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Laboratory of photoelectric phenomena in semiconductors
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Lyudmyla V. Borkovska Cand. Sci. in Phys.&Math. Phone: +38 044 525 63 40 E-mail:
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Staff
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Nadiia O. Korsunska Leading scientist, Doct.Sci. in Phys.&Math., Prof. phone (044) 525 72 34, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.
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Iryna V. Markevich Leading scientist, Doct.Sci. in Phys.&Math. phone (044) 525 72 34 |
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Volodymyr O. Bondarenko Senior researcher, Cand. Sci. in Phys.&Math. phone (044) 525 57 75, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. |
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Natalia I. Kashirina Senior researcher, Cand. Sci. in Phys.&Math. phone (044) 525 63 40, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. |
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Volodymyr I. Kushnirenko Researcher |
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Tetyana R. Stara Senior researcher, Cand. Sci. in Phys.&Math. phone (044) 525 72 34, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. |
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Nataliya O. Tataryn engineer phone (044) 525 63 40, e-mail:
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Larysa Yu. Khomenkova Senior researcher, Cand. Sci. in Phys.&Math. phone (044) 525 57 75, e-mail: This email address is being protected from spambots. You need JavaScript enabled to view it. |
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Vitaliy A. Chernobay Leading Engineer |
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Lyudmyla V. Shcherbyna Senior researcher, Cand. Sci. in Phys.&Math. |
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Oksana B. Yastrubchak Doctorant, Cand. Sci. in Phys.&Math. phone (044) 525 63 40, e-mail:
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Field of Research
The main scientific and technichal activities of the department are focused on the study of nonequilibrium electronic and ionic processes in semiconductor materials and devices occured under irradiation of light and ionizing radiation as well as under carrier injection from the contacts and p-n-junctions.
In recent years, research and technical work flow is going in several directions:
- Experimental and theoretical studies of nonequilibrium processes in light-emitting semiconductor nanostructures based on A2B6 compounds (CdSe, CdTe, CdS, ZnSe) and their solid solutions (ZnCdSe, ZnCdTe, CdSeTe) as well as on A3B5 compounds (InAs, InGaAs, InGaAsN, InGaAsSb), obtained by the methods of colloid chemistry and molecular-beam epitaxy) that are promising for the development of lasers, LEDs and fluorescent markers of biological objects. Investigation of the effect of technological parameters and post fabrication treatments (annealing, irradiation and biomolecule conjugation) on the structural and luminescence characteristics of these nanostructures with the aim to improve their light-emitting properties and to establish the mechanisms of their degradation.
- Invesitgation of the structural and luminescent properties of oxide layers (SiO2 and Al2O3) with embedded silicon nanocrystals versus fabrication conditions and subsequent thermal treatments in order to clarify the mechanisms of nanoscrystals' formation and to establish the nature of radiative transitions as well as to develop the methods for optical characteristics' control.
- Investigation of diffusion and drift of intrinsic point defects and impurities (Cu, Ag, Mg) in bulk and polycrystalline semiconductors A2B6 (CdS, ZnS, ZnO) in order to establish the nature of the centers responsible for impurity-related photoluminescent bands and types of radiative transitions, and to examine the possibility of shalow acceptors' formation in n-type materials.
- Fabrication of undoped and doped with group I elements (Li, Na, K, Cu, Ag) ZnO and ZnMgO ceramics, as well as the investigation of their structural and luminescent properties to obtain white-light luminescent emission.
- Development of theoretical methods and the calculation of energetic structure of two-electron systems with electron-phonon interaction in semiconductors.
Achivements
Most significant scientific and technical results obtained in the department:
Based on theoretical consideration of general scheme of recombination transitions in photoconductors containing different types of recombination centers and the level of the capture of major carriers, the complex of methods for the joint study of photoconductivity and recombination luminescence based on the study of their stationary and mainly kinetic characteristics (V.E. Lashkarev, I.B. Ermolovich , A.V.Lubchenko , M.K. Sheinkman, 1960-1968)
For the first time, all parameters (such as concentration, energetic positions in bandgap , capture cross section of electrons and hole , energy of photons required for electron transition from the valence band to the centers and from the centers of the conduction band , the degree of electron-phonon interaction) were identified for photosensitivity centers. The mechanisms of radiative recombination for most important A2B6 (CdS, CdSe, CdSSe, ZnSe, ZnTe, CdTe, Zn), A3B5 (GaAs), A3B6 (GaSe, InSe) and other semiconductors were established (V. Lashkarev, I. Gorodetsky, I. Ermolovich, N. Korsunska, A. Lubchenko, M. Sheinkman). These results have been the basis for development of new types of photo-detectors and converters for a wide range of the electromagnetic spectrum. This work was awarded the USSR State Prize in the field of Science and Technology (M.K. Sheinkman, 1984).
M.K. Sheinkman for the first time considered a new type of centers’ interaction (similar to Auger interaction). It was supposed that the energy, released upon carrier capture by the center, is transferred to the carrier located at nearby center. Novel mechanism of nonradiative recombination was proposed theoretically and implemented for explanation of the phenomena of impurities’ interaction in semiconductors (V.I. Dyakin, E.A. Sal'kov, V.A. Khvostov, M.K. Sheinkman, N.O. Korsunska, I.V. Markevich , T.V. Torchynska ).
On the basis oftheoretical consideration(M.K. Sheinkman, 1972) for the first time physical model of heterogeneous systems was proposed, that allowed a large group of the phenomena of long-time relaxationcurrent (the so-called residualconductivity) in different semiconductor materials to be explained (I.V. Markevich, V. A. Khvostov, M.K. Sheinkman, 1973).
Based on detailedtheoretical analysis(S.S.Ostapenko), the complex of polarization methods for the investigation of luminescence spectra and photocurrent excitation was developedthatallowed to establishthemodel of main luminescent centersin A2B6 materials (S.S.Ostapenko, M.A.Tanatar, M.K.Sheinkman).
New fundamental type of non-equilibrium processes, i.e. the processes of defects' transformation under illumination and X-rays irradiation as well as under carriers' injection was investigated by N.O. Korsunska, I.V. Markevich, T.V. Torchynska, M.K. Sheinkman. A detailed investigation of the nature of these processes (so-called "photochemical reaction") in A2B6 semiconductors has revealed several types of reactions. The nature and the mechanisms of these processes were established. Their important role in the degradation of optoelectronic devices, for instance, photodetectors based of A2B6 semiconductors, was demonstrated.
Experimental andtheoretical studies ofelectroluminescencedegradationof LEDs based on A3B5 semiconductors(GaAs:Si, GaP:N) allowed to propose the modelof the degradation and to identify thetypes andmechanisms ofrecombination-stimulated reactionsdefects cause LED degradation (T.V.Torchynska).
The processes of reconstruction and generation of the defects under ultrasound treatment and laser irradiation were observed by S.S.Ostapenko, N.O.Korsunska, M.K.Sheynkman. In particular, it was shown that ultrasoundsignificantlyaccelerates thehydrogenpassivationof the surfacecenters inpolycrystalline silicon(S.S.Ostapenko).
The mechanism of degradation of the active elements based on CdS crystals of the lasers with electron pumping was established. The threshold of surfacedamage of laserscreens depends on the technologyof CdS crystal growth and it is determined by the typeof macrodefects, i.e. grain boundaries, when crystals weregrownwith an excess ofsulfur vapor, andcadmiumphaseinclusions for the crystalsgrownby excess of cadmium vapor (N.O.Korsunska, A.F.Synhayivskyy, G.S.Pekar).
Theoretical and experimental investigation of the electro-diffusion of the defects showed that the use of external electrical field allows to reduce of doping temperature, to identify local centers formed by impurity atoms, to accelerate and simplify the definition of the parameters and the mechnisms of the diffusion of defects investigated as well as to implement this method for the purification of crystals from impurities.
Using the method of electro-diffusion, the effect of local centers, associated with Cu and Ag in CdS, ZnO and ZnS crystals, on their photovoltaic and luminescent properties was investigated. It was demonstrated the role of impurity atoms in the photoinduced reactions of the defects in CdS:Cu and CdS:Ag crystals. The diffusion anisotropy of Ag and Cu ions in CdS crystals in different crystallographic directions was found. The effect of "anomalous" drift in CdSe crystals was investigated. It was shown that the "residual" donors in ZnO are Zni mobile interstitials and the effect of there moving under insternal and esxternal electrical fields on exciton and "impuritiy" luminescence was discovered (I.V. Markevich, N.O. Korsunska, L.V. Borkovska, L.Yu. Khomenkova, V.I. Kushnirenko).
The mechanism of radiative transitions caused by AgZncenters in ZnO ceramics was established. It was demonstrated that AgZn creates a shallow level in ZnO bandgap, whereas LiZn, NaZn, KZn are deep acceptors resulted in the luminescence in 580-620-nm spectral range.
Based on the theoretical analysis of the processes of defect drift in the electric field is was shown that the process of electro-diffusion cleaning of the semiconductors can be significantly accelerated due to deformation effects. The latter may occur even for uncharged defects (N.I. Kashirina, M.K. Sheinkman).
In 1983 M.K. Sheinkman proposed an alternative explanation of recombination-stimulated diffusion of the defects in semiconductors based on the diffusion of defects in the excited state.
A new mechanism for variation of diffusion barrier of vacancy centers in ionic crystals associated with the capture of two electrons in anti-binding state. Numerical simulations of this variation in the case of the capture of one or two electrons in the binding and anti-binding states were performed for vacancy centers (F- and F'- centers) in alkali-halide crystals. (N.I. Kashirina, M.K. Sheinkman).
Low-dimensional organic conductors with promising new mechanisms of superconductivity with high critical temperatures have been investigated in 1978-2001. Systematic study of the electronic and vibrational spectra allowed to explain the important superconducting properties of this class of compounds (K.I. Pokhodnya,M.E. Kozlov). The ways to control and stabilize the superconductivity of BEDT-TTF compounds showed the highest values of critical temperatures, but suffered from dielectric phase transitions (Yu.V. Sushko, M.A. Tanatar,V.A. Bondarenko).
The investigation of quantum-confined structures based on group-IV materials, A2B6 and A3B5 compounds has began in 1994. Namely, it was investigated porousSi,prepared bychemical andanodicetching, as well as silica and alumina layerswith embedded Sinanocrystalsobtained bymagnetronsputtering, structureswith quantum wellsandquantum dotsbasedA2B6 and A3B5 semiconductorsgrownby molecularbeamepitaxyand systems with A2B6 quantum dotsobtainedby methodsof colloidalchemistry.
The study of the structures with Si nanocrystals embedded in oxide matrix revealed the contribution of different channels of radiative recombination (recombination of excitons in Si nanocrystals and recombination through defects in the oxide matrix) in the luminescence spectra on these objects versus fabrication conditions and post fabrication processing, as well as during aging. In particular , the comparison of the structural and luminescent characteristics of Si-rich-SiO2 and Si-rich-Al2O3 layers showed that the formation of Si nanocrystals upon annealing is faster in Si-rich-Al2O3 layers than Si-rich-SiO2 films. At the same time, the luminescence spectrum of Si-rich-SiO2 layers is determined mainly by recombination of excitons in Si nanocrystals, whereas the emission of Si-rich-Al2O3 materials is dominated by carriers' recombination via radiative defects at the interface Si/Al2O3 or oxide matrix (N.O. Korsunska , L.Yu. Khomenkova, T. R.Stara).
Luminescence bands associated with cationic vacancies were identified for epitaxial heterostructures with CdSe/ZnSe quantum dots. It was shown that vacancies are formed during growth process, preventing self-organization of large quantum dots and causing rapid dot dissolution upn annealing due to stimulation of lateral diffusion (L.V.Borkovska, N.O. Korsunska).
For the first time the analytical solution of the system of equations for the model of independent capture of carriers in quantum dots in A2B6 compounds and experimentally confirmed that this model well describes the process of thermal quenching of luminescence in epitaxial structures with CdSe/ZnSe quantum dots. At the same time, it is shown that the thermal quenching of photoluminescence of the structures InAs/InGaAs/GaAs with InAs quantum dots in InGaAs asymmetric quantum well is described by the model of two-stage thermal emission of the excitons from quantum dot to quantum well and from quantum well to GaAs barrier (L.V. Borkovska, N.O. Korsunska).
Mechanisms of spectral shift of the maximum of luminescence band of colloidal quantum dots (CdSe/ZnS core/shell type) conjugated with biomolecules was developed. This effect was proposed to be used for resistration of the presence immuno-complexes and can significantly improve the accuracy immuno fluorestsent analysis (L.V. Borkovska, N.O. Korsunska, L.V. Scherbyna). A new mechanism of the effect photo-stimulated enhancement of luminescence efficiency of colloidal CdSe quantum dots under ultraviolet irradiation was porposed by N.O.Korsunska.
The dependence of the photoluminescence spectra of colloidal CdSe quantum dots embedded in polymer matrix of gelatin and polyvinyl alcohol, on the synthesis conditions was found. It was discovered the possibility for low-temperature control of this transformation upon annealing in air. It is shown that the change in the luminescence spectra of quantum dots during annealing depends on the nature of physical and chemical changes in the polymer matrix at quantum dot/polymer interface. The effect of photo-stimulated enhancement of luminescent emission of CdSe quantum dots, embedded in poly-vinyl alcohol host under visible irradiation was observed (L.V. Borkovska, N.O.Korsunska).
Developments
Most significant scientific and technical developments:
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Method for gas-phase synthesis of single crystals and a number of A2B6 single crystals with perfect crystalline structure was grown (CdS, CdSe, CdTe, ZnO) (B.M. Bulakh , G.S. Pekar, 1966-2003: B.M. Bulakh, A.S. 135227, USSR, 06/01/60; A.S. 209417, USSR, 07/08/66; B.M. Bulakh, G. S. Pekar, A.S. 1678972, USSR, 05/07/71 )
Method for an enhancement of the photosensitivity of A2B6 semiconductor compounds (N.E. Korsunskaya, I.V. Markevich , M.D. Moin , E.A. Sal'kov , A.S. 982487, USSR, 1982). |
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Method for fabrication of ohmic contacts to semiconductors (N.E. Korsunska, M.D. Moin, E.A. Sal'kov, V.D. Fursenko, A.S. 904477, USSR, 1982).
Method for manufacturing of “photoconductor - transparent contact” structures (N.E. Korsunskaya, M.D. Moin , I.Yu. Shabliy, A.S. 982486, USSR, 1982).
Express method of quality control (reliability prediction) of photovoltaic devices based on A2B6 semiconductors, testing the crystals for "photochemical reactions" (N.E. Korsunskaya, T.V. Torchinskaya, M.K. Sheinkman, I.V. Markevich, A.S. 993174, USSR, 1983).
Method of photosensitive elements manufacturing (N.E. Korsunskaya, A. Baidulaeva, I.Ya.Gorodetskiy , P.E. Mozol’, A.S. 1091768, USSR, 1984).
Method for fabrication of photosensitive thin-film hetero-junctions (B.S. Atdaev, B.M. Bulakh , G. Goryagdyev, M.Ya. Rakhlin, M.K. Sheinkman, A.S. 1356917, USSR, 01/08/87)
Method for production of solid solutions of group II metal monochalcogenides by solid phase substitution (B.M. Bulakh, B.L. Druz’, Yu.N. Evtukhov, E.A. Sal'kov, A.S. 1637379, USSR, 4/13/89; B.M. Bulakh, B.L. Druz’, Yu.N. Evtukhov, A.V. Thomson, A.S. 1637378, USSR, 4/13/89)
Method to improve an industrial technology of AlGaAs/GaAs heterostructures for space solar-cell application. The results of the investigation of double GaAlAs-structures were used for fabrication of AL307LM LEDs (Svetlovodsk, Ukraine) (T.V. Torchinskaya).
| Method for fabrication of photosensitive CdS single crystals with low content of extended defects (N.E.Korsunskaya, I.V. Markevich , G.S. Pekar, A.F. Singaevskiy, 1992). Proposed method was applied to grow single CdS crystals with unique high optical strength, low density of dislocations, inclusions and low-angle boundaries . These crystals were used for fabrication of the screens of powerful lasers with electron beam pumping. Proposed technology was implemented at in the NPO "Platan" (Fryazino, Russia) , Research Institute of Materials (Zelenograd, Russia) and PIAS (Moscow, Russia). Patent of Russia, No. 1831894 (N.V. Klimova, N.E. Korsunskaya, I.V. Markevich, G.S. Pekar, A.F. Singaevskiy (1992). | 
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Method of low-temperature express doping and cleaning of A2B6 crystals (I.V. Markevich, N.O. Korsunska, L.V. Borkovska, L.Yu. Khomenkova). | 
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Elaborated technology for fabrication of macro- and nano-porous Si layers with controlled luminescence properties by anodization technique (B.M. Bulakh, 1991-1999). |
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Contactless and non-destructive method for control of spatial distribution of free carrier concentration and compensating impurity in commercial wafers and epitaxial SiC films, based on a comparison of spatial distribution of the intensities of photo- and thermally stimulated luminescence (N.O. Korsunska, 2005).
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Elaborated method for fabrication of undoped and doped with group I elements ZnO and ZnMgO ceramic (I.V. Markevich, T.R. Stara, V.I. Kushnirenko). |
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Method to improve luminescence efficiency of epitaxial CdZnTe/ZnTe structures by adding of thin CdTe layer in CdZnTe quantum well during growth process (N.O. Korsunska , L.V. Borkovska).
| Method for the detection of biomolecules conjugated with colloidal CdSe quantum dots based on the registration of the evolution of luminescence spectra of quantum dots observed upon the deposition of quantum dots’ solution on solid substrate followed by low-temperature annealing (N.E. Korsunska , L.V. Borkovska). | 
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Equipment
- Setup SDL-2 for investigation of photoluminescence spectra (in 220-2000 nm spectral range) and luminescence excitation spectra (in 200-1000 nm spectral range)
- The optical cryostat for the measurements of photoluminescence spectra and optical transmission in 4.2-300K temperature range, equipped with a temperature controller "UTRECS"
- Setup for investigation of the photoluminescence spectra (in 470-2000 nm spectral range) and luminescence excitation spectra (in 200-1000 nm spectral range) with IKS-12 and MDR–23 monochromators;
- Setup for test of electrical parameters of the samples, for investigation of photocurrent and thermally conductivity spectra;
- Setup for gas-phase synthesis of the crystals;
- Setup VUP-5 for the deposition of metal and semiconductor films;
- Setup for measurement of capacitance-voltage (C-V) and current-voltage (I-V) characteristics;
- Setup for investigation of kinetic characteristics of semiconductor compounds (electrical conductivity, Seebeck coefficient, magnitoresistance, Hall coefficient) in 1.3-300K temperature range.
- Setup for the study of electrical conductivity in a wide range of temperatures and hydrostatic pressure (up 15 kbar).
Projects
Project III-4-11 "Photoelectrical, optical and fluctuation phenomena in light-emitting wide band-gap semiconductor compounds, semiconductor structures for micro- and nanoelectronics and development of technological methods for their fabrication" (Head of project: N.O. Korsunska, 2011-2015)
Project № 2.2.1.14-DP "Development of the techniques for the formation of nanostructured objects on the surface of A2B6 semiconductors by chemical etching and colloidal synthesis in solutions, their embedment in solid-state matrix and the study of the optical and electrical properties" in the frame of National scientific-technical program "Nanotechnologies and Nanomaterials" (2010-2014);
Project "Development of fabrication approach and investigation of the properties of zinc oxide layers as a material for white light source" in the frame of program III-10-12 "Development of advanced semiconductor materials and structures for opto-, micro- and sensor electronics" ( 2012 - 2014 );
Project "Improvement of methods of manufacturing luminescent quantum confinement structures based on A2B6 compounds required for optoelectronics and medicine" in the frame of program III-41-12 "The development of technological methods for creation of new functional materials and structures for modern electronics, information technique and sensors" (2012-2014).
Our collaboration in Ukraine:
- L.V. Pisarzhevskiy Institute of Physical Chemistry of National Academy of Sciences of Ukraine;
- Institute of microbiology and genetics National Academy of Sciences of Ukraine;
- National Technical University of Ukraine "KPI";
- Kyiv National Taras Shevchenko University.
Our collaboration with foreign laboratories:
- Center of investigation of Ions, Materials and Photonics (CIMAP) at CNRS (Caen, France) since 2007;
- National Polytechnic Institute (Mexico city, Mexico) since 2000;
- University of South Florida (Tampa, USA) since 1998;
- Racah Institute of Physics, Hebrew University (Jerusalem, Israel) since 1996.