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


Department of Optics and Spectroscopy of Semiconductor and Dielectric Materials.    


Head of the Department
Prof. Dr. Yukhymchuk Volodymyr
Phone.: +380 (44) 525-62-40;
Internal phone: 3-29
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Prof. Dr. Mykhailo Valakh
Chief Researcher,

Corresponding member of NAS of Ukraine;

Phone.: +380 (44) 525-85-50;

Internal phone: 2-22
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Dr. Galyna Rudko
Leading Researcher

Phone: +380 (44) 525-83-03;

Internal phone: 4-91;
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Dr. Volodymyr Dzhagan
Leading Researcher

Phone: +380 (44) 525-83-03;

Internal phone: 4-29;

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Dr. Volodymyr Yefanov
Senior Researcher

Internal phone: 2-19;
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Yevgen Gule
Scientific Researcher

Phone: +380 (44) 525-83-03;

Internal phone: 7-15;

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Dr. Ivan Babichuk
Junior Researcher

Phone: +380 (44) 525-83-03;

Internal phone: 4-29;
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Larysa Chorna 

Leading Engineer
Phone: +380 (44) 525-83-03;

Internal phone: 4-29;



Dr. Oleksandr Hreshchuk

Scientific Researcher
Phone: +380 (44) 525-83-03;

Internal phone: 4-29;

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Dr. Yurii Romanyuk 
Junior Researcher

Internal phone: 5-95;

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Dr. Yevhenii Havryliuk
Scientific Researcher

Phone: +380 (44) 525-83-03;

Internal phone: 4-29;

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Oksana Isaieva
PhD Student

Phone: +380 (44) 525-83-03;

Internal phone: 4-91;

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Nazar Mazur
PhD Student

Phone: +380 (44) 525-83-03;

Internal phone: 4-29;

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Prof. Dr. Tarasov Georgy

Leading Researcher

tel.: +380 44 525-64-72

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Dr. Kulish Mykola

Leading Researcher

tel.: +380 44 525-62-82

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Dr. Zhuchenko Zoriana

Senior Researcher

tel.: +380 44 525-64-72

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IMG Golovynskyi 2    


Dr. Golovynskiy Sergii

Senior Researcher

tel.: +380 44 525-82-40

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Dr. Virko Sergii

Senior Researcher

tel.: +380 44 525-82-04

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Sonko Tetiana


tel.: +380 44 525-84-72




Alenichev Volodymyr


tel.: +380 44 525-84-72



Laboratory № 6.2  Laboratory of Radiospectroscopy

Head od Laboratiry Dr. Victor Bratus

Laboratory № 6.1  Laboratory of submicron optical spectroscopy

Head od Laboratiry Prof. Dr. Victor Strelchuk


Field of Researche

Directions of scientific research of Department:

  • Optics and spectroscopy of elementary and collective excitations in semiconductor and dielectric materials.
  • Physics and optics of semiconductor nanostructures.
  • Investigation of Raman light scattering, resonance Raman scattering, giant Raman scattering (SERS).
  • Radiospectroscopy of semiconductor and dielectric materials.
  • Optical and Magnetic Resonance Spectroscopy of polymorphic forms of carbon materials of different dimensions (graphite, graphene, nanotubes, fullerenes, and amorphous diamond-like films, coal).
  • Optical research of new multicomponent materials for photovoltaic conversion of solar energy (chalcopyrite, kesterity, stanity).
  • Optical and magnetic resonance diagnostic of materials.


Recent scientific achievements of the department

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Properties of the self-induced nano-islands fabricated by MPE technique
Giant interdiffusion in the nanostructures


Achievements 1

The results of Raman, local (nano) Auger spectroscopy, AFM and X-ray studies of Ge nanoislands on Si and CdSe on ZnSe, showed that the process of self-induced formation of nanoislands during molecular beam epitaxy growth can be described by Stranski-Krastanov mechanism only in the first approximation. In fact, the growth mechanism is complicated by abnormally intense surface interdiffusion of the components reinforced by the influence of inhomogeneous stresses. As a result the composition of nanoislands is mixed and non-uniform depending on the temperature of epitaxy and morphological characteristics of a nanoisland (the shape and size) (in collaboration with the departments #11 and #19).




x – average composition

ε – average stress


The measured lateral Auger-profile of the of Ge/Si – nano-islands at the levels 8, 17 і 27 nm from its apex supports the conclusion about the intense diffusion of Si from the substrate that causes the mixed Ge1-xSix composition of nano-island.


Due to inter-diffusion the dome-like nano-island that was grown by the epitaxy of Ge on the Si0,9Ge0,1 buffer layer (see the Figure) predominantly consists of silicon.



RS on the folded branches of acoustic phonons in superlattices with SiGe nanoislands


Achievements_6.png  Achievements 7




It is shown that the analysis of Raman scattering on the folded acoustic phonon branches in the superlattices of nano-islands must be carried out with the account of the real structure of the islands. It was demonstrated that Raman spectroscopy can provide is applicable for the analysis of the vertical alignment of nano-islands in the superlattices and for the estimation of their period.


Colloidal semiconductor nanocrystals

The study of the optical properties and vibrational excitations of colloidal nanocrystals (NC) CdSe, CdS, CdTe, ZnO, CuInS 2 are carried out in collaboration with Pisarzhevskoho Institute of Chemical Physics NAS Ukraine and the colleagues from the Technical University of Chemnitz (Germany), University of Oldenburg (Germany) and the Laboratory of Physics of Materials CNRS, Paris (France).

ДThe dependence of the photoluminescence spectra of the NC on the synthesis conditions (temperature, chemical reagents, post-synthesis chemical treatment), the structure and morphology of NC (average size, type of ligand, the presence and thickness of the shell of another semiconductor or passivator). It has been shown that:

  • The shell of a wide band gap semiconductor (e.g, ZnS shell and CdSe core) enhances the quantum yield of the photoluminescence (PL) due to the passivation of non-radiative recombination centers, and causes the "red" shift of the spectrum due to weakening of the confinement of charge carriers;
  • Size dependence of the phonons energy in A2B6 NCs is observed at the sizes less than 5 nm;
  • Additional spectral features related to the phonon density of states of surface atoms were observed in NC with the sizes less than 3-4 nm НК;
  • Size-selectiveness of resonance Raman scattering in the ensemble of NCs with large (>10%) dispersion of sizes was demonstrated; this finding explains the discrepancies in the previous literature data;
  • Resonance Raman spectroscopy provides selective excitation (by varying excitation wavelengths) of phonons in different semiconducting materials that compose nano-heterostructures;
  • The effect of components interdiffusion at the core/shell interface was observed in NCs. Observation of interdiffusion even at sufficiently low temperatures of NCs synthesis (100-200 C) is ascribed to inhomoheneous and strong mechanical stresses at the interface caused by the lattice mismatch between core and shell (11% in the case of CdSe / ZnS ).


Achievements 9

Typical resonance Raman spectra of NCs CdSe and CdSe/ZnS (left panel). Scheme of the core-shell NC CdSe/ZnS with the diffusion at the interface (right panel).


Optical and vibrational spectra of ultrasmall А2В6 nanoparticles

(in collaboration with Pisarzhevskoho Institute of Chemical Physics NAS Ukraine)


The phonon spectrum of the ultrasmall quasi-white light emitting NCs (less than 2 nm, also named magic crystals) is studied. The qualitative distinctions from the spectra of larger NCs - widening and low-frequency shift- were observed. These effects are related both to the phonons confinement and to the NC's lattice reconstruction caused by big number of surface atoms (about 50 % for the NCs of 1,8 nm size).



Optical studies of the spin-dependent processes in nano-structures based on the diluted magnetic semiconductors

Two cascades of hot exciton energy (momentum) relaxation within two spin-splitted hh-ecxitonic subbands were experimentally observed in nano-structures based on diluted magnetic semiconductors A2B6. This finding evidences that spin-flip process with the transition of excitons from the upper excitonic subbang to the lower one are less probable than LO-phonon assisted relaxation.

Strong influence of the spin splitting value on the spin relaxation of hh-excitons in the superlattice of ZnMnSe/CdSe was observed. Spin relaxation rate strongly increases at spin splitting values that exceed the LO-phonon energy value.

Two model spintronics devices that provide polarized spin state (spin polarizer) or swithch the spin polarization (spin swithch) were realized.


Achievements_11.png Achievements_12.png Achievements 13

Scheme of hot exciton energy (momentum) relaxation within two spin-splitted hh-ecxitonic subbands in nano-structures based on diluted magnetic semiconductors A2B6 in magnetic field.

Spin polarizer. Exciton polarization (spin) in the quantum well is independent on the energy of the exciting light quanta energy.

Spin switch. Change of the exciting quantum energy switches the excitonic polarization (spin) in the quantum well.



Optics and radiospectroscopy of carbon-containing materials


Graphene layers in the carbon nanocomposite. Carbon nanocomposite was fabricated by highly efficient technology of high temperature sublimation of polycrystalline silicon that was elaborated in our Institute (Department №7). The composites were studied by Raman spectroscopy and scanning electron microscopy methods. High content of graphene flakes in nanocomposite was obtained. The sizes of the flakes are up to tens of microns. These flakes are mostly high-quality defectless free-standing monolayers of graphene.


Achievements_14.png Achievements 15

Electronic micrograph of the surface of nanocomposite with the regions of disordered graphite (1) and graphene flakes (2)

Raman spectra of the nanocomposite:

1 – typical spectrum of the disperse region;

2 – spectrum from the periphery of a graphene flake;

3-4 – spectrum from the central part of a monolayer flake.


Optical analysis of the biomorphous SiC


Porous ceramics that was synthesized in the Institute (Department №7) by wood pyrolysis in the inert atmosphere and succeeding high-temperature soaking of the carbon skeleton obtained in liquid silicon. The ceramics was studied by optical and electron microscopy methods. It was shown that the composition of the ceramics depends on the ratio of masses of the initial components (C and Si). At Тc≈1500 оС the 3C- polytype is formed. The increase of the temperature up to 1800 оС causes the formation of 6H-SiC polytype.


Achievements_16.png Achievements_17.png Achievements_18.png


Natural carbon-based nanostructured materials


НComplex studied (SEM, RS, EPR, EDRS, theoretical calculations) of the natural nanostructured material – the coal from the Donetsk coal basin – revealed the fundamental correlation between the degree of metamorphism and energy capacity of coal on the one hand and coal composition, local structure and paramagnetic properties that have been formed during geological time intervals on the other hand.


Achievements_19.png Achievements_20.png
Dependencies of the ratio between the intensities of Raman lines (a) and concentration of paramagnetic defects (b) in coal depending on the concentration of volatile substance Vdaf.


To facilitate the analysis of exploding danger in coal mines the processes of gases diffusion in coal were analyzed. The correlation between the width of EPR line of electronic states of carbon and sorption/desorption processes was observed for hydrogen, oxygen, and methane. The comparison of the solutions of the corresponding diffusion equations with the experimental data showed that the diffusion is molecular and occurs via the open pores of coal. The diffusion coefficients for oxygen and hydrogen were obtained. Adsorption of oxygen was proved to be the main factor leading to the increase of EPR line width while substitution of oxygen by hydrogen or methane leads to line width decrease.

The enhanced concentration of iron in the coal samples from the mines with high rate of explosion danger was demonstrated; it can be one of key factors that enhance the risks of sudden explosions.


Defects in single crystalline silicon carbide


The knowledge and detailed understanding of formation mechanisms, structure and thermal stability of both native and radiation-induced defects is of utmost importance in view of prospective applications of silicon carbide in high-power, high-temperature and radiation-resistant electronics. The department conducts the corresponding studies by radio-spectroscopic and optical methods during recent years. Series of previously unknown defects that emerge under irradiation of SiC with electrons and neutrons were discovered. Their radiospectroscopic characteristics were measured and the models of the centers that include vacancies, interstitials and anti-site carbon atoms were proposed.


 Achievements_30.png EPR spectra of 3C-SiC crystal irradiated with neutrons before and after annealing. The spectra illustrate the emergence of new defects: Т1 - vacancy [VSi]-, Ку6 defect [VCCSi]-, Т6 defect [VCCi]0, Ку8 neutral carbon split-interstitial in the <100> direction.
The influence of the annealing-induced defect system transformation of the neutron-irradiated 3C-SiC crystals on their luminescent properties was observed. The anneals were carried out at high temperatures (600 OC .. 1000 OC)
 Achievements_31.png Typical PL spectra of the neutron-irradiated bulk 3C-SiC crystals before and after annealing. T=80 K, λexc.=514.5 nm. Narrow doublets at about 2.3 eV correspond to Raman lines.


Radiospectroscopy of radiation-induced defects in hydroxyapatites (HAP), EPR dosimetry and dating


Biological HAP is a base of solid tissues of animals and can be used in EPR dosimetry and EPR dating. Synthetic HAP is an important material for medical applications.

EPR studies have shown that the dominating paramagnetic centers that appear under γ- and UV-irradiation in carbonate-containing are axial and orthorhombic centers СО2-. The models of these centers are proposed and their paramagnetic parameters are found. It was found that the ratio of axial and orthorhombic centers is a characteristic parameter for each type of irradiation.

The number of γ-induced СО2- centers in biological HAP in the wide dose range demonstrates linear dependence on dose and is used in EPR dosimetry and EPR dating.

Achievements_23.png Achievements_24.png

Спектри ЕПР: EPR spectra: (а) lineshape variation at thermal annealing, (b) detailed comparison of EPR spectra of the un-annealed HAP (1) and HAP annealed at 360оС (2) ГАП.

Variation of the number of СО2- radicals in the irradiated HAP at annealing. The total amount of paramagnetic centers in the unannealed samples is assumed to be equal to 1.


Double electron-nuclear resonance tomography (ENDOR)


ENDOR tomography is a new method to obtain information about the microstructure of solids. Registration of ENDOR in inhomogeneous magnetic field provides data on the spatial distribution of complexes consisting of a paramagnetic center (PC) – a latiice defect – and bonded neighboring atoms. ENDOR method was proposed in the group of radiospectroscopy. The theory of this method was developed and the method applicability was first demonstrated for lithium fluoride single crystals using the equipment produced in the Institute.


Achievements_25.png Achievements_26.png

Model samples of LiF crystals: (а) continuous distribution of paramagnetic complexes, (b) distribution with the "hole" inside the sample. The paramagnetic centers used were F-centers (electron trapped by fluorine vacancy) with fluorine atoms that have magnetic moment.

ENDOR tomograms of the model samples of LiF crystals: а) with the continuous distribution of paramagnetic complexes, (b) for the samples with the "hole" in the distribution of centers.


Development of the methods of plasma-enhanced diagnostics ( SERS )


The reproducible substrates for stable plasmon-enhanced Raman diagnostics of molecular, biological and semiconductor systems are designed and fabricated (in collaboration with the Department 10). The fabrication of these substrates is based on the technology of holographic gratings production that have been previously developed in the Institute. The substrates were formed by gold deposition on the gratings that were formed by mutually perpendicular beams of argon ion laser. The effect of

The effect of significant Raman signal enhancement was recorded for both traditional dilute solutions of dye molecules and for the colloidal semiconductor nanoparticles of cadmium chalcogenides that were deposited from a solution.





Quaternary semiconductor materials for solar photocells of new generation


The scale of the world's photovoltaic solar energy conversion and as a result, a large total area of silicon-based ​​solar photovoltaic cells raises the problem of the transition to thin-film solar cells based on direct band gap semiconductors that unlike silicon can provide complete absorption of solar radiation at submicron thicknesses. In view of economical and environmental advantages the quaternary semiconductor analogues of the classical semiconductors АIIВVI are supposed to be the most promising compounds. The are named kesterites or stanites and their formula is А2IBIICIVD4VI, where А=Сu , В=Zn , С=Sn, Ge, Si, D=S, Se). In several years the effectiveness of the solar cells based Cu2ZnSn(S, Se)4 rapidly grew up and exceeded 10%. However, at the same time serious problems related to the physics and technology of multi-component crystalline materials appeared. The main problems are: existence of several phases with similar crystalline structure, possibility of significant composition inhomogeneity, huge (up to several percents) concentration of intrinsic defects in the cation sublattice. The studies by traditional X-ray methods are complicated due to the similarity of the characteristics of Cu and Zn cations.

In the framework of an international research project we demonstrated that Raman scattering is highly efficient for the diagnosis of the above problems as well as for the choice of optimal synthesis routes of these quaternary materials. The crusial role of the ratiobetween Cu and Zn atoms in kesterite or stanite structures for Cu2ZnSnS4 was proved.


Achievements_28.png Achievements_29.png

Microscopic image of the surface of a single crystal Cu2ZnSnS4:dark region - an area rich in Cu, light region - an area rich in Zn

Raman spectra of Cu2ZnSnS4: blue curve – an area rich in Cu (kesterite structure), red curve – an area rich in Zn (defect-rich kesterite with the symmetry of stanite).


5-volumes of the « Amusing optics» series


Achievements 32



dev01 dev02
(a) (b)

У відділі розроблені апаратно-програмні комплекси багатоканальної та одноканальної систем реєстрації слабких оптичних сигналів на основі ФЕП (a) та ПЗЗ-матриці (b).





Device for spectral filtering of radiation for laser and collimated light sources





Microwave modulator based on fast p-i-n diodes mounted into the microwave tract of the puls spectrometer-relaxometer (foreground block)




Microscopic addon for excitation of raman spectra, photoluminescence and object surface relief recording in ordinary and polarised light





Microraman facility based on DFS-52 (ДФС-52) specrtometer

Roraman facility based on DFS-24 (ДФС-24) specrtometer


MDR12 MDR23a

Facility for measuring luminescence in 200 nm - 4 μm spectral range based on MDR-12 (МДР-12) specrtometer

Facility for measuring transmission and reflection spectra in 200 nm - 2 μm spectral range based on MDR-23 (МДР-23) specrtometer



Facility for measuring luminescence in 200 nm - 4 μm spectral range based on MDR-23 (МДР-23) specrtometer




Spectrophotometer "Shimaszu RF-1501", spectral range 220 - 900 nm




Double beam spectrophotometer SF-20 (СФ-20), spectral range 200 - 2500 nm


  • «International cooperative programme for photovoltaic kesterite based technologies» (Marie Curie Actions - International Research Staff Exchange Scheme) 2010-2014 спільно з Fundacio Privada Institut de Recerca de L'energia de Catalunya в Barcelona, Universidad Autonoma de Madrid, Freie Universitet Berlin, Institute of Applied Physics of Academy of Sciences of Moldova, Belarussky Gosudarstvenniy Universitet Informatiki I Radioelektroniki.
  • «Carbon nanotubes technologies in pulsed fibre lasers for telecom and sensing applications»
  • (Marie Curie Actions - International Research Staff Exchange Scheme) 2011-2015.
  • Спільно з Aston University (Англія), Max Planck Gesellschaft zur Foerderung der Wissenschaften E.V. (Німеччина), TTY-Saatio (Фінляндія).
  • «Плазмонні суперструктури і поверхневе підсилення оптичного відгуку біомолекул та напівпровідникових квантових точок» 2011-2014. Спільно з Білкент університетом в Анкарі, Туреччина.
  • Спільний укр.-білор. проект № Ф54.1/005 «Взаємозв'язок оптичних, діелектричних структурних і компонентних характеристик четверних сполук халькогенідів міді та елементів II і IV груп як матеріалів нового покоління фотоперетворювачів сонячної енергії», в рамкам конкурсу ДФФД-БФФД 2013-2014 рр.
  • Спільний укр.-білор. проект № Ф54.1/013 «Напівпровідникові нанокристали (квантові точки) як перспективні раманівські мітки для біомедичних застосувань», в рамкам конкурсу ДФФД-БФФД 2013-2014 рр.
  • «Resonance- and plasmon-enhanced optical spectroscopy of semiconductor and coupled semiconductor-metal nanoparticles». 2010-2013. Спільно з університетом в Кемніці, Німеччина.
  • «Теоретичне та експериментальне дослідження ангармонізму та температурних ефектів в напівпровідникових наноструктурах»; 2011-2013. Спільно з Інститутом низьких температур та структурних досліджень, Вроцлав, Польша.
  • «Електронна структура кремнієвих квантових точок в германії». 2012-2013. Спільно з Інститутом фізики напівпровідників СВ РАН (Новосибірськ, Росія).
  • «Розроблення методу надчутливої поверхнево-плазмонно-підсиленої діагностики молекулярних, біологічних і колоїдних наносистем для потреб каталізу, медицини, фармакології та захисту навколишнього середовища» (тема №ДП) 2010-2013.
  • «Випромінювання та розсіяння фотонів напівпровідниковими квантовими точками в середовищах з різною топологією (плівки, фотонні кристали, плазмонні наноструктури)» Спільно з ІФ НАН Білорусі, Мінськ.
  • «Встановлення сукупності спектроскопічних характеристик вугілля, притаманних викидонебезпечним типам вугільних пластів» - «Метан». 2010-2012.
  • «Ефекти підсилення комбінаційного розсіювання й випромінювання світла в напівпровідникових наноструктурах». 2011-2012. Спільно з Інститутом фізики напівпровідників СВ РАН (Новосибірськ, Росія).
  • «Розроблення і створення комплексу неруйнівної діагностики хімічного складу та однорідності матеріалів і елементної бази сенсорних систем» (тема № 2.1.4/6) 2008-2012.
  • «Novel photonic materials based on nitrogen containing III-V ternary and quaternary alloys» (VISBY program projects in higher education and research 2010-2011). Спільно з університетом м. Лінчепінг (Швеція); факультет фізики, хімії та біології; відділ функціональних матеріалів електроніки).
  • «Фізичні механізми впливу деформаційних полів на самоорганізоване формування напівпровідникових наноструктур і варіювання цих полів для керування характеристиками наноструктур». (тема М/208) 2007-2008.
  • «Розробка принципів створення нанокристалічних матеріалів і вивчення спінових явищ в напівпровідникових наноструктурах для нового покоління пристроїв оптонаноелектроніки та спінтроніки» (тема № 33) 2007-2008.
  • «Нанозондові та оптичні дослідження впливу структурованих металічних шарів на випромінювання та розсіяння світла в напівпровідникових структурах» договір з МОН України Ф14.1/013. 2007-2008.
  • «Просторове впорядкування самоорганізованих напівпровідникових нанооб’єктів, сформованих на кремнієвих підкладках» (тема 35/23) 2008.
  • INTAS Project No. 00-761: «Novel carbon-based composite nanomaterials chemically produced from carbides». 2001-2004.
  • INTAS project No. 01-0444: Growth and optical investigation of self-assembled Ge/Si based nanostructures. 2002-2003
  • STCU No. 1830: «Розробка нової технології осадження та модифікації шарів на основі вуглецю для перспективних енергонакопичуючих приладів». 2001-2003.
  • INTAS Project No. 97-2141: «Investigation of ion implantation in silicon carbide for the fabrication of the advanced high power devices». 1998-2001.
  • INTAS Project No. 97-30834:  «Realisation of large-area High-voltage Power Devicesbased on Sublimation – Grown Silicon Carbide». 1999-2000.








































Prof. Tarasov Georgy

Leading Researcher

tel.: +380 44 525-64-72

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