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


Laboratory of physics defects and nonequilibrium processes


Acting Head of Department

Veleschuk Vitaly Petrovych

Ph.D., senior scientist

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Doct.phys.-math. sciences, prof.


Vlasenko Alexandr Ivanovich




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 Z Vlas

Vlasenko Zoya Kostyantinovna

Ph.D., senior scientist

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Gnatyuk Volodymyr Anastasiyovych

Ph.D., Associate professor, senior scientist

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Gentsar Petro Olexiyovich

Ph.D., senior scientist

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Levytskyi Sergiy Nikolayovich

Ph.D., senior scientist

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Main research areas:

  • Nonequilibrium electron processes and transport processes in complex semiconductor materials, including the narrow-gap ones and structures.
  • The processes of defect formation, defect dynamics and mass transfer in complex semiconductors, including the effect of external fields of various physical nature.
  • The processes of acoustic emission in semiconductor materials and structures.
  • The processes of intrinsic and induced by external fields degradation of LED structures, including nanostructures. Creation of methods and means of insitu diagnostics of reliability of light emitting structures.
  • Processes of laser-induced formation of semiconductor barrier and surface nano-sized structures. The creation of radiation sensitive structures for dosimetry and the visualization of hidden objects. Development of methods for imaging extended critical defects in semiconductor structures by microplasma luminescence.


Main results and achievements

Found dominant mechanisms, physical conditions and quantitative criteria competitiveness of different mechanisms of recombination and current transport in crystals CdHgTe depending on their volume and surface parameters; the dominant role in these processes of fluctuations in the level of stoichiometry and composition, inclusions with coherent and incoherent surfaces of the section was found; the mechanisms of natural and induced transformation of defect systems are determined.

In small-size structures based CdHgTe defined physical conditions of competition in the bulk recombination flows and formative surfaces, and depending on the degree of bipolarity and other factors set conditions electrofield extraction process dominance over the processes of recombination of charge carriers and heating; Significant influence and dependence of current transfer parameters on the type and parameters of inhomogeneities were revealed. On the basis of these works the conditions of realization of optimal modes and boundary parameters of infrared photoresistors and SPRITE - structures are determined.

Together with NU Lviv Polytechnic, mechanisms of epitaxy of CdHgTe on substrates of various degrees of conjugation (CdTe, CdMnTe, CdZnTe, Al2O3, GaAs, etc.), orientations, polarity, structural perfection, in particular, adsorption processes, nucleation, coalescence of islets, further growth in dependence were studied from technological conditions. The processes of formation of epitaxial two- and three-dimensional nanostructures of CdHgTe were first discovered and studied. The physical properties and elastic parameters of epitaxial heterosystems, including varisonous The presence of arrays of dislocations of various origin, which, together with residual stresses, leads to an uneven grid structure thickening in thickness.

In varicosed heterosystems, the influence on the recombination processes of the metallurgical boundary of the section, the longitudinal zonal relief, the presence of gradient photoresists of different nature were detected; In polycrystalline layers, the influence on the photoconductivity of geometrical and injection-recombination parameters of grains and intergranular boundaries, which may change with active external actions and natural degradation.

Based on these works created a wide range of small inertia infrared photodetectors - uncooled (for spectral range up to 6 μm) and refrigerated (2-15 μm) broadband and selective (single and multi), including PV with spectral dependence the inversion of the photoresign, which is important for applications in monitoring systems, where it is necessary to separate photos in the spectral bands of the reflection and thermal radiation of objects and inhibition of optical disturbances in other ranges.

Found that complex semiconductors, including A2B6, A3B5, A3 B6, A4 B6, solid solutions and structures based on them compared with elementary more vulnerable to degradation and to external fields of different physical nature (thermal annealing, pulsed laser irradiation and induced elastic and shock waves, ultrasound and g-irradiation, static and dynamic deformations, etc.). It is shown that each of these fields specificity inherent in changing the physical properties of the material, depending on the type and parameters of these fields, individual or selective isotropic mechanisms of action in crystals and is due to restructuring and impurity own point and extended defects. It has been shown that these changes may have a metastable character (with different relaxation times), leading to a temporary indeterminacy state material and unpredictable distortion signal, particularly at its photoelectric conversion, and stable in nature, leading to the irreversible transformation of the structure and can be the cause of the degradation of the material, or is used for directional defect redesign.

The mechanisms of previously unknown processes of natural and induced degradation in these materials and structures have been discovered and established. In binary compounds, the processes of electrical activation (decontamination) of point defects during their reorganization due to the relaxation of residual stresses induced by external fields of local deformation and heating, etc.; In solid solutions (in particular, CdHgTe) - in addition: the processes of decay, spatial stratification of components, their enrichment of individual regions, as well as their precipitation. In the CdTe-Te heterosystems processes of amorphization -crystallization Te are discovered; In light-emitting heterosystems based on GaP, GaAs, GaN, including with quantum wells, in in-situ mode (acoustic emission method) - local processes, incl. plastic, deformation of certain regions of these structures due to the electric-induced inhomogeneity of their heating.

The laser-induced processes of formation, self-organization and ordering in periodic nanosized structures of the surface relief of CdTe, Cd(Me)Te, GaAs, Si were first discovered and studied. Together with the Lomonosov Moscow State University (Russia) developed and determined the quantitative parameters of the plasma-deformation model of these processes.

New physical and technological methods of defect systems management, creation of highly effective instrumental structures with the use of laser pulse, including Shock wave, electrochemical, mechanical, and others. Actions for the formation of potential barriers, stabilization and photosensitivity of the surface and volume. The methods of doping the surface, surface layers, separate layers in the thickness of the material are developed; The formation of barrier (Schottky) and omnitic Me1/Cd(Me2)Te structures, near-surface inversion, varizone and gettering layers, protective coatings; cleaning and passivation of the surface; structuring of polycrystalline structures, etc.

Processes and mechanisms of acoustic emission (AE) in light-emitting structures and light emitting diodes, which occur simultaneously with changes and degradation of their electrical and luminescent characteristics, are revealed.

The complex non-destructive method of diagnostics and rapid control of degradation of LED structures, indicator and power LEDs is created, which allows real-time detection of degradation and relaxation processes at the threshold of AE occurrence. This method includes: 1) the method of acoustic emission, 2) differentiation of CVC and recombination rate, 3) registration of luminescence microplasma (controlled breakdown) and measurement of their parameters. A computerized apparatus for complex simultaneous measurements in semiconductor materials and structures AE, luminescence and electrical characteristics was developed to detect the initial stages of their degradation.

The dominant mechanisms of pulsed laser-induced solid-state masstransfer in CdTe are established for the creation of detector structures and the optimal regimes of the such method of doping are determined.

The method of pulsed laser doping of CdTe indium with irradiation of In/CdTe structures, including in water with photo-thermo-acoustic in-situ control, is developed; As well as a method for determining the threshold of pulsed laser-induced melting of semiconductor crystals, in particular CdTe and GaAs. Diode structures were obtained and high-performance X-ray and gamma radiation spectrometers with low electrical noise, high sensitivity and resolution for hidden object scanning and visualization systems were created. The results are being implemented in the Research Institute of Electronics, Shizuoka University.

Experimental methods of determination and express control of parameters of multicomponent semiconductors, including Narrow-bandedge, in particular, electrical and photoelectric characteristics of volume and surface, composition of material, detection and determination of the type of heterogeneities, deviations from stoichiometry, structural disorder. Measuring devices, devices and installations, including high-sensitivity, low level of own noise for research of electrophysical, optical, photovoltaic, acoustic, physical and mechanical properties of such materials.

{tab Field of Research}



·        Acoustic emission device AF - 15 computerized,

·        An installation for measuring luminescence spectra and photoconductivity on the basis of spectrometers MDR-3 and ICS,

·        Installation for irradiation based on the modern four-mode YAG:Nd pulsed laser LS2131U (LOTIS TII),

·        Ruby and neodymium lasers,

·        Instrument for measuring СМС SourceMeter 2400 (Keithley),

·        Microscope MBS-10 and USB MicroDigital,

·        Installation for spraying metals VUP-4,

·        Soldering station Lukey 898,

·        Oscilloscopes Tektronix TDS 1012 and TDS 2022 nanosecond band


Projects and grants


No 31/ "Acoustic-emission development and creating rapid method for monitoring and predicting the reliability of the semiconductor light-emitting structures", the state scientific and technical program "Development and implementation of energy-saving LED lights and lighting systems based on them" (2008-2013 years)


No II-53/17/8/-N "Physical mechanisms of nanostructures formation on semiconductor surfaces under pulsed laser irradiation" Target complex program of the fundamental research of NAS of Ukraine "Fundamental problems of nanostructured systems, nanomaterials, nanotechnology". (2009-2014 years)


A joint project of universities, research institutions of the National Academy of Sciences and the National Academies of Sciences of Ukraine "State Fund for Fundamental Research of Ukraine-2015-2016", No F64/49 - 2015 and F64/16 - 2016 "Photothermoacoustic conversion and fast mass-transfer in silicon and cadmium telluride at nanosecond laser irradiation" (2015-2016 years)


A joint project of the State Fund for Fundamental Research of Ukraine with the Japan Society for Promotion of Science "SFFR - JSPS - 2016" F68/54-2016 "Development of methods and technology of high-resolution X-ray and gamma radiation detectors based on the semiconductors Cd(Zn)Te for safety and diagnostics devices"(2016-2017 years)


A joint project of State Fund for Fundamental Research of Ukraine "SFFR - BrFFR - 2013" No F54.1/033 "Thermodynamic and kinetic processes of heterosystems modification based on the silicon and cadmium telluride initiated by the intense nanosecond pulses of laser" (2013-2014 years)


A joint project of State Fund for Fundamental Research of Ukraine "SFFR - Japan - 2013" No F52.2/0.15 "High-resolution Cd(Zn)Te detectors for registration X-ray and gamma quanta and imaging" (2013-2014 years).


Joint project of the State Fund for Fundamental Research of Ukraine "SFFR- BrFFR - 2011" No F41.1/032 "Laser-induced by nanosecond pulses mass-transfer processes and the formation of inversion and vary-band layers in solid solutions based on the cadmium telluride" (2011 – 2012 years)


The project of the 7th Framework Program of the European Commission of the European Union No 218000 Cooperation across Europe for Cd(Zn)Te based Security Instruments (COCAE) (2009-2013 years)


Project No 2.1.1/17 "Development and creation of acoustic emission express method for controlling and reliability predicting of the semiconductor materials and structures", State target scientific and technical program "Development and creation of sensor science-intensive products" (2008-2017 years)

Project No 1.2.1/17 "Development and creation of matrices based on the sensor diode structures and device for nuclear radiation detection and their approbation in the radiation safety facilities". State target scientific and technical program "Development and creation of sensor science-intensive products" (2008-2012 years)