Head of laboratory:  PhD. Adilov Muhammadjon Masharibovich e-mail: adilov@iplt.uz, muxammad.84@mail.ru

The "Applied Nanotechnology" laboratory specializes in materials science, technology and physics of new modifications of semiconductor materials, development and advancement of technologies for synthesizing ultra-pure nanomaterials, and manufacturing various devices based on them, studying the physicochemical properties of nanomaterials, and practical applications. The laboratory has many years of experience and achievements in this scientific field, including dozens of new technical solutions protected by patents in Uzbekistan and several other countries. The laboratory team consists of young specialists, experienced employees, and actively involves graduate and undergraduate students in their work.

Scientific directions of the laboratory

• Development of new plasma technologies
• Study of transport and relaxation processes in silicon and its oxide structures of various dimensionalities
• Porous micro and nano structures and materials based on them
• Plasma methods of atomic layer, chemical and physical deposition of films and coatings. (ALD, PEALD, CVD, PECVD, PVD)
• Development of various modifications of semiconductor materials for creating efficient converters of solar and thermal energy into electricity
• Formation, structure, size effects and their influence on the synthesis processes of nanocatalysts, nanostructures, and nanopowders
• Development of materials and designs of units for flow batteries
• Electrical discharge processes in metals, semiconductors, and dielectrics, nanomaterials based on electrical discharge processes
• Modification of electrophysical properties of materials under the influence of plasma

Dissertations successfully defended by laboratory staff in recent years:

2021 B.M.Abdurakhmanov. PhD dissertation on the topic "Modernization of the electric arc process of silicon reduction and the creation of electronic devices based on it." (supervisor, Doctor of Technical Sciences, Prof. M.Sh. Kurbonov).
2021 Sh.K.Kuchkanov. PhD dissertation on the topic “Thermal energy converters based on Si/Si and Si-Ge/Si film structures obtained by deposition from the gas phase and partially ionized flows” (supervisor, Doctor of Technical Sciences, prof. Kh.B. Ashurov).
2019 M.M.Adilov. PhD thesis on "Thermoelectric properties of granulated silicon" (supervisor, Doctor of Technical Sciences, Prof. Kh.B. Ashurov).
2019 A. Zaripov. PhD dissertation on the topic "Processes of electroerosive processing of dielectrics" (supervisor, Doctor of Technical Sciences, Prof. Kh.B. Ashurov).
2019 R.Kh.Ashurov. PhD dissertation on the topic "Ion-plasma formation of nanosized structures of silicon and silicon compounds" (supervisor, Doctor of Physical and Mathematical Sciences, Prof. B.E. Umirzakov).

MAIN SCIENTIFIC RESULTS

New technology for the synthesis of monosilane:

A fundamentally new alkoxysilane technology for the synthesis of monosilane based on the direct reaction of metallurgical silicon and ethyl alcohol has been developed. A technological scheme has been developed (Fig. 1) and an experimental bench has been created for the synthesis of ethoxysilanes by the direct reaction of ethyl alcohol and technical silicon in the presence of a copper-based catalyst.

Fig.1 Implementation scheme of the new synthesis process TEОS by direct reaction MG Si and ethyl alcohol.

A new design of equipment for the production of anhydrous (99%) ethanol has been developed and its installation has been carried out. A unit for the synthesis of monosilane and its purification has been created, where not only technological processes are being worked out and the target product is obtained, but safety precautions for these processes and environmental issues will also be worked out to simplify its introduction into production.

Fig.2 Comparison of the duration of the induction period of the reaction of ethanol with technical silicon in the known process (1) and in various variants of the new technological process (2-4).

 Technologies and designs of units of installations are protected by 4 patents of the Republic of Uzbekistan and 15 foreign patents (USA, Japan, China, South Korea, Russia, Taiwan and the EU).

Fig. 3 Pilot plants for the synthesis of TEOS (left) and monosilane with a reactor for the growth of polysilicon

New plasma technology for the production of metallic rhenium:

A new technology for obtaining metallic rhenium by reduction from ammonium perrhenate in a hydrogen plasma has been proposed, and a pilot plant has been created to implement this technological process with the release of experimental batches of the product. The degree of conversion of ammonium perrhenate was controlled by X-ray diffraction. The analysis of the elemental composition of the obtained product, performed by optical emission spectroscopy, indicates the reproducible production of metallic rhenium with a purity of not less than 99.9%. The optimal conditions for the conversion of AR-0 ammonium perrhenate to metallic rhenium with a yield of more than 95% were determined. The developed plasma technology allows reducing specific energy consumption by a factor of two and purified hydrogen consumption by more than four times.

Fig. 4 Appearance of the pilot installation (left) and view of the plasma burning process in the reaction chamber through the front viewing window.

Fig. 5. Raman spectrum of the target product obtained by plasma technology for the reduction of ammonium perrhenate	Fig. 6 XRD spectra of the target product

New types of thermal energy converters based on granular silicon:

Based on the results of the study of the first discovered thermovoltaic effect that manifests itself when heating samples of non-monocrystalline silicon modifications and the appearance of abnormally high values of specific thermoelectric power, it is proposed to use granulated silicon (GS) to create thermal energy converters. GS is a silicon powder of a given dispersion, the particles of which in the working fluid of the converter are not sintered or fused, but are brought into mechanical contact with each other while maintaining a nanoscale layer of silicon dioxide on their surface, which arises when silicon is ground in air. 

It has been established that carriers of charge are generated due to the absorption of sub-band photons involving deep energy levels associated with defects on the surface of the GS particles. These defects arise during the mechanical grinding of the raw material and, in conjunction with impurities that give rise to similar levels present or deliberately introduced into the initial raw material, result in the appearance of an electromotive force and current flow upon heating, in converters with a working body consisting of both homogeneous GS (Fig. 7) and samples with a working body consisting of mechanically contacting areas formed from silicon powders with electron and hole conductivity. The Zeebeck coefficient of GS at 500 K is more than 10 times higher, and the thermal conductivity is 7-9 times lower than that of monocrystalline silicon. This makes GS a promising material for use in thermoelectricity, whose electro-physical properties are determined, on the one hand, by processes characteristic of polycrystalline silicon, and on the other hand, by those for porous silicon. 

Designs of various types of thermal energy converters based on GS have been developed, including options in which not only heat of natural or technogenic origin, including concentrated solar radiation, but also pressure on the working fluid is used to generate electricity (Fig. 8 and 9). These developments, as well as new technologies for increasing the conductivity of GS's, are protected by 11 patents of the Republic of Uzbekistan.  

Fig. 9. A new type* solar module with heating of the working fluid 1 converter made of granular silicon, concentrated solar radiation (CSR) 2-ceramic case, 3-movable "hot" electrode with a shank 9, 4-fixed "cold" electrode, 5-dielectric case, 6 - receiving platform, heated by CSR (shown by arrows), 7 - copper plate, 8 - bellows with H2O vapor, 10 - heat pipe.

Development of ion-plasma technology for obtaining silicon with nanosized structures:

Analytical equipment has been developed and manufactured, which makes it possible to experimentally study the possibilities of obtaining nanosized silicon structures in the process of monosilane decomposition using both constant and high-frequency electric discharges.

Using a scanning probe microscope Solver Next, topographic and granulometric control of nanosilicon samples obtained using glow discharge plasma was carried out.

Fig.11. Topography of silicon surface with nanoscale structures.	Fig.12. AFM image of a nanosilicon surface	Fig. 13. Nanoprofilometry of the nc-Si surface

Fig. 14. Family of Raman spectra of silicon nanocrystals 16nm, 27nm and 50nm in size	Fig. 15. Photoluminescence spectrum of a sample obtained in the process of deposition of silicon nanostructures from a monosilane-containing mixture in the glow discharge mode

Nanosilicon samples were studied in the photoluminescence mode using an InVia Raman spectrometer. It is shown that the nanosilicon synthesized by us has photoluminescence in the region of 770-810 nm with a maximum at about 795 nm (Fig. 15), and this is a characteristic feature of the photoluminescence of nanosilicon structures.

Formation of layers based on Ge, Si, Sn under the influence of a partially ionized silicon flux:

A series of joint experiments on the growth of SiSn on the Si(100) surface at a temperature of 700 K and ion energies of 500 and 650 eV have been carried out at the MBE facility at the Institute of Semiconductor Physics in Novosibirsk. An analysis of the images of the surface of the films, obtained using AFM, showed that under the influence of ions, the accumulation of tin atoms on the surface of the films sharply decreases from 7.4x10-7 cm-2 to 1.8x10-7 cm-2.

By optimizing the growth of SiGeSn and SiSn heterostructures on a Si(100) substrate with the participation of a partially ionized flow, with and without biasing the accelerating voltage, a model for the growth of multilayer heterostructures is constructed.

Raman peaks corresponding to vibrations of Sn-Si and Sn-Sn bonds in heterostructures based on Si(1 – x)Snx solid solutions have been experimentally detected for the first time. The photoluminescence bands found at low temperatures in heterostructures can be associated with optical transitions in quantum wells in the Si/Si(1 – x)Snx heterostructure of the second kind, as well as with excitons localized in tin nanoinclusions.
The possibility of ion-stimulated incorporation of tin atoms into the silicon crystal lattice during deposition from a partially ionized flow has been shown for the first time.

Fig. 16 - Raman spectra of Si/Si0.75Sn0.25 heterostructures (curve-1) and Si/Si0.9Sn0.1 (curve-2)	Fig. 17. Photoluminescence spectra of Si/Si0.75Sn0.25 (curve 1) and Si/Si0.9Sn0.1 (curve 2) heterostructures at low temperature. The inset shows a diagram of optical transitions corresponding to the peak indicated by the up arrow.

Obtaining porous silicon and nanostructures based on it:

Methods for obtaining silicon samples with varying degrees of porosity have been worked out and modern methods for analyzing such nanosized objects by Raman scattering and spectral ellipsometry have been mastered. Raman scattering and photoluminescence measurements showed the presence of silicon nanocrystals in the structure of porous silicon. On samples of porous silicon with a pore diameter of ~ 2 µm and a depth of ~11 µm, nanoscale layers of titanium and zinc oxides were created by atomic layer deposition.

Preparation of nickel oxide nanoparticles:

It was found that their average size is ~12 nm. IR spectroscopy indicates a typical range of vibrations for NiO in the range of 483 ÷ 719 cm-1, and Raman spectroscopy revealed a peak at a frequency of 509 cm-1 (Fig. 21), which unambiguously confirms the possibility of using NiO nanoparticles as a catalyst in the synthesis of carbon nanotubes.

Fig20. IR-Fourier patterns of nickel oxide nanoparticles after annealing at 700 K	Fig.21. Raman spectra of NiO nanoparticles annealed at 700K

Fig. 22. TEM micrographs of carbon nanotubes

Using the nanoparticles obtained from nickel oxide, carbon nanotubes (CNTs) were fabricated by the CVD method, and ethanol vapor purified in a special installation was used as a hydrocarbon source. Synthesis of CNTs was carried out at a temperature of 800 K for 30 min. , and the characteristics were studied using Raman spectroscopy and transmission electron microscopy (TEM), the results of which are shown in Figs. 22. With the help of the described technological methods developed in the laboratory, the production of single-walled CNTs with a diameter of ~2 nanometers has been launched. 

Development of a vanadium flow battery:

Vanadium flow redox batteries, a typical diagram of which is shown in fig. 23, are an integral part of modern energy storage systems obtained from alternative sources.

Fig. 23 - Scheme of a cell of a redox battery in the option of using vanadium salts with different valences in a solution of sulfuric acid as catholyte 4 and anolyte 5. 1 - working part, that is, an electrochemical reactor with negative 2 and positive 3 electrodes, anolyte 4 and catholyte 5, supplied from separate tanks 6 and 7 using pumps 8 and 9 in the cavities of the electrochemical reactor, separated by a separating membrane 10, passing ions of the same sign ( H+), 11-load. Solid arrows show the course of electrons and ions during discharging, and dotted arrows show the course of accumulator charging from PV.

The laboratory is working on a set of tasks related to the creation of domestic samples of redox batteries using local raw materials.

So, based on the recycling of vandium-containing waste, available in the Republic of Uzbekistan for the production of sulfuric acid, an environmentally friendly technology for manufacturing the main reagent - (V2O5) for a vanadium flow battery is proposed.

As a result of experimental research and experimental prototyping using a 3D printer, a new design of a vanadium flow battery has been proposed.

A new method for the synthesis of hybrid proton-exchange membranes based on polyvinyl alcohol, which are one of the main components of the electrode block of vanadium flow batteries, has also been mastered (Fig. 24). Membranes by this method are produced by organic crosslinking with the inclusion of silicon dioxide nanoparticles in the polymer matrix, obtained by the sol-gel method also in our laboratory. The characteristics of the membranes were evaluated by infrared spectroscopy, Raman scattering and X-ray phase analysis. The swelling, proton conductivity and permeability for vanadium ions were also determined in comparison with those of commercial Nafion 117 membranes. It was shown that the hybrid membrane developed by us has a proton selectivity of 0.78 105 S. min cm-3, which is significantly higher than that of Nafion 117 membranes, in which this indicator is 0.41 105 S min. cm-3. Tests of flow batteries with hybrid membranes showed high Coulomb and energy efficiency - 63.3% versus 70% at a current density of 100 mA cm2 and a lower self-discharge rate compared to Nafion 117 membranes. It has also been established that hybrid membranes remain stable after 100 cycles.

Fig. 24 - Appearance of the obtained membranes and comparison of one of their most important operational characteristics with that of commercial Nafion 117 membranes.

Developments for the benefit of agriculture in the Central Asian region:

For use mainly in agricultural production, in the Central Asian region, characterized by dustiness of the surface layers of the atmosphere and high summer temperatures, including in places remote from mains water and electricity, as well as in the processing of agricultural products, the laboratory staff carried out developments on :

a) the creation of a portable solar battery with a rear contact grid and solar cells based on relatively cheap secondary cast polycrystalline silicon, which allows, by increasing the transmission of the non-photoactive IR component of solar radiation, to reduce the equilibrium temperature of solar cells and, thereby, prevent a sharp drop Efficiency of solar batteries operated in the hot climate of the region;

b) modernization of devices for photoelectric stimulation of the process of forcing seedlings of elite plants. The development is based on the experimental fact of an anomalous drop in the current of solar cells made from the edge regions of ingots of secondary cast polycrystalline silicon when they are heated to temperatures of ~330 K and above, which is usually observed in practice.

c) the creation of a solar photovoltaic plant, operated mainly in the system of water lifting from wells in pastures in the steppe and semi-desert regions of the region, the design of which provides for passing a small part of the flow raised from the water well through a narrow spinneret located in the upper part of the solar batteries with the provision due to adhesion that it flows around the entire outer surface of the battery with the collection of passed water in a tray installed at the bottom of the solar battery and its return to the general flow. This technique ensures, firstly, the exclusion of power losses of the solar station due to dusting of the front surface of the cover glass of the solar battery, and, secondly, it prevents the efficiency loss of solar cells from overheating in the summer, and also protects the cover glass from ice and snow.

d) the creation of solar household salt water desalters from wells and other sources in which, in order to guarantee water disinfection, it is planned to deliberately introduce into the source water placed in the hot box type desalter a bactericidal substance such as a solution of potassium permanganate, an infusion of common harmala, alum solutions, etc., selected as well as those listed with the provision of coloring the source water in colors that increase the absorption of solar radiation, and hence the productivity of the desalinator. All listed developments are protected by Patents.

Another example of work in the interests of agriculture is the result of the development of a plant for freeze-drying vegetables and fruits. carried out in the laboratory. Figure 25 shows the appearance of this installation, the design of which embodies the extensive experience of the laboratory staff with vacuum equipment and their knowledge of the modern element base. An instance of the installation is introduced into the national economy.

Fig. 25 Freeze drying unit developed by our laboratory

Main experimental facilities and equipment

The laboratory is equipped with an experimental base that allows conducting research at the level of modern standards. The material and technical base of the laboratory includes modern facilities that implement the processes of gas-phase, ion-stimulated vacuum and plasma-chemical production of semiconductor materials and micro and nanoscale films, a monosilane production complex, complexes for electrophysical measurements of semiconductor parameters and analysis of their composition, a chemical laboratory with the appropriate equipment, as well as a class 1000 cleanroom with an area of 84 square meters. In addition to year-round air filtration from dust particles, it maintains a stable temperature, pressure and humidity. Inside the clean room there are growth units for atomic layer and chemical deposition, a spectral ellipsometer, work tables for performing work requiring extra clean conditions.

Fig. 26 General view of a clean room

Fig. 27 Growth cluster of atomic layer, chemical and plasma-chemical deposition (PEALD, PECVD) with a vacuum loading lock

Fig. 28 Liquid and gaseous nitrogen production station

Fig. 29. Installation of physical vapor deposition in high vacuum

Fig. 30. Planetary ball mill "PM 400" manufactured by RETSCH

Lab Collaboration:

Scientific research and applied work is carried out by the laboratory staff in contact with a number of domestic and foreign organizations. :

• OCI Corporation, South Korea
• Belarusian State University, Belarus
• Institute of Semiconductor Physics SB RAS, Russia
• National Solar Institute Gurgaon NISE, India
• Bilkent University - National Nanotechnology Research Center (UNAM), Türkiye
• Institute of Applied Physics at the Technical University Bergkakademie Freiberg, Germany
• National University of Uzbekistan
• Technical University of Uzbekistan
• Tashkent Presidential School
• Materials and Energy Research Center of Iran (MERC)
• Department of Mechanical and Industrial Engineering Indian Institute of Technology Roorkee
• Symbiosis Institute of Technology, Symbiosis International (Deemed University), Pune.
• Mersin University, Mersin, Türkiye
• Institute of Polymeric Materials, Ministry of Science and Education, Azerbaijan
• Andronikashvili Institute of Physics, Department of Plasma Physics, Tbilisi, Georgia
• Faculty of Mechanical Engineering Technology, University Malaysia Perlis
• Khujand State University. B. Gofurova, Khujand, Tajikistan
• Andijan State University named after Z.M. Bobur, Andijan.
• Almalyk Mining and Metallurgical Combine (AGMK)
• "Navoi Mining and Metallurgical Combinate" (JSC "NMMC>") ,
• Leninabad Mining and Metallurgical Plant, town of Choirukh-Dairon, Tajikistan

Projects:
2019-2020 MRB-AN-2019-26 Uzbek-Belarusian joint project "Develop and research new metal-oxide composite materials for electronic, electrical industry and other applications"
2021-2022 Draft program of innovative research Ministry of Innovative Development of the Republic of Uzbekistan. FZ-2019081456 "Obtaining metallic rhenium from ammonium perrhenate using plasma"
2012-2016 Draft program of fundamental research Ministry of Innovative Development of the Republic of Uzbekistan. OT-F3-11 "Investigation of transfer and relaxation processes in the structures of silicon and its oxide of various dimensions from the point of view of materials for alternative energy and nanoelectronics"