Fields of research

Department of photonic semiconductor structures was established in 1998 in order to concentrate and coordinate scientific and technological resources, as well as intensifying the priority direction of research and technological work related to the development of highly efficient manufacturing techniques for active elements of nanophotonic circuits and optoelectronic devices based on photonic semiconductor crystals.

Scientific and technical activities of department are in the field of study of the formation of semiconductor photonic crystals and analysis of the impact of the transformation of the energy spectrum of electromagnetic radiation on the electronic and phonon systems of these structures. Also the researches are carried in the fields of establishment of mechanisms of interaction of electromagnetic waves with the nanocrystals on the surface of the structures and the development of highly efficient technologies of production of optoelectronic devices.

The main directions of scientific and technical activity: technology of semiconductor photonic structures; optics of two-dimensional photonic crystal, including three-component ones; optics of photonic membranes; photophysical phenomena in semiconductor photonic structures involving local surface states; development of technologies of production of active and passive optical and optoelectronic components.

Technology of semiconductor photonic structures. The modes of electrochemical formation of macropores in diffusively thin macroporous silicon structures have been worked out with a linear change of the applied potential, which is important for obtaining cylindrical macropores and controlling their diameter. The modes of electric field strength, which ensure a steady concentration of holes at the ends of the macropores during their formation are determined; the rate of change of the applied potential is calculated to provide the regime of stationary electric field strength.

The initial stage of macropores formation in silicon by electrochemical etching under steady-state illumination and constant current density was studied. It has been experimentally established that the process of macropores formation begins with a critical value of the voltage U_c, which is proportional to the square of the thickness of the silicon anode d_c. The observed dependence corresponds to the condition for the constancy of the hole concentration on the "silicon-electrolyte" surface and is fulfilled for the investigated system at a silicon anode thickness d_c ≈ 0.5L⁺ (L⁺ is the diffusion length of nonequilibrium holes in the field).

A comparative analysis of the surface of two-dimensional macroporous silicon structures by the methods of electron scanning microscopy, infrared absorption and modulation spectroscopy of electroreflection is carried out. It is established that the microstructure of the macroporous surface and the built-in electric field depend on the parameters of the electrochemical process: the output voltage and the current density; In this case, the value of the built-in electric field on cylindrical macropores is determined by the surface concentration of Si-O and Si-H bonds.

For use in heat-sensitive elements, diffusively thin silicon structures with a thickness of a macroporous silicon layer of 20-25 μm, which is 4-5 periods of the structure, are formed; For the first time, special types of macropores were found: conical and lateral, the formation of which increases the heat-insulating properties of the heat-sensitive element.

A method for chemical modification of macropore walls by forming SiO₂, Si-Al, Si-B, and SiC coatings on macroporous silicon by low-temperature gas-transport reactions is developed. The structures of the alloys of Si-Al, Si-B, and SiC composite materials on macroporous silicon with effective absorption of infrared radiation and low-resistance contacts are fabricated. It is established that at a current density exceeding the critical one, oxidized microporous layers form on the walls of macropores. For the first time, orange photoluminescence on macroporous silicon structures with nanocrystals with intensity of the order of 10 μW/cm² is detected, the structure and chemical composition of the radiating walls of macropores with microporous layers are determined. Ohmic contacts were made to the alloys of Si-Al, Si-B, and SiC composite materials on macroporous silicon with a low resistance value of 5-100 Ohm to form infrared radiation sensors. Macroscopic silicon structures with superdeep macropores (more than 300 microns) for controlling the substance in macropores were fabricated (L. Karachevtseva, O. Lytvynenko, K. Parshyn).

Optics of two-dimensional photonic crystals. The general features of the formation of the photonic band structure in two-dimensional photonic crystals such as macroporous silicon are theoretically established. The photonic band gap is measured on two-dimensional photonic macroporous silicon structures: the spectral position of the photonic band gap in the studied macroporous siliconstructures corresponds to the ratio of the lattice period and the wavelength of the incident light 2πa/λ = 5.

The mechanism of light absorption by macroporous silicon structures which is determined by the impurity effect of Franz-Keldysh was first established. Electro-optical energy and a change in the intensity of the built-in electric field are determined. Calculations of the electro-optical function of the first kind, the imaginary part of the permittivity and absorption of light by samples of macroporous silicon are carried out. It is shown that in the long-wave spectral range the absorption increases according to the law (hν)^3/2, and in the short-wave it decreases according to the law (hν)^1/2 in accordance with experimental data.

A program is developed for calculating the photonic band structure in one- and two-dimensional photonic crystals with third-order nonlinearity for a mixed system with a nonlinear nucleus. A new type of solution of the problem of propagation of electromagnetic radiation in the system "photonic crystal-nonlinear medium" is found using the Eli-function.

The band structures and state densities for two-dimensional photonic crystals under the condition that an additional layer with a different dielectric constant exists on the macroporous surface are calculated. It is shown that the presence of a surface layer significantly affects the photonic band structure and the width of the photonic band gap. A decrease in the width of the photonic band gap in the three-component oxidized macroporous siliconstructures is established.

A three-component structure in which a photonic band gap of 15.6% is realized in the range of optical communication wavelengths (1.55 μm) with a period of a = 1.5 μm, a fill-factor f = 0.8, a distance between macropores a - Dp = 200 nm	Structure of macroporous silicon with a layer of silicon oxide.

To study the localization of electromagnetic radiation by photonic silicon elements, programs for calculating photon elements by the finite difference time-domain method (FDTD method) were developed, which allows one to specify the required profile of the refractive index, the excitation regime, and the shape of the source of the electromagnetic field. The spectra of a two-dimensional photonic-crystal resonator based on macroporous silicon are calculated by the standing wave method. The spectra of two-dimensional photonic crystals, including finite and two-dimensional metamaterials, were calculated by the perturbation theory method in the zero approximation.

The realization of the Wannier-Stark effect at room temperature on the macroporous silicon structures with CdTe and ZnO nanocrystals on the macroporous surface is found and justified. Resonance oscillations of absorption with large amplitude are found, which are explained by the resonance scattering of electrons by impurity states on the surface of macropores during the motion of an electron in a strong electric field of the "silicon-nanocoverage" heterojunction. The Wannier-Stark states are stable due to the large scattering time relative to the period of electron’s oscillations in a strong electric field. The realization of the Wannier-Stark effect at room temperature on the macroporous silicon structures with layers of microporous silicon and silicon oxide 50-800 nm thick on the macroporous surface is also justified. A quadratic dependence of the electric field strength on the "silicon-nanocoating" boundary on the photon energy, which corresponds to the formation of waveguide quasi-directional modes on a silicon matrix and depends on the thickness of the oxide and the geometric dimensions of the silicon matrix, is established; The electric field strength in structures with a microporous layer does not change because of strong light scattering (L. Karachevtseva, O. Lytvynenko, K. Konin, O. Stronska, F. Sizov, Corresponding Member of the NAS of Ukraine (Department #15), S. Kuchmiy, Corresponding Member of the NAS of Ukraine (L.V. Pisarzhevskii Institute of the physical chemistry of the NAS of Ukraine).

The quantization of charge carriers in the near-surface region of oxidized macroporous silicon structures with ZnO and CdS nanoparticles has been revealed using modulation electroreflectance spectroscopy in the E₀' transition region and optical absorption in the near-IR spectrum range. It has been established that with an increase in the oxide thickness from 7 nm to 30 nm, the broadening parameter, the built-in electric field, the number of quantized levels increase. The application of pneumatic photonic crystals based on silicon as pressure and temperature sensors has been theoretically investigated. (L. Karachevtseva, O. Sapelnikova, L. Matveeva (Department #11)).

The mechanism of the effect of the electron-phonon interaction on the broadening parameter of the Wannier-Stark levels in the macroporous silicon structures with different concentration of Si-O-Si states in the surface layer of SiO₂ (TO and LO phonons) is established. The Wannier-Stark steps were determined from the oscillations of the IR absorption due to resonant scattering of electrons by surface states. The transformation of resonance scattering of electrons into the ordinary at ionized levels as a result of the interaction of surface phonon polaritons with electrons is revealed; While the scattering time decreases to the value of the period of electron oscillations in the near-surface electric field of the structures. (L. Karachevtseva, O. Sapelnikova, O. Lytvynenko, K. Parshyn, O. Stronska).

Effective light-emitting elements based on oxidized macroporous silicon structures with optimal depth of macropores and the thickness of SiO₂ nanocoating and a layer of CdS nanoparticles in polyethylenimine were fabricated. The deposition of light-emitting nanocrystals on the surface of oxidized macroporous silicon makes it possible simultaneously to increase the quantum yield of photoluminescence (up to 28%), to increase the strength of structures and to protect the surface from degradation. For structures with the optimum thickness of the SiO₂ layer, the quantum yield of photoluminescence increases during the first 2 weeks due to the evaporation of water molecules, and then stabilizes (L. Karachevtseva, O. Sapelnikova, O. Lytvynenko, K. Parshyn, O. Stronska).

On oxidized two-dimensional macroporous silicon structures in the IR region of the spectrum: (1) quasi-directional modes on absorption oscillations realized due to the Wannier-Stark effect are observed; (2) photonic forbidden bands are also measured. The high photoluminescence intensity of CdS nanoparticles on the macroporous surface is realized due to an increase in the electron flux from the silicon matrix toward the nanocrystal layer at the maximum electric field strength at the Si-SiO₂ interface, which substantially reduces the rate of nonradiative recombination. The phenomenon of multiplication of nonlinear optical diffraction on structured silicon substrates with liquid crystals is established. (L. Karachevtseva, O. Lytvynenko, K. Konin, K. Parshyn, O. Stronska).

 Photophysical phenomena in semiconductor photonic structures. The dependence of the photoconductivity and intensity of Raman scattering lines on the angle of incidence of electromagnetic radiation was first revealed. The experimental results that were obtained are explained by the formation of surface electromagnetic waves. It is established that the photoconductivity and its relaxation in the macroporous silicon structures is determined by the barrier on the surface of macropores. The ratio of the photoconductivity of macroporous silicon to the photoconductivity of a silicon monocrystal reaches a maximum at a distance between macropores equal to two thicknesses of the Schottky layer. The value of intrinsic photoconductivity is increased by more than 30 times relative to its value for single-crystal silicon (L. Karachevtseva, M. Karas’, V. Onyshchenko).

The electrophysical parameters and photoconductivity kinetics of the structures "metal-macroporous silicon" with ohmic and barrier contact are determined taking into account the series resistance, thermionic, generation-recombination and tunneling currents. It is found that the relaxation of the photoconductivity of macroporous silicon structures takes place according to the logarithmic law. The surface barrier of the structure "indium-macroporous silicon" is 0.031 eV, which correlates with the barrier on the free surface of macroporous silicon of the samples under study. The value of the series resistance and the saturation current components is determined: thermionic emission is 10^-7 A, generation-recombination is 10^-4 A, and tunneling is 10^-11 A. It is established that additional photoconductivity bands of composite structures of macroporous silicon with nanocoating SiO₂ and SiC are determined by impurity absorption on Si-H and Si-C bonds (L. Karachevtseva, M. Karas’, V. Onishchenko, A. Sachenko).

 The photo-emf of the anomalous sign was found in the structures of macroporous silicon for photon energies commensurate with the energy of the indirect band-band transition. It is established that the change in the sign of the photo-emf to the negative one is determined by photo-transitions through surface states close to the conduction band of silicon and by multistage tunneling recombination of equilibrium electrons in a silicon matrix with excited hole illumination on the macropores surface. This opens up the prospect of developing photovoltaic cells and waveguides based on macroporous silicon for functioning at a telecommunication wavelength of 1.55 microns. Macroporous silicon structures with a charged SiO₂ layer and a coating of CdS nanoparticles with an ultrahigh value of the voltage-watt sensitivity of 4500V/W (λ=0.95μm) at room temperature were fabricated (L. Karachevtseva, M. Karas’, V. Onyshchenko).

 Development of manufacturing technologies for optical and optoelectronic elements. Technologies for manufacturing compact uncooled heat and photodetectors based on macroporous silicon structures have been developed. To use photonic macroporous silicon structures in multichannel heat receivers of the infrared spectral range, an enriching contact of In to the layers of macroporous silicon made at different current density regimes has been made. The temperature coefficient of resistance of such a structure is 0.4-4%, the noise level (2-5)10^-9 V/Hz^1/2 in the range 1-10³ Hz, which coincides with the noise level of silicon substrates. A compact heat-receiving element based on macroporous silicon structures corresponds to the best samples of uncooled optical radiation detectors ("Uncooled heat receiving element for bolometers", Patent of Ukraine # 80345 IPC6 G01J 5/20, H01L 31/02 of 10.09.2007. / L.A. Karachevtseva, F.F. Sizov, Yu.V. Goltvyansky, K.P. Konin, O.J. Stronska, K.A. Parshyn, O.O. Lytvynenko). Technological operations for manufacturing a test position-photosensitive element based on In-macroporous silicon structures with a specific detectability up to D_λ = 10¹⁰ W^-1 cm Hz^-1/2 (λ≈1 μm) have been developed. The characteristics of the detectors exceed the parameters of the best samples for uncooled silicon microbolometers and pin-photodiodes due to the high absorption of light by the photonic structure in the current from the applied point of view of the spectral range of 0.5-14 μm and low noise level.

 Photonic silicon structures have been developed for the formation of active and passive elements of nanophotonic integrated circuits. The three-component structure based on a two-dimensional photonic silicon crystal makes it possible to realize the maximum width of the photonic band gap in the region of optical communication wavelengths (1.55 μm) while maintaining the strength of the photonic crystal ("Two-dimensional photonic crystal", Patent of Ukraine #83123 IPC (2006) G02V 5/00 of 10.06.2008 / L. Karachevtseva, O. Glushko).

A full-optical method for operating signals on the basis of the nonlinear photon-zone shift effect to create a full-optical adder was developed, as well as the structure of full-optical logical devices OR, AND, XOR in two possible R- and T- schemes. A new principle of image formation by designing rays by channels with absorbing walls for channel-imaging microscopy and telescoping was developed.

A theoretical analysis of microdevices based on two-dimensional photonic crystals for the control of optical signals is carried out. The model of a frequency selector and a polarization distributor based on integrated optical systems "waveguide-photonic crystal-waveguide" is calculated using the method of plane waves. It is established that the mode that propagates along the main waveguide with the frequency of the forbidden band of one of the photonic crystals is reflected in the sleeve of the lateral waveguide, demonstrating the selective properties of the system. The optical properties of porous channel photonic structures are investigated. It is shown that channeled (layered) materials belong to the type of metamaterials – meta-mirror structures with quasi-negative refraction.

 The application of pneumatic photonic crystals based on silicon as pressure and temperature sensors has been theoretically investigated. The contrast and sensitivity diagrams of silicon photonic crystals are calculated. It is shown that the sensitivity can reach 0.3-0.5 eV/bar for matrices of silicon, porous silicon and SiO₂ (E. Glushko, V. Evteev (Kryvyi Rih Pedagogical University)).

Achievement

The most significant scientific and technical results:

1. 1. For the first time in Ukraine, two-dimensional photonic macroporous silicon structures with a periodic arrangement of macropores with a diameter of D_p = 3 – 6 μm, depth to H = 250 μm and a concentration of N_p = 1.5×10⁶ см^-2 are fabricated. The process of photoanodic etching of silicon has been еnhanced taking into account the effect of bulk recombination on the current transport of holes to form parallelly arranged macropores on silicon with arbitrary resistance.
   2. In a single technological cycle, structures of macroporous silicon with nanocovering of microporous layers 100 – 700 nm thick were fabricated, for which photoluminescence was first detected (λ = 550 – 700 nm, I = 10 μW/cm²).
   3. The properties of three-component photonic macroporous silicon structures with SiO₂ nanocoating are investigated. Using computer simulation (the plane wave method), photonic band structures and state densities in photonic crystals with different symmetries and filling factors are obtained.
   4. The mechanism of light absorption by macroporous silicon structures, which is determined by the impurity effect of Franz-Keldysh was first established. The electro-optical energy, the imaginary part of the dielectric constant and the change in the intensity of the built-in electric field are determined.
   5. The mechanisms of the transport of photocarriers through the surface of macropores in the macroporous silicon structures are studied. It is established that the kinetics of the relaxation of photocarriers is determined by the barrier mechanism under conditions of charge exchange of the surface levels.
   6. The realization of the electro-optic Wannier-Stark effect at room temperature on the macroporous silicon structures with layers of microporous silicon and SiO₂ with a thickness of 50 – 800 nm on the surface of macropores has been detect and substantiated.
   7. The mechanism of the effect of the electron-phonon interaction on the broadening parameter of the Wannier-Stark levels in the macroporous silicon structures with different concentration of Si-O-Si states in the surface layer of SiO₂ (TO and LO phonons) is established.
   8. Light-emitting nanocoatings of polyethyleneimine with CdS nanocrystals on oxidized macroporous silicon structures have been developed. Thanks to the polymer basis, this technology allows simultaneously increasing the quantum yield of photoluminescence, increasing the strength of structures and protecting the surface from degradation.
   9. The patent of Ukraine "Two-dimensional photonic crystal", #83123 of 10.06.2008 (L. Karachevtseva, A. Glushko) received the nomination "The best invention of 2008 in the field of materials science", it solves the problem of realizing the maximum width of the photonic band gap due to the proposed ratio of the dimensions of the structure.
   10. Head of #16 Department L.A. Karachevtseva was awarded the International Association of Advanced Materials medal "IAAM Scientist Medal - 2016" for topical and outstanding research in the field of advanced technologies and materials (Stockholm, August 24, 2016).

2017

In 2017, department 16 carried out work on experimental and theoretical studies of macroporous silicon structures, structured silicon with liquid crystals, island photonic resonators, polymer nanocomposites. In 2017, department 16, in accordance with work plans, produced: (1) polymer films with multilayer carbon nanotubes 100-150 nm thick; (2) oxidized macroporous structures with SiO₂ thickness 4-200 nm and nanocoatings CdS nanoparticles and carbon nanotubes; (3) nonlinear optical cells based on periodic silicon structures filled with liquid crystals. Discovered: (1) an effective mechanism for increasing the strength of polymer-multilayer carbon nanotube composites by crystallizing the composite in its own electric field; (2) additional maxima with a half-width of 20-50 meV in the IR spectra of the photo-emf on the face “Macropore -nanocoatings SiO₂, SiC”; (3) the phenomenon of multiplication of a nonlinear optical pattern, sensitive to a change in the refractive index of structured silicon. The spectral distribution of electromagnetic energy inside the island photonic resonators “silicon-silicon oxide” and the contrast sensitivity in a gas medium have been determined 5.6·10^-4 per 1 bar change in external pressure, that is promising for the development of gas sensors and pressure sensors.

The results obtained are of scientific and practical importance, since they open up the possibility of increasing the strength of nano-coatings “polymer-multilayer carbon nanotubes”, the efficiency of multi-diffraction in nonlinear optical cells, the sensitivity of island photon resonators, the creation of infrared photodetectors with parameters close to the threshold parameters.

SEMICONDUCTOR MATERIALS SCIENCE AND SENSOR SYSTEMS

For the development of selective photovoltaic cells and optoelectronic sensors based on structures of macroporous silicon with nanocoatings worked modes of manufacturing nanocoatings based on polymer films with multilayer carbon nanotubes. It has been established that an effective mechanism for increasing the strength of polymer-multilayer carbon nanotube composites is crystallization of the composite due to the formation of C-C tetrahedrons using resonant vibrations γ_ω (CH) and γ_ω (CH₂) in its own electric field 6·10³ V/cm between nanotube and a polymer matrix. At the same time, the strength threshold for the polyamide-6 composite with 0.25% CNT increases 1.7 times, and the tensile strain - 2.3 times. Topic III-07-15 Section 7.2. (L.A. Karachevtseva, O.O. Lytvynenko, K.P. Konin, V.F. Onyshchenko).

TARGET SCIENTIFIC PROGRAM OF FUNDAMENTAL RESEARCH NAS UKRAINE (TOPIC III-41-17)

To develop functional structures and full-optical logic devices based on macroporous silicon with nanocoatings: (1) modes of cleaning the surface of two-dimensional structures of macroporous silicon and forming a nanocoating of silicon oxide with a thickness of 4-200 nm have been worked out; (2) the splitting of the energies of LO and TO phonons in IR absorption was investigated, which corresponds to an increase in stoichiometry at the silicon-silicon oxide interface with an increase in the oxide thickness to 15-20 nm, voltage relaxation in the silicon oxide layer at an oxide thickness of 20-50 nm; (3) analytical studies of the spectrum and distribution of electromagnetic energy inside island photonic resonators of finite dimensions – “silicon-silicon oxide”, “porous silicon” and “silicon oxide-silicon oxide”, located on a silicon substrate. Topic III-41-17 Subsection 1.6. Creation and characterization of structures macroporous silicon with nanocoatings (L.A. Karachevtseva, E.Ya. Glushko, O.O. Lytvynenko, K.P. Konin, V.F. Onyshchenko).

DEPARTMENTAL TOPICS OF FUNDAMENTAL RESEARCH (TOPIC III-07-16)

For structures of macroporous silicon, two maxima were found in the distribution of nonequilibrium charge carriers in the region of macropores and in a single-crystal substrate, associated with the absorption and diffusion of photocarriers in the presence of macropores. Polymer films with multilayer carbon nanotubes 100-150 nm thick. Measured IR absorption spectra of the obtained films of polymer composites were compared with films of pure polymers for subsequent deposition on macroporous silicon structures. In the IR spectra of the photo-emf. of the structures of macroporous silicon with nanocoatings SiO₂ and SiC in the wavelength range of 2-4 microns discovered absorption maxima of surface states at the boundary of “macropore -nanocoating” with a half-width of 20-50 meV. Topic III-07-16 Section 7.2. Development of selective photovoltaic cells based on macroporous silicon structures with nanocoatings and alloying impurities (L.A. Karachevtseva, E.Ya. Glushko, M.I. Karas', O.O. Lytvynenko, O.J. Stronska, K.P. Konin).

DEPARTMENTAL TOPICS OF APPLIED RESEARCH (TOPIC III-10-15)

For the development of photoelectric and optical sensors based on macroporous silicon, it were fabricated oxidized structures with nanocoatingsof CdS nanoparticles and carbon nanotubes with volt-watt sensitivity, respectively, about 5000 and 3000 V/W. Manufactured nonlinear optical cells based on periodic silicon structures filled with liquid crystals; the phenomenon of multiplication of a nonlinear optical pattern, sensitive to a change in the refractive index of silicon, was discovered. It has been found that a structured “black silicon” wafer has a high volume lifetime of minority charge carriers. For oxidized periodic matrix SiO₂/Si/SiO₂ / Air contrast sensitivity in a gas environment is 5.6·10^-4 to shift the edge of the spectrum area 10³ cm^-1 for each bar of change in external pressure, that is promising for the development of gas sensors and pressure sensors. Topic III-10-15 Subsection 7.2. Development of photoelectric and optical sensors based on macroporous silicon structures with nanocoatings (L.A. Karachevtseva, E.Ya. Glushko, M.I. Karas', O.O. Lytvynenko, D.V. Morozovs’ka, K.P. Konin, V.F. Onyshchenko, O.J. Stronska).

THE USE OF RESEARCH RESULTS IN THE NATIONAL ECONOMY.

In cooperation with the Institute of Physics of the National Academy of Sciences of Ukraine, nonlinear optical cells with liquid crystals based on periodic silicon structures were manufactured and investigated their parameters. In such cells, there is an increase in the diffraction efficiency by a factor of 4 and the nonlinear optical response by 30-40%, which is important for applications in multichannel adapters, switches and optical communication lines due to the multiplication effect .

COORDINATION OF SCIENTIFIC ACTIVITIES.

Scientific-technical and scientific-pedagogical cooperation: T. Shevchenko Kyiv National University; Kryvyi Rih Pedagogical University; NTUU “KPI.”

As part of the work under the Agreement on Scientific and Technical and Scientific and Pedagogical cooperation between Kryvyi Rih Pedagogical University and V.E. Lashkaryov Institute of Semiconductor Physics in 2017, IR transmission was calculated taking into account the spectrum of eigenmodes of a photonic resonator based on silicon and SiO₂ as well as porous silicon. Calculated density states of photonic modes and their contribution to transmission of external light at different angles of incidence in the photon energy range from 0 to 0.5 eV for the oxidized structure of macroporous silicon with a unit cell size of 1.0/4.0 microns and Si-air, with a cell of 0.5/0.5 microns for directions of the GM of the Brillouin zone.

2018

In 2018, department 16 carried out works on experimental and theoretical studies of macroporous silicon structures with nanocoatings , pneumatic photonic crystal, two-sided macroporous silicon structures. In the department according to work plans: (1) oxidized structures of macroporous silicon with a thickness SiO₂ 5-1200 nm; (2) macroporous silicon structures with nanocoatings of nanocrystals ZnO, CdS, SiC and microporous silicon; (3) two-sided macroporous silicon structures with coatings of CdS nanoparticles and carbon nanotubes in polyethyleneimine were manufactured. It is found: (1) new functional capabilities of oxidized structures of macroporous silicon with a thickness SiO₂ 800-1200 nm (an increase in the signal of electron paramagnetic resonance and GHz absorption as a result of the formation of deep P_b centers at the Si-SiO₂); (2) formation of spiral dislocations during the photoelectrochemical formation of macroporous silicon structures as a result of a temperature gradient along the sample axis “anode -cathode” in the electrochemical cell; (3) predicted opposite bending of zones with respect to the surface of each side of double-sided structures of macroporous silicon with nanocoatings. The ultra-low values of the gas filling pressure at the level 10^-5 Pa were determined by the pressure of the light beam during the passage of the pneumatic photonic crystal.

SEMICONDUCTOR MATERIALS SCIENCE AND SENSOR SYSTEMS

New functional possibilities of oxidized structures of macroporous silicon with a thickness SiO₂ 800-1200 nm. Using X-ray diffraction and splitting energies of longitudinal (LO) and transverse (TO) phonons in the IR absorption spectra of oxidized structures of macroporous silicon with a thickness SiO₂ 5-1200 nm discovered the presence of structural modifications of tridymite with a hexagonal phase SiO₂ and cristobalite-β with orthorhombic phase SiO₂ which are formed under high pressure conditions. In samples with a thickness SiO₂ 800-1200 nm measured the increase in the signal of electron paramagnetic resonance and GHz absorption as a result of the formation of deep P_b centers on the Si-SiO₂. Topic III-41-17 Division 1.6. Creation and characterization of structures of macroporous silicon from nanocoating (L.A. Karachevtseva, O.O. Lytvynenko, K.P. Konin, V.F. Onyshchenko).

TARGET SCIENTIFIC PROGRAM OF FUNDAMENTAL RESEARCH NAS UKRAINE (TOPIC III-41-17)

For the first time the formation of spiral dislocations was detected during photoelectrochemical the formation of macroporous silicon structures as a result of a temperature gradient along the axis of the sample “anode-cathode” in the electrochemical cell under the influence of the thermal effect of illumination on the anode surface and cooling with a solution of the cathode surface. It was found that after the generation of charge carriers by an electromagnetic wave of 0.95 μm with a small absorption depth, the initial distribution of excess minority charge carriers has two maxima (in the macroporous layer and in a single crystal substrate). To create optoelectronic devices with increased measurement accuracy, analytical and numerical studies of the reflection spectrum of a pneumatic photonic crystal were carried out depending on the pressure of the gas filling and the environment. To measure ultra-low pressure values at the level of 10^-5 Pa, the influence of the pressure of a light beam during the passage of a photonic crystal is taken into account. Topic III-41-17 Division 1.6. Creation and characterization of structures of macroporous silicon with nanocoatings (L.A. Karachevtseva, E.Ya. Glushko, M.I. Karas', О.O. Lytvynenko, V.F. Onyshchenko, K.P. Konin, O.J. Stronska, D.V. Morozovs’ka).

DEPARTMENTAL TOPICS OF FUNDAMENTAL RESEARCH (TOPIC III- 07 -1 6 )

For the development of selective photovoltaic cells and optoelectronic sensors, structures of macroporous silicon with nanocoatings were fabricated with separate photoconductivity bands in the region of 0.5 - 4 microns. Oxidized structures of macroporous silicon with nanocoatings of nanocrystals ZnO and CdS have additional maxima of photoconductivity in the 0.65 - 1.0 μm due to the formation of additional surface states and surface quantization of charge carriers. Structures of macroporous silicon with nanocoatings of microporous silicon and SiC are photosensitive in the 0.6 – 2 µm and are promising for registration of the “singlet-triplet” transition of excited oxygen at a wavelength of 1.27 µm and in telecommunication networks at a wavelength of 1.55 µm. The macroporous silicon structures with SiC nanocoating have common bands in the spectra of photo-emf and IR absorption of light: in the region of the middle of the forbidden zone, OH and CH₂ surface conditions. Topic III-07-16 Section 7.2. Development of selective photovoltaic cells based on macroporous silicon structures with nanocoatings and alloying impurities (L.A. Karachevtseva, E.Ya. Glushko, M.I. Karas', O.O. Lytvynenko, O.J. Stronska, K.P. Konin).

DEPARTMENTAL TOPICS OF APPLIED RESEARCH (TOPIC III-10-18)

Optimal modes of formation have been worked out and two-sided macroporous silicon structures have been created, coatings with CdS nanoparticles and carbon nanotubes in polyethyleneimine have been applied. IR absorption spectra of one- and two-sided macroporous silicon structures with CdS nanoparticles and multilayer carbon nanotubes in a polymer have been obtained; an additional effect of surface states on macropores into the absorption of the side of structures with CdS nanoparticles was found. To form transparent electrical contacts to two-sided macroporous silicon structures with nanocoatings, metal grids of aluminum were deposited. Preliminary measurements of the photosensitivity of each side confirmed the predicted opposite bending of the zones relative to the surface of each side at an external quantum efficiency of 1%. Topic III-10-18 Subsection 2.3.2. Creation of two-sided structures of macroporous silicon with nanocoatings for the development of solar cells (L.A. Karachevtseva, О.O. Lytvynenko, K.P. Konin, D.V. Morozovs’ka).

COORDINATION OF SCIENTIFIC ACTIVITIES.

Scientific-technical and scientific-pedagogical cooperation: T. Shevchenko Kyiv National University; NTUU “KPI”, State Higher Educational Institution “Kryvyi Rih State Pedagogical University” of the Ministry of Education and Science of Ukraine on the topic “Investigation of the optimal conditions for the passage of electromagnetic signals through a metastructure with a photonic gap in a full-optical logic device.”

Participation in the Project of scientific and technical cooperation between the National Academy of Sciences of Ukraine and the Ningbo University of Technology, China (2018- 2020).

Dr. L.A. Karachevtseva is a member of the Scientific Council of the O.O. Chuiko Institute of Surface Chemistry and a member of the editorial board of the scientific journal “Chemistry, Physics and Technology of Surface.”

2019

In 2019, Laboratory 8.1 carried out work on experimental and theoretical research: macroporous silicon structures with nanocoatings, with additional linear and circular dislocations; a dielectric photonic resonator in contact with the metal film; enhancement of photoconductivity in two-sided structures. In the laboratory, in accordance with the work plans: (1) a diffuse model of photoconductivity relaxation in macroporous silicon has been developed. It was found that the relaxation of photoconductivity occurs through the processes of exchange of current carriers between the conduction band in the bulk of the semiconductor and local “slow” surface levels; (2) the effect of the formation of narrow dips in the reflection spectra of terahertz radiation from a silicon and dielectric photon resonator in contact with a metal film to create effective filters, collimators and concentrators of infrared and terahertz radiation with a narrow bandwidth and a small beam divergence angle was established; (3) an increase in the photoconductivity by a factor of 1.5 was found with simultaneous illumination of both sides of the two-sided structure compared to the sum of the photoconductivity with separate illumination of each side; (4) found that the structures of macroporous silicon with additional linear and circular dislocations are promising for the development of polarizing optical devices and new metamaterials.

SEMICONDUCTOR MATERIALS SCIENCE AND SENSOR SYSTEMS

Ionization substrates based on macroporous silicon with a microporous layer have been developed for laser desorption mass spectrometry when measuring the ratio of the mass of ions to their charge under the conditions of ionization of high-molecular compounds without destruction of molecules for diagnostics in the field of nanophysics, nanochemistry, nanotechnology and nanobiology and technical conditions for them are registered. It is found that the structures of macroporous silicon with additional linear and circular dislocations are promising for the development of polarizing optical devices and new metamaterials.

TARGET SCIENTIFIC PROGRAM OF FUNDAMENTAL RESEARCH NAS UKRAINE (TOPIC III-41-17)

The relaxation of the distribution of excess charge carriers and photoconductivity in the structures of macroporous silicon versus the depth of macropores is studied. A diffuse model of photoconductivity relaxation in macroporous silicon has been developed. It has been found, that the effective lifetime of minority charge carriers in macroporous silicon is determined by the diffusion of charge carriers with an increase in the delivery time of nonequilibrium charge carriers from the substrate to the reombination surfaces of the macroporous silicon layer and is longer than the effective time of carrier recombination in the macroporous layer. It was found that the relaxation of photoconductivity (15 - 45 s) occurs through the processes of exchange of current carriers between the conduction band in the bulk of the semiconductor and local “;slow”; surface levels. Topic III-41-17 Subsection 1.6. Creation and characterization of structures of macroporous silicon with nanocoatings (L.A. Karachevtseva, О.O. Lytvynenko, M.I. Karas', V.F. Onyshchenko).

DEPARTMENTAL TOPICS OF FUNDAMENTAL RESEARCH (TOPIC III-07-16)

IR and gigahertz absorption and relaxation of photoconductivity in macroporous silicon structures with SiO₂ nanocoating have been investigated. The effect of the formation of narrow dips in the reflection spectra of terahertz radiation from a silicon and dielectric photonic resonator in contact with a metal film is established. The transformation of the windows of transmission and reflection of radiation from a metallized photonic resonator is investigated according to Fano resonance and resonance surface plasmons for creating efficient filters, collimators and concentrators of infrared and terahertz radiation with a narrow passband and a small beam divergence angle. Topic III-07-16 Section 7.2. Development of selective photovoltaic cells based on macroporous silicon structures with nanocoatings (L.A. Karachevtseva, E.Ya. Glushko, M.I. Karas', О.O. Lytvynenko, V.F. Onyshchenko).

DEPARTMENTAL TOPICS OF APPLIED RESEARCH (TOPIC III-10-18)

Two-sided macroporous silicon structures with a macropore diameter of 4±1 μm and a macropore depth of 140±10 μm were formed on a silicon substrate with abraded ( thickness 40-60 nm) and polished sides of the silicon substrate. An increase in photoconductivity by a factor of 1.5 was found with simultaneous illumination of both sides of a two-sided structure compared to the sum of photoconductivity with separate illumination of each side. The finite difference method was used to calculate the distribution of excess minority charge carriers along the profile of bilateral structures of macroporous silicon; it was found that structured surfaces scatter light, which increases its optical path and absorption inside the sample. Topic III-10-18 Subsection 2.3.2. Creation of double-sided structures of macroporous silicon with nanocoatings for the development of solar cells (L.A. Karachevtseva, О.O. Lytvynenko, M.I. Karas', V.F. Onyshchenko).

DEPARTMENTAL TOPICS OF APPLIED RESEARCH (TOPIC III-10-19P)

Mechanical damage to the structures of macroporous silicon with additional linear and circular dislocations has been investigated. Cylindrical dislocations are located around the defect perpendicular to the surface of the silicon substrate, and the spiral and cylindrical dislocations together form a group of circular dislocations. It was found that violation of the lattice parameter of silicon between macropores and spherical bending exist for all modes of sample preparation. Research is promising for the development of polarizing optical devices and new metamaterials. Topic III-10-19П Subsection “New functional capabilities of macroporous silicon structures with silicon oxide nanocoating” (L.A. Karachevtseva, О.O. Lytvynenko, K.P. Konin, O.J. Stronska, D.V. Morozovs’ka).

THE USE OF RESEARCH RESULTS IN THE NATIONAL ECONOMY.

In collaboration with the O.O. Chuiko Institute of Surface Chemistry NAS of Ukraine developed and registered technical specifications TU U 27.1-03291669-003:2019 for the use of an ionization substrate based on macroporous silicon for desorption mass spectrometry when measuring the ratio of the mass of ions to their charge under conditions of ionization of high-molecular compounds without destruction of molecules for diagnostics of biologically active molecules deposited on ionization substrates based on silicon. In addition to biological, medical, and biotechnological applications, the problems of diagnostics in the field of nanophysics, nanochemistry, nanotechnology, and nanobiology have come to the fore in recent years. At the same time, a significant direction in improving the methods of laser desorption mass spectrometry is the development of an efficient ionization substrate.

COORDINATION OF SCIENTIFIC ACTIVITIES.

Scientific-technical and scientific-pedagogical cooperation: T. Shevchenko Kyiv National University, State Higher Educational Institution “Kryvyi Rih State Pedagogical University” of the Ministry of Education and Science of Ukraine on the topic “Investigation of the optimal conditions for the passage of electromagnetic signals through a metastructure with a photonic gap in a full-optical logic device.”

Participation in the Project of scientific and technical cooperation between the National Academy of Sciences of Ukraine and the Ningbo University of Technology, China (2018- 2020).

Dr. L.A. Karachevtseva is a member of the Scientific Council of the O.O. Chuiko Institute of Surface Chemistry and a member of the editorial board of the scientific journal “Chemistry, Physics and Technology of Surface.” 

Design

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„Неохолоджуваний теплоприймальний елемент для болометрів”; Патент України на винахід, № 80345 МПК6 G01J 5/20, H01L 31/02 від 10.09.2007. / Л.А. Карачевцева, Ф.Ф. Сизов, Ю.В. Голтвянський, К.П. Конін, О.Й. Стронська, К.А. Паршин, О.О. Литвиненко.

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„Двовимірний фотонний кристал”; Патент України на винахід, № 83123 МПК (2006) G02В 5/00 від 10.06.2008. / Л.А. Карачевцева, О.Є. Глушко).

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Equipment

The department for carrying out scientific research and technological work has such equipment:

- Automated electrochemical installation for production of macroporous silicon structures

- Optical microscope NU with photodocumentation technique

- Hall effect measuring installation

- Automated installation for measuring the transmission spectra in the infrared range

Projects

The department carried out:

research projects of the DPA NASU:

- Topic III-41-12 "Physical and physical and technological aspects of the creation of modern semiconductor materials and functional structures for nano- and optoelectronics" (2012-2016).

- Topic III-07-11 "Research, development and diagnostics of semiconductor devices in microwave and IR nanophotoelectronics" (2011-2015).

- Topic III-10-15 "Development of methods for obtaining and metrological support of complex semiconductor and device structures” (2015-2017).

- Topic III-07-16 “Investigation of the physical properties of semiconductor materials and low-dimensional structures for multi-element matrix and linear receivers of IR and microwave radiation” (2016-2020).

- Topic III-41-17 “Search and creation of promising semiconductor materials and functional structures for nano- and optoelectronics” (2017-2021).

- Topic III-10-18 “Development of new methods for the formation of functional semiconductor materials and device structures” (2018-2020).

SFBR topic:

- “Investigation of the optimal conditions for the passage of electromagnetic signals through a metastructure with a photonic gap in a full-optical logic device” (state registration No. 0117U007110) (2017-2018).

international projects:

- Project of the Swedish Research Council (VR) under contract # 348-2014-4250 (2015-2017).

- Project of Scientific and Technical Cooperation between the National Academy of Sciences of Ukraine and the Ningbo University of Technology (China) - (2015-2017).

- Project of Scientific and Technical Cooperation between the National Academy of Sciences of Ukraine and the Ningbo University of Technology (China) - (2018-2020).

Agreement on joint activities between the State Higher Educational Institution “Krivoy Rog State Pedagogical University” and the Institute of Semiconductor Physics of the National Academy of Sciences of Ukraine (01.12.2016 - 01.12.2019)

Publications