The fabrication of Ge(Si) self-assembled islands on Si substrates has attracted much attention in... more The fabrication of Ge(Si) self-assembled islands on Si substrates has attracted much attention in the last several years because of their great potential for practical application. In this paper we present the results of investigations into the growth and optical properties of single and multilayer structures with Ge(Si)/Si(001) self-assembled islands, grown at different Ge deposition temperatures (TGe). It is shown that the sizes and surface density of the islands can be varied in a wide range by altering TGe: from nanometer scale islands for high TGe to small quantum dots with a height of ∼ 1 nm and a surface density of >1011 cm−2. The GeSi alloy formation in islands grown at TGe>580° C was observed by X-ray diffraction, Raman scattering and selective etching. The alloy formation is caused by a strain-driven Si diffusion in islands. The dependence of island composition on TGe was experimentally measured and found to drastically affect the sizes and shapes of the islands.
Macromolecular Materials and Engineering, Feb 19, 2023
Thin polytetrafluoroethylene (PTFE) films are produced by deposition from a gas phase by two meth... more Thin polytetrafluoroethylene (PTFE) films are produced by deposition from a gas phase by two methods: electron‐enhanced vacuum deposition (EVD) and EVD + low‐temperature plasma (LTP). Structure, morphology, and composition of the films are studied by IR spectroscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy. They are close to the structure of bulk PTFE. The roughness of the films’ surface is changed with gas pressure and LTP power variations. Films are transparent from UV to near‐infrared regions. Refractive and extinction indices and their anisotropy are measured by spectral ellipsometry. They are tuned by variations of deposition conditions. Hardness and Young modulus of the films are increased if EVD + low power LTP is used for film deposition. Use of EVD + LTP also increases thermal stability of the films. Contact angle of the films corresponds to the bulk PTFE. The PTFE molecules oriented are preferentially in perpendicular direction to the substrate surface.
The specificity of the test networks for hernia repair using an atomic force microscopy was studi... more The specificity of the test networks for hernia repair using an atomic force microscopy was studied. The method allows to determine the compatibility of allograft material with the body of the patient, and select the appropriate implant support optimal patient after surgery.
Carbon nanoporous thin films are very attractive for application in fields of supercapacitors, fu... more Carbon nanoporous thin films are very attractive for application in fields of supercapacitors, fuel cells, gas sensors and others. However due to it very high resistance an employment of this material for resistance gas sensor is problematic. At the same time graphene based materials are very sensitive to different gas ambient and have a resistivity suitable for testing. In this work the new method of formation of high porous graphite-like thin films by RF magnetron plasma enhanced chemical vapor deposition (MPECVD) from argon-methane/argon-acetylene gas mixture followed by annealing at 650ºC, is suggested. A comparative study of transformation of nanoporous carbon film produced in different carbon-hydrogen atmosphere into graphitic one, their structural and electrical properties are presented. The films of nanoporous carbon were fabricated on silicon or SiO2/Si wafers. To clarify chemical structure of the film FTIR spectroscopy and XPS were used. Micro-Raman spectroscopy and AFM we...
The monograph highlights the results of the scientific topic "Theoretical and practical aspe... more The monograph highlights the results of the scientific topic "Theoretical and practical aspects of the use of mathematical methods and information technology in education and science" (registration number 0116U004625) by the Department of Computer Science and Mathematics, Faculty of Information Technology and Management, Borys Hrinchenko University of Kyiv (deadline: March 2016 - March 2021). The main scientific and practical results in the following areas are presented: mathematical and computer modeling, hardware and software of automated control systems, application of digital technologies in the educational process. For scientific and pedagogical, scientific and pedagogical workers who are interested in modern problems of application of mathematical methods and digital technologies in education and science.
... Zinc oxide analogue of GaN with new perspective possibilities VA Karpina 1 , VI Lazorenko 1... more ... Zinc oxide analogue of GaN with new perspective possibilities VA Karpina 1 , VI Lazorenko 1 , CV Lashkarev* 1 , VD Dobrowolski 1 , LI Kopylova 1 , VA Baturin 2 , SA Pustovoytov 2 , A. Ju. Karpenko 2 , SA Eremin 2 , PM Lytvyn 3 , VP Ovsyannikov 4 , and EA Mazurenko 4 ...
Abstract—The Ti–Al–C and Ti–Al–Si–C films have been deposited on Si(100) substrates by dual DC ma... more Abstract—The Ti–Al–C and Ti–Al–Si–C films have been deposited on Si(100) substrates by dual DC magnetron sputtering of the Ti–Al composite, graphite, and SiC targets at various sputtering currents. The effects of the sputtering current and annealing temperature on the structural, compositional, and mechanical properties of the films have been studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and hardness measurements. The as-deposited films are amorphous and exhibit low values of the root mean square roughness (0.25–0.27 nm). The results of XRD and XPS studies and first-principles calculations confirm that the annealing at 800°C leads to the formation of the crystalline Ti2AlC MAX, Al4C3, TiC2, and TiO2 phases and the amorphous Al–C–O phases, and the crystalline Ti2Si1 – xAlxC MAX, Al4C3, and TiSi/TiSi2 phases and the amorphous Al–Si–C–O phases in the Ti–Al–C and Ti–Al–Si–C films, respectively. The amorphous films exhibit an increase in the hardness with an increase in the sputtering current at the graphite or SiC targets, which reaches maximum values of 19.1 and 17.8 GPa for the Ti–Al–C and Ti–Al–Si–C films, respectively. The observed changes in the hardness are explained by the evolution of chemical bonds.
The formation of GeSn nanostructures catalyzed by Sn surface droplets during the growth of Ge 1-x... more The formation of GeSn nanostructures catalyzed by Sn surface droplets during the growth of Ge 1-x Sn x /Ge/Si (0 0 1) heterostructures provide a promising strategy for the growth of high-quality Sn-containing group-IV alloys. The droplet formation is favored by Sn segregation at dislocation cores and diffusion of Sn towards the sample surface. Subsequent Sn droplet motion along 〈1 1 0〉 crystallographic directions result in self-assembled Ge stripes along the droplet's path. A novel phenomenon is observed, for which Sn-rich GeSn nanowires (NWs) were periodically formed on top of Ge(Sn) stripes. While the front edge of the liquid Sn droplet is continuously moving and dissolving the Ge 1-x Sn x epilayer, the phenomenon of NW periodicity is explained by discrete jumping of the back edge of the droplet resulting in redeposition of material forming the NWs. It is also demonstrated that sninduced phase separation of metastable Ge 1-x Sn x epilayers leads to carrier redistribution and an electric-fieldinduced conductivity type conversion from p-to n-type in the Ge(Sn) stripes. These results advance our understanding of the Sn segregation and phase separation mechanism for Ge 1-x Sn x epilayers at relatively low temperature (≥230 • C). This study could pave the way for understanding the droplet epitaxy synthesis of Sn-rich GeSn nanostructures generating emergent functionalities of GeSn-based nanodevices.
The fabrication of Ge(Si) self-assembled islands on Si substrates has attracted much attention in... more The fabrication of Ge(Si) self-assembled islands on Si substrates has attracted much attention in the last several years because of their great potential for practical application. In this paper we present the results of investigations into the growth and optical properties of single and multilayer structures with Ge(Si)/Si(001) self-assembled islands, grown at different Ge deposition temperatures (TGe). It is shown that the sizes and surface density of the islands can be varied in a wide range by altering TGe: from nanometer scale islands for high TGe to small quantum dots with a height of ∼ 1 nm and a surface density of >1011 cm−2. The GeSi alloy formation in islands grown at TGe>580° C was observed by X-ray diffraction, Raman scattering and selective etching. The alloy formation is caused by a strain-driven Si diffusion in islands. The dependence of island composition on TGe was experimentally measured and found to drastically affect the sizes and shapes of the islands.
Macromolecular Materials and Engineering, Feb 19, 2023
Thin polytetrafluoroethylene (PTFE) films are produced by deposition from a gas phase by two meth... more Thin polytetrafluoroethylene (PTFE) films are produced by deposition from a gas phase by two methods: electron‐enhanced vacuum deposition (EVD) and EVD + low‐temperature plasma (LTP). Structure, morphology, and composition of the films are studied by IR spectroscopy, atomic force microscopy, and X‐ray photoelectron spectroscopy. They are close to the structure of bulk PTFE. The roughness of the films’ surface is changed with gas pressure and LTP power variations. Films are transparent from UV to near‐infrared regions. Refractive and extinction indices and their anisotropy are measured by spectral ellipsometry. They are tuned by variations of deposition conditions. Hardness and Young modulus of the films are increased if EVD + low power LTP is used for film deposition. Use of EVD + LTP also increases thermal stability of the films. Contact angle of the films corresponds to the bulk PTFE. The PTFE molecules oriented are preferentially in perpendicular direction to the substrate surface.
The specificity of the test networks for hernia repair using an atomic force microscopy was studi... more The specificity of the test networks for hernia repair using an atomic force microscopy was studied. The method allows to determine the compatibility of allograft material with the body of the patient, and select the appropriate implant support optimal patient after surgery.
Carbon nanoporous thin films are very attractive for application in fields of supercapacitors, fu... more Carbon nanoporous thin films are very attractive for application in fields of supercapacitors, fuel cells, gas sensors and others. However due to it very high resistance an employment of this material for resistance gas sensor is problematic. At the same time graphene based materials are very sensitive to different gas ambient and have a resistivity suitable for testing. In this work the new method of formation of high porous graphite-like thin films by RF magnetron plasma enhanced chemical vapor deposition (MPECVD) from argon-methane/argon-acetylene gas mixture followed by annealing at 650ºC, is suggested. A comparative study of transformation of nanoporous carbon film produced in different carbon-hydrogen atmosphere into graphitic one, their structural and electrical properties are presented. The films of nanoporous carbon were fabricated on silicon or SiO2/Si wafers. To clarify chemical structure of the film FTIR spectroscopy and XPS were used. Micro-Raman spectroscopy and AFM we...
The monograph highlights the results of the scientific topic "Theoretical and practical aspe... more The monograph highlights the results of the scientific topic "Theoretical and practical aspects of the use of mathematical methods and information technology in education and science" (registration number 0116U004625) by the Department of Computer Science and Mathematics, Faculty of Information Technology and Management, Borys Hrinchenko University of Kyiv (deadline: March 2016 - March 2021). The main scientific and practical results in the following areas are presented: mathematical and computer modeling, hardware and software of automated control systems, application of digital technologies in the educational process. For scientific and pedagogical, scientific and pedagogical workers who are interested in modern problems of application of mathematical methods and digital technologies in education and science.
... Zinc oxide analogue of GaN with new perspective possibilities VA Karpina 1 , VI Lazorenko 1... more ... Zinc oxide analogue of GaN with new perspective possibilities VA Karpina 1 , VI Lazorenko 1 , CV Lashkarev* 1 , VD Dobrowolski 1 , LI Kopylova 1 , VA Baturin 2 , SA Pustovoytov 2 , A. Ju. Karpenko 2 , SA Eremin 2 , PM Lytvyn 3 , VP Ovsyannikov 4 , and EA Mazurenko 4 ...
Abstract—The Ti–Al–C and Ti–Al–Si–C films have been deposited on Si(100) substrates by dual DC ma... more Abstract—The Ti–Al–C and Ti–Al–Si–C films have been deposited on Si(100) substrates by dual DC magnetron sputtering of the Ti–Al composite, graphite, and SiC targets at various sputtering currents. The effects of the sputtering current and annealing temperature on the structural, compositional, and mechanical properties of the films have been studied using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and hardness measurements. The as-deposited films are amorphous and exhibit low values of the root mean square roughness (0.25–0.27 nm). The results of XRD and XPS studies and first-principles calculations confirm that the annealing at 800°C leads to the formation of the crystalline Ti2AlC MAX, Al4C3, TiC2, and TiO2 phases and the amorphous Al–C–O phases, and the crystalline Ti2Si1 – xAlxC MAX, Al4C3, and TiSi/TiSi2 phases and the amorphous Al–Si–C–O phases in the Ti–Al–C and Ti–Al–Si–C films, respectively. The amorphous films exhibit an increase in the hardness with an increase in the sputtering current at the graphite or SiC targets, which reaches maximum values of 19.1 and 17.8 GPa for the Ti–Al–C and Ti–Al–Si–C films, respectively. The observed changes in the hardness are explained by the evolution of chemical bonds.
The formation of GeSn nanostructures catalyzed by Sn surface droplets during the growth of Ge 1-x... more The formation of GeSn nanostructures catalyzed by Sn surface droplets during the growth of Ge 1-x Sn x /Ge/Si (0 0 1) heterostructures provide a promising strategy for the growth of high-quality Sn-containing group-IV alloys. The droplet formation is favored by Sn segregation at dislocation cores and diffusion of Sn towards the sample surface. Subsequent Sn droplet motion along 〈1 1 0〉 crystallographic directions result in self-assembled Ge stripes along the droplet's path. A novel phenomenon is observed, for which Sn-rich GeSn nanowires (NWs) were periodically formed on top of Ge(Sn) stripes. While the front edge of the liquid Sn droplet is continuously moving and dissolving the Ge 1-x Sn x epilayer, the phenomenon of NW periodicity is explained by discrete jumping of the back edge of the droplet resulting in redeposition of material forming the NWs. It is also demonstrated that sninduced phase separation of metastable Ge 1-x Sn x epilayers leads to carrier redistribution and an electric-fieldinduced conductivity type conversion from p-to n-type in the Ge(Sn) stripes. These results advance our understanding of the Sn segregation and phase separation mechanism for Ge 1-x Sn x epilayers at relatively low temperature (≥230 • C). This study could pave the way for understanding the droplet epitaxy synthesis of Sn-rich GeSn nanostructures generating emergent functionalities of GeSn-based nanodevices.
International Frequency Sensor Association Publishing, 2021
So called diluted magnetic semiconductors (DMS) are solid solutions of the magnetic d-transition ... more So called diluted magnetic semiconductors (DMS) are solid solutions of the magnetic d-transition metals in diamagnetic semiconductors. In the transition metals (Mn, Ni, Co, Fe, etc.) the outer shell of the atoms is not completely filled with electrons which determines the magnetic moment of the atom. DMS are promising for use in spintronics in which, unlike conventional electronics, it is possible to use two degrees of freedom of an electron, connected with its charge and spin.
У монографії висвітлено результати опрацювання наукової теми «Теоретичні та практичні аспекти вик... more У монографії висвітлено результати опрацювання наукової теми «Теоретичні та практичні аспекти використання математичних методів та інформаційних технологій в освіті і науці» (реєстраційний номер 0116U004625) кафедрою комп’ю-терних наук і математики Факультету інформаційних технологій та управління Київського університету імені Бориса Грінченка (термін виконання: березень 2016 р. — березень 2021 р.). Представлено основні наукові та практичні результати з таких напрямів: математичне та комп’ютерне моделювання, апаратно-програмні засоби автоматизованих систем керування, застосування цифрових технологій в освітньому процесі. Для науково-педагогічних, наукових і педагогічних працівників, які цікавляться сучасними проблемами застосування математичних методів і цифрових технологій в освіті й науці.
This chapter reviews main results obtained on mirror-like samples made of several grades of bulk ... more This chapter reviews main results obtained on mirror-like samples made of several grades of bulk metallic glasses (BMG). Experiments were carried out under simulated conditions typical for the operation of plasma facing in-vessel mirrors of optical plasma diagnostics in fusion reactor ITER. Bombardment with D 0 and T 0 atoms radiated from burning plasma was predicted to be the main reason for the degradation of optical properties of such mirrors. Therefore, to simulate the behavior of mirrors in ITER, mirror-like samples were subjected to bombardment by ions of deuterium plasma with fixed or wide energy distribution. The effects of ion bombardment on optical properties, development of roughness, uptake of deuterium, appearance of blisters, and manifestation of some chemical processes are presented and discussed.
Монография посвящена актуальной проблеме восстановительной хирургии. В ней собраны, упорядочены и... more Монография посвящена актуальной проблеме восстановительной хирургии. В ней собраны, упорядочены и проанализированы все данные, которые были известны только узким специалистам в различных областях знаний, рассматриваются патофизиологические причины возникновения реакции организма на искусственные имплантаты. Для описания этих процессов использовались современные физические и биохимические методики. Характеристика поверхности имплантатов сканирующим электронным микроскопом (СЭМ) и, особенно, использование атомно-силового микроскопа (АСМ) показали, что существует влияние имплантатов на организм реципиента и его можно выразить в физических единицах – нано Ньютонах. Благодаря этому предлагается новый алгоритм дооперационной подготовки пациентов. Монография является единственным образцом работы, где описаны патофизиологические процессы между инородным телом и тканями организма на наноуровне с использованием междисциплинарного подхода к решению важной проблемы. Монографія присвячена актуальній проблемі відновлювальній хірургії. У ній зібрані, впорядковані і проаналізовані усі дані, які були відомі тільки вузьким фахівцям в різних галузях знань, розглядаються патофізіологічні причини виникнення реакції організму на штучні імплантати. Для опису цих процесів використовувалися сучасні фізичні і біохімічні методики. Характеристика поверхні імплантатів скануючим електронним мікроскопом(СЕМ) і, особливо, використання атомно-силового мікроскопу (АСМ) показали, що існує вплив імплантатів на організм реципієнта і його можна виразити у фізичних одиницях - нано Ньютонах. Завдяки цьому пропонується новий алгоритм в доопераційної підготовки пацієнтів. Монографія є зразком роботи, де описані патофізіологічні процеси між чужорідним тілом і тканинами організму на нанорівні з використанням міждисциплінарного підходу до вирішення важливої проблеми.
For a wide range of semiconductors (GaAs, GaP, InP, InSb, CdxHg1-xTe, SiC), as well as contact st... more For a wide range of semiconductors (GaAs, GaP, InP, InSb, CdxHg1-xTe, SiC), as well as contact structures based on them, that are of importance in engineering, the mono-graph gives, in a systematized and generalized form, the results of investigation of their properties modification under action of high-power microwave radiations and nanosecond laser pulses. The physical models for production, annihilation and annealing of point defects and impurity-defect complexes in irradiated materials are considered. An analysis is made of the features of radiation-stimulated mass transport, chemical reactions, formation of new phases in various contact structures, and they are related to the parameters of surface-barrier structures. Much space is given to the elastic stress relaxation due to microwave radiation, depending on the initial impurity-defect condition of materials, their surface morphology and irradiation mode. The authors substantially lean on their own experience in this area. They pay special attention to the use of microwave and laser processing of semiconductor materials for improvement of their structural perfection and development, on their basis, of ohmic and barrier contacts having improved parameters. The monograph is intended for researchers and specialists engaged in semiconductor electronics. It may be of use also to lecturers, post-graduates and undergraduates dealing with the above problems.
This overview presents a common approach of practical atomic force microscopy (AFM) diagnostic of... more This overview presents a common approach of practical atomic force microscopy (AFM) diagnostic of surfaces at the sub-micrometer and nano-meter levels. A common metrological model of AFM and sources of uncertainty of measurements are analyzed. Procedures for scanner and tip calibration are presented. Application of precise topometry concerning geometrical sizes of surface features and its metrological traceability are illustrated using original data of systematic AFM diagnostics applied to semiconductor nano-structures with quantum dots grown by molecular beam epitaxy. A number of weighty results important to understand physics of processes during structural ordering in low-dimensional semiconductor systems has been described. Physical, methodological and experimental parts have been presented without extended details that could be found in the complete list of references.
The monograph deals with the physico-technological aspects of interaction of microwave radiation ... more The monograph deals with the physico-technological aspects of interaction of microwave radiation with semiconductor materials and device struc-tures made on their basis. The effect of active actions (microwave treatment, 60Со g-irradiation and rapid thermal annealing) on the processes of structural relaxation in the ТіВ2–GaAs (InP, GaP, SiC) contacts is considered. An analysis is made of the features of the effect of microwave and 60Со g-radiation on the electrical characteristics of resonant tunneling diodes made on the basis of AlGaAs–GaAs heterojunctions, as well as gallium arsenide tunnel diodes with a d-layer in the space-charge region. The experimental data on the effect of microwave radiation on defect modification in the SiO2–GaAs (SiC) structures are presented. The effects in the nanocrystalline silicon–silicon systems induced by microwave radiation are considered. Much space is given to the effects produced by microwave and 60Со g-irradiation in the Та2О5–Si structures, depending on the conditions of Та2О5 formation. The monograph is intended for researchers and those engaged in development of microwave devices. It may be of use also to post-graduates and undergraduates specializing in the corresponding areas.
Arrays of ZnO nanowires are grown by the vapor-liquid-solid method on a silicon substrate. The re... more Arrays of ZnO nanowires are grown by the vapor-liquid-solid method on a silicon substrate. The results of XRD, SEM, and AFM studies show that the diameters of nanowires vary in the range (50-300) nm, and their length is up to 40 $\mu$m. The wires exhibit bright photoluminescence: the band corresponding to the near band edge region and one or two (depending on the growth conditions) defect-related bands. The intensity ratio of the bands reflects the non-stoichiometry of the material and can be controlled by the zinc evaporation temperature and the temperature in the growing zone. {\textcopyright} 2012.
Electron-beam treatment the glass substrates for sensitive elements of SPR devices causes almost ... more Electron-beam treatment the glass substrates for sensitive elements of SPR devices causes almost two-fold narrowing their refractometric characteristics from 0.867 down to 0.453 deg. The angular shift was also changed, which made the measuring range wider by 0.37 deg. The sensitivity of SPR devices increased by 1.7 times from 1.425 up to 2.396 deg–1 as a consequence of lowering the energy expenses during propagation of surface plasmons along the boundary “metal–air”. The reason for this lowering is related to higher surface uniformity of the gold metal film, its higher density as well as lower nano-roughness of the glass surface and the thickness of heterointerface “gold–air”. In this case, the dispersion value for unevenness heights on the surface relatively to the base line was lowered from ±18 down to ±5 nm, mean-square roughness was three-fold reduced from 4.67 down to 1.64 nm, and the thickness of heterointerface gold–air was lowered from 3.26 down to 1.37 nm. It was ascertained using X-ray reflectometry that the film density increased from 17.2 up to 19.3 g/cm3 and reached the value typical for the bulk gold. It provided the changes in the refraction index and extinction coefficient of the gold film, which was ascertained using the ellipsometric method. Thus, the performed analysis of refractometric characteristics showed that electron-beam treatment the glass substrates of sensitive elements for SPR devices is able to efficiently enhance their sensitivity and to widen the range of measured resonance SPR angles.
For the first time, ZnS:Cu films with an intense photoluminescence were prepared by a chemical no... more For the first time, ZnS:Cu films with an intense photoluminescence were prepared by a chemical nonvacuum method. They were produced by means of the combined pyrolytic deposition of zinc and copper dithiocarbamates onto glass and ceramic substrates heated up to 260-300°C. A close packing of practically identical grains is characteristic of these films, with grain sizes depending on the substrate type. The photoluminescence and electroluminescence spectra include the blue, green, and yellow bands typical of copper. The band-intensity ratio depends on the film-preparation conditions, as well as on their excitation, which makes it possible to change the emission color of radiators in a wide range (from blue to white). {\textcopyright} 2000 MAIK "Nauka/Interperiodica".
Graphene oxide films were formed using the ultrasonic spray coating method and studied with micro... more Graphene oxide films were formed using the ultrasonic spray coating method and studied with micro-Raman spectroscopy, atomic force microscopy, and electrical dynamic response of resistance measurements. Effect of different gases (water vapor, ethanol, acetone, ammonia, and isopropyl) on the dynamic response of resistance of the Au / graphene oxide / Au structure has been studied. The dynamic response shows that adsorption of all mentioned gases results in increase of the resistance. For ethanol, acetone and isopropyl adsorption and desorption cycles are almost identical. At the same time, in the case of water vapor and ammonia the cycle of desorption is very week, especially for the former, which attests different mechanisms of adsorption/desorption processes regarding to ethanol, acetone and isopropyl. The mechanisms of studied vapors adsorption/desorption are proposed.
Zinc oxide due to specific electrical, optical and acoustic properties is the important semicondu... more Zinc oxide due to specific electrical, optical and acoustic properties is the important semiconductor material, which has many various applications. There is growing interest in ZnO due to its potential applicability for optoelectronic devices such as light-emitting diodes, laser diodes and detectors for UV wavelength range. ZnO properties are very close to those of widely recognized semiconductor GaN. The band gap of ZnO (3.37 eV) is close to that of GaN (3.39 eV) but ZnO exciton binding energy (60 meV) is twice larger than that of GaN (28 meV). Optically pumped UV lasing have been demonstrated at room temperature using high textured ZnO films. The excitonic gain close to 300 cm-1 was achieved. ZnO thin films are expected to have higher quantum efficiency in UV semiconductor laser than GaN. The physical properties of ZnO are considered. PEMOCVD technology was used to deposit piezoelectric and highly transparent electroconductive ZnO films. Their properties are discussed. The experiments on polycrystalline ZnO films deposited by RF magnetron sputtering at different partial pressure of oxygen are presented. AFM images were studied in tapping mode for deposited films. The investigated films were dielectric ones and had optical transparency within 65-85% at thickness in the interval 0.2-0.6 $\mu$m. {\textcopyright} 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
\textcopyright} 2016 Optical Society of America. The method of magnetic force microscopy was used... more \textcopyright} 2016 Optical Society of America. The method of magnetic force microscopy was used to study the domain structure of various-thickness epitaxial Y2.95La0.05Fe5O12 iron-yttrium garnet films modified by high-dose implantation of N+ nitrogen ions. The results of multi-crystal x-ray diffractometry were analyzed, and a possible defect structure of garnets prior to and after implantation was identified. It was established that the reduction of magnetic losses observed after high-dose ion implantation is accompanied by the essential ordering of magnetic domains on the surface of implanted films. There is a direct dependence of electromagnetic properties on the dose of implanted atoms followed by a considerable sputtering and amorphization of the near-surface film layer and formation of a well-defined electromagnetic structure.
Mechanism of charge transport in a diode of a silicon carbide's Schottky barrier formed by a quas... more Mechanism of charge transport in a diode of a silicon carbide's Schottky barrier formed by a quasi-amorphous interstitial phase TiBx on the surface of n-6H-SiC (0001) single crystals with an uncompensated donor (nitrogen) concentration of $\sim$1018 cm-3 and dislocation density of $\sim$(106-108) cm-2 has been studied. It is demonstrated that, at temperatures T ≲ 400 K, the charge transport is governed by the tunneling current along dislocations intersecting the space charge region. At T > 400 K, the mechanism of charge transport changes to a thermionic mechanism with a barrier height of $\sim$0.64 eV and ideality factor close to 1.3. {\textcopyright} Pleiades Publishing, Ltd., 2009.
Surface morphology of microsize defects on the surface of various high-index GaAs substrates was ... more Surface morphology of microsize defects on the surface of various high-index GaAs substrates was investigated using an atomic force microscope (AFM). The surfaces investigated were the top layer of 1- and 17-period In0.45GaAs0.55/GaAs structures with quantum dots or buffer layer. These structures were characterized by the formation of oval defects on (1 0 0) surfaces, and microsize defects possessing the shape of multifaceted pits and hillocks on (N11)A/B(N=7,5,4,3) surfaces. The microsize defects were found to chaotically distribute on the surface and, as a rule, gathering in groups with some number of defects. Their density did not depend on the substrate orientation while the shape and orientation of the microsize defects were found to depend on the crystallographic orientation of the substrate. This dependence was determined to be the result of anisotropy of surface diffusion and surface elastic properties. The anisotropy of elastic properties of high-index surfaces was found to be the dominating factor in determining the microsize defect shape. We also report direct evidence of the fact that the effect of quantum dot lateral ordering observed on high-index (N11)B surfaces is determined by the anisotropy of surface elastic properties as well as elastic interaction between adjacent quantum dots. {\textcopyright} 2005 Elsevier B.V. All rights reserved.
Protective coatings of the Ti-Al-Si-N system have been deposited from vacuum arc by sputtering a ... more Protective coatings of the Ti-Al-Si-N system have been deposited from vacuum arc by sputtering a cathode of composition 78Ti-16Al-6Si1 in nitrogen. The coatings of the Ti-Al-Si-N system have been studied using X-ray diffraction analysis to examine phase compositions and substructure, atomic force microscopy to analyze the topography, X-ray fluorescence to define the chemical composition, and nanoindentation to measure hardness and elastic modulus. It has been found that as the nitrogen pressure in the deposition chamber increases, in the Ti-Al-Si-N system the transition from nanocrystalline (to 0.04 Pa) to nanocomposite (0.04-0.66 Pa) and X-ray amorphous (0.66-1.1 Pa) coatings takes place, and at a pressure of 2.7 Pa, the amount of the crystalline phase abruptly increases again. The highest mechanical characteristics and thermal stability have been shown by a coating having the nanocrystalline structure and nanocomposite coatings with a low content of amorphous phase, whose hardness attains 47 GPa. {\textcopyright} 2013 Allerton Press, Inc.
A thermally stimulated structural transformation of the Si-O phase in the SiOx layers, which lead... more A thermally stimulated structural transformation of the Si-O phase in the SiOx layers, which leads to the formation of Si nanoinclusions, was investigated using gravimetry, infrared spectroscopy, multiple-angle ellipsometry, and atomic-force microscopy. It is demonstrated that vacuum heat treatment leads to an increase in the concentration of O bridges in the structural network of oxide. Oxide is compacted, and its surface roughness is smoothened. Silicon and SiO2 phases are precipitated due to the transfer of O atoms from lightly oxidized molecular clusters (SiOSi3) to heavily oxidized ones (SiO3Si). An analysis of ellipsometry data in the context of the effective medium model made it possible to estimate the fractions of the precipitated Si and SiO2 phases. {\textcopyright} 2003 MAIK "Nauka/Interperiodica".
Rare earth metals, when deposited and oxidized on semiconductor surfaces, can be an alternative t... more Rare earth metals, when deposited and oxidized on semiconductor surfaces, can be an alternative to unstable compounds of alkali metals while creating stable and effective emitters with a low work function. A procedure giving rise to the adsorption of Gd and O atoms on the Si(100) surface and the formation of a Si-Gd-O film with a work function of about 1 eV in the near-surface region is described. The films have been studied using the Auger electron and photoelectron spectroscopy, as well as X-ray diffraction, atomic force and Kelvin probe force microscopy techniques. Information about their electronic properties, structure, surface morphology, and surface distribution of potential was obtained. The main component of the film formed on the Si surface is a polycrystalline Gd2O3 phase, which plays the role of a matrix containing textured microcrystallites of one of the following phases: SiO2, GdO2, or GdSi2. The film surface consists of salient clusters 20nm to 80nm in diameter and up to 20nm in height, as well as craters up to 90nm in depth. The surface relief inhomogeneities correlate with the surface distribution of the local work function. This correlation can also be a result of the piezoelectric effect in the strained crystallites of the textured phase located in the bulk of the film. The obtained system was stable in time under vacuum conditions and heating up to 600°C. The method proposed for the formation of surfaces with a low work function making use of rare earth metals can be applied to create effective and stable electron emitters.
Abstract: The effect of the excitation of surface plasmon polaritons at the silver–chalcogenide g... more Abstract: The effect of the excitation of surface plasmon polaritons at the silver–chalcogenide glass interface upon the photostimulated diffusion of silver into chalcogenide was studied for the first time. A high-frequency aluminum diffraction grating with a period of 248.5 nm and a deposited two-layer Ag–As2S3 structure was used to excite plasmons. The process of photostimulated diffusion of silver into the chalcogenide layer is accelerated (that is, the photosensitivity of such a structure increases) when a surface plasmon polariton is excited during exposure at the Ag–As2S3 interface. The photostimulated changes in the optical characteristics of the structure, including at the initial stage of the photodiffusion process, were monitored by recording the dynamics of changes in the characteristics of plasmon excitation with exposure time.
Near-infrared photoresponse is observed in the temperature range of 77-300 K for a photodetector ... more Near-infrared photoresponse is observed in the temperature range of 77-300 K for a photodetector fabricated from undoped In0.35 Ga0.35 As0.35 multiple quantum dots grown in a molecular beam epitaxy system. The detectivity is estimated to be on the order of 3.70 × 109 and 2.70 × 107 cm {\textperiodcentered} √ Hz/W at 77 and 300 K, respectively. The reduction of the detectivity is attributed to the increase of the dark current as the temperature is increased. The photoresponse is explained in terms of several interband transitions. These transitions are found to be in good agreement with the self-consistent theoretical calculations. {\textcopyright} 2008 IEEE.
The effect of rapid thermal treatment at T = 1000°C on the formation of TiBx-n-SiC6H(0001̄) barri... more The effect of rapid thermal treatment at T = 1000°C on the formation of TiBx-n-SiC6H(0001̄) barrier contacts and Ni-n-SiC6H(0001) ohmic contacts was studied. In the former case, thermal treatment neither disturbs the layer structure nor reduces the thermal stability of the barrier contacts. The rapid annealing of an Ni-n-SiC6H(0001) structure results in the formation of a stable ohmic contact. At the same time, this treatment does not change the parameters of the static current-voltage characteristics of the Au-TiBx-n-SiC6H(0001̄) Schottky diodes. These thermally stable diodes are characterized by a sensitivity of ̃3300-3500 mV/mW at an incident radiation power of 10-7 W and are capable of operating at a microwave power of up to 1 W. The dynamic range of a linear portion of the conversion characteristic reaches up to 50 dB. {\textcopyright} 2003 MAIK "Nauka/Interperiodica".
The effect of electron beam irradiation on the structure and doping of the graphene film located ... more The effect of electron beam irradiation on the structure and doping of the graphene film located on the silicon dioxide substrate is investigated, and its influence on carrier transport mechanism is discussed. Local potential measurements have shown that the graphene layer synthesized by CVD method on Cu foil has a granular structure with the grain size of about 3-5 $\mu$m. Micro-Raman analysis along the graphene film between the metal contacts demonstrates that at low doses electron beam irradiation leads to the generation of an additional positive charge in the silicon dioxide layer, which results in fluctuations of the graphene film doping that, in turn, considerably decreases electrical conductivity of graphene. Further increase of electron beam irradiation dose leads to formation of structural defects directly in the graphene layer in addition to doping fluctuations.
The influence of growth conditions to the magnetic microstructure and the parameters of the stres... more The influence of growth conditions to the magnetic microstructure and the parameters of the stress state of LaGa-substituted yttrium iron garnet epitaxial films is analysed. As proved, there are two magnetically nonequivalent tetra-coordinated positions of Fe3+ions with different values and orientations of effective magnetic fields on nuclei for an unsubstituted YIG/GGG film. The appearance of these fields is due to a violation of the anion sublattice stoichiometry and an introduction of impurity atoms into the crystal structure from a melt solution during the growth process. The quantitative characteristics of the dipole-dipole interaction between the 57Fe nuclei in the garnet structure are obtained experimentally if the Ga3+ ions appear in their immediate surroundings. In addition, the change in the orientation of the resulting magnetization vector depending on the magnitude of the diamagnetic substitution is observed. As found, the relatively higher values of period of a stripe domain structure are typical for films with relatively higher values of the component ϵzz of the strain tensor when the compression stresses prevails. As established, the increasing of the domain structure period is observed for samples grown at values of the degree of supercooling of $\Delta$? = 23-24 K. The phenomenological model of the interconnection of the stress state of films and the parameters of its domain structure is proposed.
Chemical and phase composition, magnetic susceptibility, SIMS, magnetic force microscopy, and neu... more Chemical and phase composition, magnetic susceptibility, SIMS, magnetic force microscopy, and neutron diffraction data for Ge1-x-y Snx Mny Te, InSe〈Mn〉, and ZnO〈Co, Mn〉 single crystals are investigated over a wide range of temperatures and magnetic fields. For Ge1-x-y Snx Mny Te the existence of ferromagnetic (FM) ordering with a Curie temperature TC ∼50 K, due to an indirect exchange interaction between Mn ions via the degenerate hole gas, is established. It is shown that at T<50 K the ferromagnetic regions of the crystal form a spin-glass phase. In InSe〈Mn〉 it is found that hysteresis loops of the magnetic moment M (H) are observed up to 350 K. They attest to the existence of ferromagnetic ordering, which is apparently due to ferromagnetic clusters in which a superexchange of the Mn ions via the Se anions is proposed, and to an indirect interaction via the 2D electron gas. At T<70 K a period doubling of the magnetic sublattice of $\alpha$-MnSe second-phase inclusions is observed, and their distribution in the layered structure of the InSe〈Mn〉 host matrix has a regular character, forming a self-organized FMAFM superlattice. In ZnO〈Co, Mn〉 the temperature dependence of M obeys a Curie law. When the solubility limit of Co in ZnO is exceeded, hysteresis loops are observed as a consequence of the appearance of a ferromagnetic second phase. In ZnO〈Mn〉 samples and also in some ZnO〈Co〉 samples with Co content below the solubility limit an antiferromagnetic (AFM) interaction takes place. {\textcopyright} 2009 American Institute of Physics.
Multifractal (MF) analysis is applied for the description of spatial nanoforms which form a relie... more Multifractal (MF) analysis is applied for the description of spatial nanoforms which form a relief on a surface of heterostructures of ZnxCd1-xTe solid solution – substrate Si (1 1 1) synthesized by the method of the electron beam with the evaporating anode. The input data for the MF analysis were the AFM (atomic force microscopy) images of the surface of layers. Comparison of parameters of MF spectrums for different geometries of the surface relief of the layers obtained at identical temperatures and approximately identical growth rates by the above mentioned method of growth and the method of hot wall epitaxy has been performed. It was shown that within the error limits, MF spectrums of spatial nanoforms for heterostructures ZnxCd1-xTe – Si remained very similar under identical conditions for synthesis of layers for compared techniques.
The radiation resistance of Au-Pd-Ti-Pd-n++-InP ohmic contacts and Au-TiBx-n-n+-n++-InP barrier c... more The radiation resistance of Au-Pd-Ti-Pd-n++-InP ohmic contacts and Au-TiBx-n-n+-n++-InP barrier contacts-both initial and subjected to a rapid thermal annealing and irradiated with 60Co $\gamma$-ray photons with doses as high as 109 R-has been studied. Before and after external effects, the electrical characteristics of the barrier and ohmic contacts, distribution profiles for components, and phase composition in the metallization layers have been measured. In ohmic Pd-Ti-Pd-Au contacts subjected to rapid thermal annealing and irradiation, a significant distortion of the layered structure of metallization occurs; this distortion is caused by the thermal and irradiation-stimulated transport of Pd over the grain boundaries in polycrystalline Ti and Au films. However, the specific contact resistance $\rho$c does not change appreciably, which is related to a comparatively unvaried composition of the contact-forming layer at the Pd-n+-InP interface. In the initial sample and the sample subjected to the rapid thermal annealing at T = 400°C with the Au-TiBx-n-n+-n++-InP barrier contacts and irradiated with the dose as high as 2 × 108 R, a layered structure of metallization is retained. After irradiation with the dose as high as 109 R, in the samples subjected to a rapid thermal annealing at T = 400°C, the layered structure of metallization becomes completely distorted; however, this structure is retained in the initial sample. The electrical properties of the contact structure appreciably degrade only after irradiation of the sample preliminarily subjected to a rapid thermal annealing at T = 400°C. {\textcopyright} 2010 Pleiades Publishing, Ltd.
Theoretical and practical aspects of the use of mathematical methods and information technology i... more Theoretical and practical aspects of the use of mathematical methods and information technology in education and science /Abramov, Vadym Astafieva, Mariia Boiko, Mariia Bodnenko, Dmytro Bushma, Aleksandr Vember, Viktoriia Hlushak, Oksana Zhyltsov, Oleksii Ilich, Liudmyla Kobets, Nataliya Kovaliuk, Tetiana Kuchakovska, Halyna Lytvyn, Oksana Lytvyn, Peter Mashkina, Irina Morze, Nataliia Nosenko, Tetiana Proshkin, Volodymyr Radchenko, Serhii Sablina, Milana Semenikhina, Olena Semeniaka, Svitlana Skorobreshchuk, Halyna Khoruzha, Liudmyla Yaskevych, Vladyslav У монографії висвітлено результати опрацювання наукової теми «Теоретичні та практичні аспекти використання математичних методів та інформаційних тех- нологій в освіті і науці» (реєстраційний номер 0116U004625) кафедрою комп'ю- терних наук і математики Факультету інформаційних технологій та управління Київського університету імені Бориса Грінченка (термін виконання: березень 2016 р. — березень 2021 р.). Представлено основні наукові та практичні результати з таких напрямів: математичне та комп'ютерне моделювання, апаратно-програмні засоби автома- тизованих систем керування, застосування цифрових технологій в освітньому процесі. Для науково-педагогічних, наукових і педагогічних працівників, які цікав- ляться сучасними проблемами застосування математичних методів і цифрових технологій
RF hydrogen plasma treatment, rapid thermal annealing and thermal annealing of high-dose implante... more RF hydrogen plasma treatment, rapid thermal annealing and thermal annealing of high-dose implanted amorphized p-type Ge layers have been studied by Raman scattering spectroscopy, AFM, SIMS and electrochemical capacitance-voltage profiling. It is shown that low-temperature RF plasma treatment at temperature about 200 °C results in full recrystallization of thin amorphous Ge layer implanted by P+ ions and activation of implanted impurity up to 8 × 1019 cm -3 with maximum concentration about 20 nm in depth from surface. Rapid thermal annealing (15 sec) and thermal annealing (10 min) in nitrogen ambient demanded considerably higher temperatures for recrystallization and activation processes that resulted to diffusion of implanted impurity inside of the Ge bulk. Mechanisms of enhanced modification of the subsurface implanted Ge layer under plasma treatment are analyzed.
We demonstrate experimentally, that hydrocarbon (CH) films obtained as result of snuff effect in ... more We demonstrate experimentally, that hydrocarbon (CH) films obtained as result of snuff effect in a residual atmosphere of electron scanning microscope under electron beam on amorphous SiO2 surface possess useful properties for microdevices creation, namely: 1) micropattern of CH film is determined by electron beam raster, 2) locally suited axial-symmetric CH films can be obtained by no moving electron beam, 3) thickness of CH film influences on liquid crystal orientation, 4) take place the influence of electron beam movement features on orientation of liquid crystal, 5) CH films demonstrate bistable behavior of nematic.
In the work the testing method of p-n junctions on silicon surface and protective silicon oxide f... more In the work the testing method of p-n junctions on silicon surface and protective silicon oxide film in liquid crystal cell is considered. It has been shown that p-n junctions and defects of SiO2 can be visualized by 1)pseudo-coloration change due to birefringence retardation; 2)deformation of homeotrop nematic with $\Delta$e > 0 due to charge accumulation; 3)depletion and/or enrichment of Si surface induced by ion charge in liquid crystal layer.
We present the results of our research into morphological and electrical properties of ZrBx-n-SiC... more We present the results of our research into morphological and electrical properties of ZrBx-n-SiC 6H and Au-ZrBx-n-SiC 6H surface-barrier structures. They were studied both before and after a 90 s rapid thermal annealing (RTA) in vacuum at the temperature T=1000°C. The ZrBx films were obtained using magnetron sputtering from pressed targets of stoichiometric composition. It was shown that the RTA changed neither contact layered structure nor the abrupt character of the interface, and the contact barrier properties were retained. For the initial (pre-RTA) samples the Schottky barrier height $\phi$B was 0.69-0.78 eV; post-RTA, it became 0.59-0.70 eV.
The paper describes emission properties of a new nanostructured material -carbon-rich amorphous s... more The paper describes emission properties of a new nanostructured material -carbon-rich amorphous silicon carbide (a-SiC) deposited on silicon wafer. Proposed material technology demonstrates that the field enhancement factor of the electron emission of this material can reach 1000 with the current density of about 1x10-3A/cm2 and efficiency of electron emission $\sim$10%. A good correlation between the charge transfer through the a-SiC layer and electron emission from the material in high vacuum is observed. {\textcopyright} (2014) Trans Tech Publications, Switzerland.
We demonstrate experimentally, that in residual atmosphere of scanning electron microscope the na... more We demonstrate experimentally, that in residual atmosphere of scanning electron microscope the nano-scale carboncontaining (hydrocarbon) films by snuff effect can be produced. The micropattern of carbon film including axial-symmetric ones is defined by the e-beam raster. The areas of alignment of liquid crystal molecules precisely repeat the micropattern of carbon containing films with micron resolution. Liquid crystal 5CB on CH film demonstrates a breaking anchoring under simultaneous action of the ac voltage and liquid crystal material flow. AFM analysis of CH films obtained by electron beam enables to conclude that there exists the direction which defines the azimutal alignment of liquid crystal molecules on CH surface.
Investigation of the structure of graphene layers onto silicon dioxide and its relations with car... more Investigation of the structure of graphene layers onto silicon dioxide and its relations with carriers transport mechanism is reported. It has been shown that CVD graphene has granular structure. Potential barriers at the grain boundaries hinder the transport of carriers. Experimental result shows, that electron beam irradiation leads to injection of extra charges into silicon dioxide layer, creating new centers of scattering. It has been found, that conductivity of CVD graphene onto silicon dioxide substrate has not linear character in RF range.
Films of nanosized composites of poly(N-epoxypropylcarbazole) (pEPC) and poly(3,6-di-Br-N-epoxypr... more Films of nanosized composites of poly(N-epoxypropylcarbazole) (pEPC) and poly(3,6-di-Br-N-epoxypropylcarbazole) (pdBEPC) with vanadium pentoxide (V 2O5) are produced for the first time ever. The electroconduction in dark and when illuminated, absorption spectra, steady-state photoluminescence spectra, and time-resolved photoluminescence spectra for the composite films are studied. The results are compared with relevant data for the pEPC, pdBEPC, and V2O5films. A conclusion about the formation of donor-acceptor complexes with incomplete charge transfer [pEPC +$\sigma$⋯V2O5+$\sigma$] and [pdBEPC+$\sigma$⋯V2O5-$\sigma$] is made. The surface morphology of the composites differs in the size of V 2O5 fibers and polymer grains; the polymer inclusions in the composites are of different character. A surface morphology study reveals that the composite constituents - polymer base and V2O5 fibers - are nanosized.
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Papers by Peter Lytvyn
Представлено основні наукові та практичні результати з таких напрямів: математичне та комп’ютерне моделювання, апаратно-програмні засоби автоматизованих систем керування, застосування цифрових технологій в освітньому процесі.
Для науково-педагогічних, наукових і педагогічних працівників, які цікавляться сучасними проблемами застосування математичних методів і цифрових технологій в освіті й науці.
Монографія присвячена актуальній проблемі відновлювальній хірургії. У ній зібрані, впорядковані і проаналізовані усі дані, які були відомі тільки вузьким фахівцям в різних галузях знань, розглядаються патофізіологічні причини виникнення реакції організму на штучні імплантати. Для опису цих процесів використовувалися сучасні фізичні і біохімічні методики. Характеристика поверхні імплантатів скануючим електронним мікроскопом(СЕМ) і, особливо, використання атомно-силового мікроскопу (АСМ) показали, що існує вплив імплантатів на організм реципієнта і його можна виразити у фізичних одиницях - нано Ньютонах. Завдяки цьому пропонується новий алгоритм в доопераційної підготовки пацієнтів. Монографія є зразком роботи, де описані патофізіологічні процеси між чужорідним тілом і тканинами організму на нанорівні з використанням міждисциплінарного підходу до вирішення важливої проблеми.
The monograph is intended for researchers and specialists engaged in semiconductor electronics. It may be of use also to lecturers, post-graduates and undergraduates dealing with the above problems.
relaxation in the ТіВ2–GaAs (InP, GaP, SiC) contacts is considered. An analysis is made of the features of the effect of microwave and 60Со g-radiation on the electrical characteristics of resonant tunneling diodes made on the basis of AlGaAs–GaAs heterojunctions, as well as gallium arsenide tunnel diodes with a d-layer in the space-charge region. The experimental data on the effect of microwave radiation on defect modification in the SiO2–GaAs (SiC) structures are presented. The effects in the nanocrystalline silicon–silicon systems induced by microwave radiation are considered. Much space is given to the effects produced by microwave and 60Со g-irradiation in the Та2О5–Si structures, depending on the conditions of Та2О5 formation.
The monograph is intended for researchers and those engaged in development of microwave devices. It may be of use also to post-graduates and undergraduates specializing in the corresponding areas.