility (N ~ 1018 cm–3),
which is 1.5…2 times higher than that of impurity atoms
of II and VI groups as well as of the transition metals
one. Another major difference is the anomalously high
diffusion coefficient (D ~ 10–5 cm2/s at T = 1200 °C) of
Ni in silicon [4-5]. It’s worth mentioning that only a
minuscule fraction of the doped nickel atoms happen to
be in electrically active state, i.e., only those atoms that
are located at the lattice sites. Atoms of nickel create two
acceptor levels in the bandgap of silicon: E1 =
EV + 0.2 eV, E2 = EC – 0.4 eV [6], the concentration of
which tends to be NS ~ 4·1014 cm–3 at 1250 °C. The lion’s
share of the embedded atoms (99.99%) tends to be in
interstitial positions in the silicon lattice and in
electrically neutral state, which serve as a stimulating
factor for assembly of clusters of nickel impurity atoms
in the lattice [7].
Another advantage of using these impurity atoms is
that the diffusion of nickel can be realized under ambient
conditions in air (without vacuum), which allows the
alloying of silicon wafers of various diameters. This not
only creates cost-effective technological doping
conditions, but also allows obtaining samples with fairly
homogeneous and reproducible parameters.
2. Technology and technique of research
A single-crystalline n-type silicon sample with the
resistivity 40…60 Ohm·cm was chosen as a starting
material for diffusion of nickel atoms. The concentration
of oxygen was NO2 ~ 4·1017 cm-3, whereas the density of
dislocations was S ~ 4·103 cm2. The diffusion of nickel
was carried out from 1 µm-thick pure metallic layer of
nickel deposited on the surface of a silicon wafer (60 mm
in diameter and 1 mm thick) under conditions of a
sufficiently high vacuum P ~ 10–6 atm. Diffusion was
carried out in the air within the range of T =
1050…1250 °С for t = 0.5…5 hours. After diffusion, the
samples were removed from the furnace and cooled off in
air. Shortly thereafter, silicon wafers doped with Ni were
cut into samples with dimensions 1×4×10 mm.
SPQEO, 2018. V. 21, N 4. P. 392-396.
Bakhadyrkhanov M.K., Ismailov K.A., Ismaylov B.K., Saparniyazova Z.M. Clusters of nickel atoms and controlling …
393
Fig. 1. (a) Homogeneous distribution of clusters. (b) Reference
sample without Ni clusters.
Having done mechanical and chemical processing,
the electro-physical parameters of the samples were
measured by the Hall effect technique. Eventually, it was
revealed that the electro-physical parameters of all the
samples under investigation practically were the same
and did not significantly differ from each other, which is
evident of homogeneity of silicon wafer doping.
It was also revealed that the electro-physical
parameters of the investigated samples were practically
similar and did not depend on diffusion time (t =
0.5…5 h) but on the diffusion temperature of annealing,
which confirms the sufficiently high diffusion rate of Ni
atoms in silicon [4].
All the samples, after doping with nickel at the
temperature T = 1250 °C, had a reversed type
conductivity type, i.e., became of p-type with the
resistivity ρ ~ (4…5)·103 Ohm·cm. Being based on the
temperature dependence inherent to the Hall coefficient,
it was determined that the concentration of electro-active
atoms of nickel turned out to be N = (1.5…2)·1014 cm–3.
3. Results and discussion
The process of formation and dynamics of changes in the
state of clusters from nickel atoms in silicon lattice were
studied using the infrared microscope MIK-5, and also
by using the X-ray diffraction analysis (“Panalytical
Empyrean” diffractometer λ = 1.5418 Å (CuK (alpha)
RADIATION) – copper tube.
The samples after having been mechanically and
chemically treated were polished (both sides) for optical
investigation under microscope, and the results were
processed with a computer. The results of IR microscope
studies showed that in the samples doped with nickel at
the temperature T = 1250 °C and after diffusion
annealing, almost uniform distribution of dark dots both
on the surface and in the near-surface region may be
observed, whereas the size of them was approximately
d = (1…2) µm and density S = (1,5…2)·107 cm2
(Fig. 1a).
Reference samples annealed under the same
conditions, but without nickel atoms, were sufficiently
transparent in the infra-red spectrum, and no such dark
dots were found in them (Fig. 1b). The nature of dark
dots in Si samples doped with nickel was further
investigated by X-ray diffraction analysis.
Fig. 2. Content analysis of clusters consisting of impurity nickel
atoms (picture depict. SEM EVO-MA10).
As the results of our investigations show (Fig. 2),
the dots consists of nickel (7-8%), oxygen (8%), silicon
(71-72%), which means the clusters represent array of
solid solutions containing both Ni and oxygen atoms, and
every tenth atom is either atom of nickel or oxygen. The
approximate dimension of such clusters is about V =
2·2·2 µm3 = 8·10–12 cm3, they can contain about 2·109
atoms, of which about 2·108 are atoms of Ni, whereas the
bulk of the atoms in them is represented by silicon atoms
located in crystal lattice sites.
The Ni atoms are mainly in the form of electrically
neutral atoms (3d
104s
0), and the distance between them is
d = 5…6 nm. Therefore, it can be assumed that in the
clusters, nickel atoms can form a face-centered cubic
sublattice [1].
Thus, based on these results, one can assume that
the dark dots represent microclusters enriched with atoms
of nickel. To confirm the idea that such clusters occur
over the entire bulk crystal, and not only at the surface,
we polished the investigated samples and remove 50 µm
of layer from both sides, until the samples were reduced
to half in size. After the each grinding step, the samples
were polished and examined under IR microscope in
identical technological conditions. The results of the
study apparently confirmed that the clusters appear to be
practically uniformly distributed throughout the entire
crystal bulk, and their dimensions and densities also did
not differ significantly.
The concentration of clusters was about N =
5·1011…1012 cm–3, which means that the clusters were
practically uniformly distributed throughout the entire
bulk of material. The results of the study showed that if
conditions of cooling of the samples after the diffusion
annealing are maintained at T = 1250…1100 °C, then,
depending on the diffusion temperature, their
concentration would vary within the range N =
4.5·1012 cm–3 down to 6.5·1011 cm–3. It was revealed that
the size and concentration of clusters essentially depend
on the cooling rate of the samples after the diffusion
annealing has ended. One can reasonably assume that by
varying the diffusion and cooling rates, one can create
nickel clusters of different sizes in the wide range.
а) b)
SPQEO, 2018. V. 21, N 4. P. 392-396.
Bakhadyrkhanov M.K., Ismailov K.A., Ismaylov B.K., Saparniyazova Z.M. Clusters of nickel atoms and controlling …
394
Fig. 3. Dynamics of changes in the size of clusters after thermal
annealing at: 1000 (a), 900 (b), and 800 °С (c).
The samples were afterwards annealed in the
temperature range of 1100…650 °C for 2 to 5 hours.
The prime concern behind this procedure was to
determine first of all the stability of clusters at lower
annealing temperatures, and secondly to establish the
functional correlation between the parameters of the
clusters as a function of temperature and duration of
thermal annealing, since the temperature of thermal
annealing changes the super saturation of the Si-Ni
solid solution.
The results of the research showed that the thermal
annealing causes enlargement of clusters, i.e., their size
increases, and their density decreases accordingly. This
process persist to temperature annealing at T = 750 °C.
The dynamics of changes in clusters’ dimensions is
shown in Fig. 3. As can be seen, in this case clusters’
sizes reach 3…5 µm, and the uniform distribution is well
preserved still. The increase in the size of clusters, as
well as the appearance of transparent areas in the samples
during thermal annealing, suggests that it witnesses the
reunion of small clusters with each other.
As a result, in the course of thermal annealing of
these samples at T = 750 °C for t = 2…5 hours, very
interesting physical phenomena were observed, that is,
the clusters started to assemble in order, i.e., chain of
ordered clusters of nickel impurity atoms is formed in
silicon lattice (Fig. 4a). It is established that the effect of
ordering the clusters occurs throughout the bulk across
different crystallographic directions. As the time of
thermal annealing increases, this process goes on, and the
length of the chain of clusters increases substantially.
The dynamics of ordering of clusters is shown in Figs.
4a–4d.
As the annealing time at T = 750 °С increases, more
and more clusters participate in the process of chain
formation, and even larger transparent areas appear in the
samples. The annealing for more than t > 9 hours did not
lead to a significant change in ordering the clusters. This
proves that almost all clusters somehow manage to
participate in the ordering process.
It was ascertained that the length of cluster chains
can reach from 150…200 up to 350…400 µm, and the
number of clusters in the chain varies from 20 to 50, the
distance between clusters in these chains can be from 0.5
to 1.5 µm. The different sharpness of the cluster chains
found in the samples (Fig. 4d) suggests that the cluster
chains are located in different depth profiles of the
sample.
These results enabled us to assume that ordering the
clusters occurs throughout the entire bulk of the crystal.
The second even more interesting phenomenon is
formation of the so-called “cluster loops”, in some
samples during thermal annealing at T = 75…700 °С. As
the time of annealing increases, the growth of the cluster
loops becomes more and more transparent, and more and
more clusters seem to participate in this process (Fig. 5).
As the time of thermal annealing increases, the
number of clusters in the loop remains practically
unchanged, but the density of the loop grows. It was
found that the shape of the cluster loops is basically close
to hexahedrons with a diameter d = 10…20 µm, whereas
the number of clusters in them ranges from 5 to 10.
The results of this investigation give sufficient
ground to assert that in the silicon lattice the so-called
“self-assembly” of the clustering of nickel atoms takes
place. Meanwhile, the size and density of the clusters
depend mainly on the cooling rate and the diffusion
temperature. It can be assumed that rapid cooling leads to
formation of clusters that are several nanometers in size,
and their concentrations can reach N ~ 1013÷1014 cm–3,
whereas the number of atoms in these clusters can reach
n = 103÷104.
а)
b)
c)
SPQEO, 2018. V. 21, N 4. P. 392-396.
Bakhadyrkhanov M.K., Ismailov K.A., Ismaylov B.K., Saparniyazova Z.M. Clusters of nickel atoms and controlling …
395
Fig. 4. Dynamics of ordering the clusters of nickel atoms in the
silicon lattice at 750 °C: a) t = 3 hours, b) 5, c) 7, and d) 9.
Fig. 5. Dynamics of formation of a cluster loop in the samples
after thermal annealing at the temperature T = 750 °C: a) t = 3
hours, b) 6 hours, and c) 9 hours.
The availability of more advanced equipment could
allow us to observe evolution of nanoscale clusters and
establish the law of change in their sizes and
concentration as functions of the cooling rate after
diffusion annealing. The investigative results obtained
make it possible to assert that by varying the temperature
of diffusion and cooling rate, it would be possible to
obtain bulk nano- and microstructured silicon with nano-
and microclusters of nickel atoms with pre-determined
dimensions and concentrations.
The temperature variation and the additional
annealing time variation at lower temperatures allows to
а)
b)
c)
d)
а)
b)
c)
SPQEO, 2018. V. 21, N 4. P. 392-396.
Bakhadyrkhanov M.K., Ismailov K.A., Ismaylov B.K., Saparniyazova Z.M. Clusters of nickel atoms and controlling …
396
control the state of clusters, that is, formation of cluster
chains and loops with the required parameters. Formation
of clustered chains and cluster loops is practically a new
phenomenon and its physical nature is yet to be
understood.
Formation of cluster chains and loops substantially
increase the functionality of materials. One could
develop nano- and microscale superlattices and ideal
nano- and microbarriers of Schottky as well as surface
state-free heterojunctions, as well as nano- and
microdimensional variband structures, and finally, such
materials could be availed in creation of more efficient
solar cells with a wider spectral range.
A few words about the strengthening and formation
of cluster chains and cluster loops. The obtained results
allow us to assume that in this case the diffusion of
whole clusters takes place practically at the same
diffusion rate as that of nickel atoms in silicon, and the
process of lump diffusion is well synchronized.
This process can only happen, if the nickel atoms
participating in the clusters are in interstitial sites and
create a certain type of sublattice inside the basic silicon
matrix. These assumptions require more careful
investigations, and further experimental studies are to be
done using modern research methods. The study of
electrical, optical, photoelectric, as well as deformation
properties of silicon with clusters of nickel atoms, allows
us to discover new physical features of a new material.
4. Conclusion
In conclusion, it can be said that silicon doped with
nickel atoms could be of great interest, as it represents a
novel material characterized by boosted functionality
that, in turn, would allow enhancing the modern
optoelectronics, photonics and photovoltaics, as well as
nanoelectronics. And most importantly, based on a fairly
simple and cheap technology, it would be possible to
obtain bulk nano- and microstructured materials based on
the basic material of modern electronics [8-9].
References
1. Mil’vidskii M.G., Chaldyshev V.V. Nanometer-size
atomic clusters in semiconductors – a new approach
to tailoring material properties Semiconductors.
1998. 32, Issue 5. P. 457–465.
2. Borisenko V.E., Vorob’ieva A.I., Daniliuk A.L.,
Utkina E.A. Nanoelectronics: Theory and Practice.
Handbook. 3-rd ed. Moscow: Binom. Laboratoriya
znanii, 2013 (in Russian).
3. Poole Ch.P., Jr., Owens F.J. Introduction to
Nanotechnology. Wiley-Interscience, 2003.
4. Milnes A.G. Deep Impurities in Semiconductors.
New York, Wiley, 1973.
5. Boltaks B.I. Diffusion and Point Defects in
Semiconductors. Leningrad, Nauka, 1972 (in
Russian).
6. Abdurakhmanov K.P., Kulikov G.S., Lebedev A.A.,
Utamuradova Sh.B., Yusupova Sh.A. Investigation
of the behavior of manganese and nickel impurities
in diffusion doping of silicon. Fizika tekhnika
poluprovodnikov. 1991. 25, Issue 6. P. 1075–1078
(in Russian).
7. Abdurakhmanov B.A., Bakhadirkhanov M.K.,
Saitov E.B. et al. Formation of clusters of impurity
atoms of nickel in silicon and controlling their
parameters. Nanoscience and Nanotechnology.
2014. 4, No. 2. P. 29–32.
doi:10.5923/j.nn.20140402.01.
8. Bakhadyrkhanov M.K., Iliev Kh.M., Ayupov K.S.,
Abdurakhmonov B.A., Krivenko P.Yu.,
Kholmukhamedov R.L. Self-organization of nickel
atoms in silicon. Inorganic Materials. 2011. 47,
No 9. P. 962–964.
https://doi.org/10.1134/S0020168511090020.
Authors and CV
Bakhadyrkhanov Muhammad
Kabir Saydkhanovich. Doctor of
Physical-and- Mathematical Sciences,
Professor, Academician of Tashkent
Technical University, Uzbekistan,
Tashkent. Author of more than 350
articles, and among them: 25 patents,
10 monographs, 15 textbooks and educational manuals.
Tashkent State Technical University
Ismailov Kanatbay Abdreymovich.
Doctor of Phisical-and-Mathematical
Sciences, Professor, Head of
Semiconductor Physics Department
of Karakalpak State University,
Uzbekistan, Nukus. Autor of more
than 300 articles, and among them: 4
patents, 1 monograph, 10 textbooks and educational-
methodological manuals.
Tashkent State Technical University
Ismaylov Bayrambay
Kanatbavevich. Currently he is a
post-graduate student at the Physical-
Mathematical faculty of Karakalpak
State University. Author of 10
scientific publications. Research
interests include the use of
nanostructured silicon for applications
in efficient solar cells.
Tashkent State Technical University
Saparniyazova Zlikha Maksetovna.
Assistant-Teacher of Karakalpak
State University. Author of 30
scientific publications. Area of
scientific interests comprises
interaction of atomic clusters of
Nickel and Manganese with lattice
defects in Silicon.
Tashkent State Technical University
|
| id | nasplib_isofts_kiev_ua-123456789-215321 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1560-8034 |
| language | English |
| last_indexed | 2026-03-23T18:47:41Z |
| publishDate | 2018 |
| publisher | Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
| record_format | dspace |
| spelling | Bakhadyrkhanov, M.K. Ismailov, K.A. Ismaylov, B.K. Saparniyazova, Z.M. 2026-03-12T08:53:42Z 2018 Clusters of nickel atoms and controlling their state in the silicon lattice / M.K. Bakhadyrkhanov, K.A. Ismailov, B.K. Ismaylov, Z.M. Saparniyazova // Semiconductor Physics Quantum Electronics & Optoelectronics. — 2018. — Т. 21, № 4. — С. 392-396. — Бібліогр.: 8 назв. — англ. 1560-8034 PACS: 64.75.Qr, 71.62.uf https://nasplib.isofts.kiev.ua/handle/123456789/215321 https://doi.org/10.15407/spqeo21.04.392 The paper reports that using the IR-spectroscopy technique, it has been revealed that nickel atoms in the silicon lattice are gathered in clusters, i.e., the phenomenon of self-assembly takes place. The concentration and dimension of the clusters are mainly defined by the temperature of diffusion and the cooling rate. The composition of clusters of nickel impurity atoms was determined. It was shown that in the process of thermal annealing within the temperature range 650…900 °С there is a significant change in the state, concentration, and size of clusters. Thermal annealing at the above temperatures, 650…900 °С leads to ordering the clusters, that is, self-assembly of cluster blocks, as well as clusters of a loop shape that includes several dozens of clusters. A diffusion technique to form and order clusters of nickel atoms in silicon has been suggested. en Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України Semiconductor Physics Quantum Electronics & Optoelectronics Hetero- and low-dimensional structures Clusters of nickel atoms and controlling their state in the silicon lattice Article published earlier |
| spellingShingle | Clusters of nickel atoms and controlling their state in the silicon lattice Bakhadyrkhanov, M.K. Ismailov, K.A. Ismaylov, B.K. Saparniyazova, Z.M. Hetero- and low-dimensional structures |
| title | Clusters of nickel atoms and controlling their state in the silicon lattice |
| title_full | Clusters of nickel atoms and controlling their state in the silicon lattice |
| title_fullStr | Clusters of nickel atoms and controlling their state in the silicon lattice |
| title_full_unstemmed | Clusters of nickel atoms and controlling their state in the silicon lattice |
| title_short | Clusters of nickel atoms and controlling their state in the silicon lattice |
| title_sort | clusters of nickel atoms and controlling their state in the silicon lattice |
| topic | Hetero- and low-dimensional structures |
| topic_facet | Hetero- and low-dimensional structures |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/215321 |
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