V.E. Lashkaryov Institute of Semiconductor Physics NAS of Ukraine
National Academy of Sciences of Ukraine

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#16 Department of photonic semiconductor structures

Karatchentseva  
 

Head of department,

Doctor of Technical Sciences

Karachevtseva Liudmyla


Phone: +38(044) 525-23-09

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Staff

Glushko       Glushko Eugene
Leading Researcher, Doctor of Physical and Mathematical Sciences, Professor.
Phone: +38(044) 525-23-09
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Karach

 

    Karas' Mykola
Senior Researcher, PhD
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Litvinenko

 

    Lytvynenko Oleg
Senior Researcher, PhD
Phone: +38(044) 525-23-09

Onishenko

 

    Onyshchenko Volodymyr
Researcher, PhD

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Konin

 

    Konin Konstantin
Researcher
Phone: +38(044) 525-23-09
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Stronska

 

   

Stronska Olena
Researcher
Phone: +38(044) 525-23-09
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Morozovska

 

    Morozovska Dina
Junior Researcher
Phone: +38(044) 525-23-09

 Иванов

 

 

 

Ivanov Vitalii
Junior Researcher
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Sapelnikova Olena
graduate student

 

 Pinchuk

 

 

Pinchuk Valentyna
Leading Engineer
Phone: +38(044) 525-23-09

 

#48 Laboratory of semiconductor infrared photoelectronics

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.

 

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а

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b

Two-dimensional macroporous silicon structures with periodic (a) and arbitrary (b) arrangement of cylindrical macropores. Macropores diameter: a – 6μm, b – 3 μm.

 

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 Uc, which is proportional to the square of the thickness of the silicon anode dc. 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 dc ≈ 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.

3 4

 

 

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).

 

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Fragment of macroporous silicon structure; Insert – scheme of formation of layers SiO2 and CdS-polyethylenimine.

 

AFM image of CdS nanocrystals; Insert – zone diagram of excitation of photoluminescence.

 

 

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/Hz1/2 in the range 1-10Hz, 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 Dλ = 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. For the first time in Ukraine, two-dimensional photonic macroporous silicon structures with a periodic arrangement of macropores with a diameter of Dp = 3 – 6 μm, depth to = 250 μm and a concentration of Np = 1.5×10см-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, = 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).

 

Design

1

Розробки-1

 

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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.

 

3

 Розробки-3

 

„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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Розробки-4

 

 

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Розробки-5

 

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Розробки-6

 

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Розробки-7

 

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:

- STCU project # 2444 "Development of active elements based on two-dimensional Si and InP photonic crystals for nanophotonic schemes" (2003-2006)

- scientific research work of young scientists on the grant of NAS of Ukraine (2005-2006).

- agreements on scientific, technical and scientific-pedagogical cooperation of the Kryvyi Rih Pedagogical University with the V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine (2005-2014)

- agreements on scientific, technical and scientific-pedagogical cooperation of the Kiev National University. Shevchenko with the V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine (2007-2010)

- agreements on scientific, technical and scientific-pedagogical cooperation of the М.P. Dragomanov Kiev Pedagogical University with the V. Lashkaryov Institute of Semiconductor Physics of NAS of Ukraine (2011-2014)

- the project "Development of elements of integrated nanophotonic circuits based on silicon photonic crystals" in the framework of the scientific work III-10-06 "New principles, methods and means for obtaining, researching and characterizing semiconductor materials and structures, creating an elemental base for advanced semiconductor electronics, including on the basis of new physical phenomena"(2008).

- the project "Development of active and passive elements of integrated nanophotonic circuits based on semiconductor photonic crystals" within the framework of the scientific work III-7-06 "Physical and technological research of semiconductor materials and low-dimensional structures for IR microphotoelectronics" (2008-2010).

- the project "Development of two-dimensional silicon photonic crystals with surface-active nanocoatings" within the framework of the scientific work III-41-07 "Physical and physical-technological aspects of the creation and characterization of semiconductor materials and functional structures of modern electronics" (2008-2011).

- the project "Development of uncooled photosensitive elements based on two-dimensional structures of macroporous silicon" within the framework of the scientific work №53 "Manufacturing and research of semiconductor nanostructures for the development of thermoelectric generators, uncooled photodetectors, thermal micro-emitters and photonic crystal waveguides" (2009)

- the project "Development of photodetector elements of optoelectronic devices based on semiconductor photonic crystals with nanocoatings" within the framework of the scientific work III-10-09 "Development of new principles, methods and methods for obtaining, researching and characterizing semiconductor materials and structures, creating an elemental base for advanced semiconductor electronics , including on the basis of new physical phenomena "(2009-2011).

- the project #6.22.5.15/20-GP "Development of nanotechnologies for the synthesis of ZnO and CdS nanoparticles for manufacturing light-emitting elements based on macroporous silicon structures with nanocoatings" (2010-2014)

- the project "Research, development and diagnostics of compact uncooled photovoltaic detectors based on two-dimensional macroporous silicon structures with SiO2 nanocoating" within the framework of the scientific work III-7-11 "Research, development and diagnostics of semiconductor devices for microwave and infrared nanophotoelectronics" (2011-2013)

- the project "Development of ionization substrates based on macroporous silicon structures for laser-desorption mass spectrometry" within the framework of scientific work III-10-12 "Development of advanced semiconductor materials and structures for opto-, micro- and sensor electronics" (2012-2013)

 

- the project "Creation and characterization of macroporous silicon structures with nanocoatings" within the framework of scientific work III-41-12 "Physical and physical-technological aspects of the creation of modern semiconductor materials and functional structures for nano- and optoelectronics" (2012-2013)

 

Publications

2017

 

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.