D.M. Freik, V.I. Holota
The Analysis of Wavelets Transforms and Their Applied Application
‘Vasyl Stefanyk’ Precarpathian National University,
Shevchenko str., 57, Ivano-Frankivsk, 76000, Ukraine,
The orthonormalized base of vector spaces, concept of wavelets for continuous and discrete signals is considered. It is shown, that multiresolution analyses allow to express scaling functions and wavelets through sets of factors. Use of digital filters and Z-transforms for subband transformations of signals is considered. Feature of biorthogonal transforms is shown. The review of practical application of wavelet transforms is carried.
B.V. Andriyevskya), W. Ciepluch-Trojaneka),
M.O. Romanyukb), A.A. Patryna), G.M. Romanyukc)
Electron energy structure of DGN crystal from first-principal calculations
a)Faculty of Electronics and Informatics, Technical University of Koszalin,
2, Śniadeckich Str., Koszalin, 75-453, Poland (E-mail:email@example.com) b)The Ivan Franko National University of L’viv,
8, Kyrylo and Mefodii Str., L’viv, 79005, Ukraine
c)Institute of Physical Optics,
23, Dragomanova Str., L’viv, 790005, Ukraine
Ab-initio calculations of band structure, density of electron states, and optical spectra of ferroelectric diglycine nitrate crystal (DGN) are presented for the first time. The investigation presented relates to the optimized structure of DGN. Peculiarities of the calculated band structure characterize DGN as a molecular crystal. Calculated optical spectra agree satisfactorily with corresponding experimental data in the photon energy range 3 – 13 eV.
Keywords: Band structure of crystalline semiconductors and insulators; Optical properties.
I.A. Bolshakova1, V.N. Brudhyi2, D.M. Zayachuk1,
V.T. Maslyuk3, I.H. Megela3, T.A. Moskovets’1, F.M. Shurygin1
Electron Irradiation Influence on InSb<Sn> and InAs<Sn> Microcrystals
1Magnetic Sensor Laboratory, Lviv Polytechnic National Univ.,
1, Kotliarevsky Str, Lviv, 79013, Ukraine, (032)297-03-93, E-mail:firstname.lastname@example.org
2V.D. Kuznetsov Siberial Physical Technical Institute, Tomsk, 634050, Russia
3Institute of Electron Physics of Ukrainian National Academy of Science, Uzhgorod, Ukraine
The investigations were performed on electron irradiation influence on InSb<Sn> and InAs<Sn> microcrystals, grown by chemical transport reactions method (CTR), which are characterized by high structural perfection and low density dislocation. So they have special practical importance for manufacturing magnetic field sensors on their basis to be used under extreme conditions. The investigations were performed on concentration and dose dependences of charge carriers’ relative change under electron irradiation conditions. Also there are given the explanations of these materials behavior peculiarities after them having been irradiated by high-energy particles.
M.V. Karpets, Yu.V. Milman
Diffraction 'in-situ’ study of Al-Cu-Fe-X quasicrystalline powders for thermal-sprayed coatings
Frantsevich Institute for Problems of Materials Science,
3, Krzhizhanovsky Str., Kyiv-142, 03680, Ukraine; E-mail:email@example.com
Structure and phase composition of Al-Cu-Fe-Õ (Õ = Cr, Sc) powders atomized by high-pressure water are investigated. As-atomized powders had two main phase components: a quasicrystalline phase of icosahedral symmetry () and lattice parameter a = 0.63466(7) nm and a cubic phase (), a = 0.29236(3) nm. The relation of phase amounts depended on powder particle size. X-ray in-situ investigation (monochromatic CuK radiation) in He environment of powders while heating revealed the occurrence in them of a complete phase transition at temperatures of 550-600Ñ after 1 h holding. It was accompanied by lowering the -phase lattice period to the value a = 0.63167(2) nm. X-ray diffractometric analysis has shown the existence of the -phase in the given powder sample to a temperature of 870 Ñ. Alloying Al-Cu-Fe powders by Sc and Cr led to changing the relation of amounts of - and -phases as well as of their lattice parameters in as-atomized condition and appearing new phase components at temperatures of 600-800Ñ in process of powder heating. The temperature functional dependence of the -phase lattice period in Al63Cu25Fe12 and Al62,56Cu25Fe12Sc0.44 powders are established.
Keywords: quasicrystalline phase, in-situ X-ray investigation, Al-Cu-Fe system.
G.A. Sukach, P.F. Oleksenko, P.S. Smertenko, A.M. Evstigneev, A.B. Bogoslovskaya,
Charge Injection into Porous Silicon in the Temperature Range from 77 K to 400 K
Institute of Semiconductor Physics of National Academy of Sciences of Ukraine,
45, Nauki Av, Kyiv, 01028, Ukraine
This article describes the charge injection into porous silicon structures fabricated by electrochemical treatment of 20 Ohmcm p-type silicon. The I-V characteristics, photoluminescence spectra and lifetime kinetics have been studied at temperatures 77 K, 293 K and 373 K. Measurements show that the photoluminescence in porous silicon layers results from the recombination of electrons and holes captured in potential wells of various depth and shape; its intensity is controlled by nonradiative recombination on the wire boundaries. The charge flow in the Au(Al)-porSi-Si-Al structure results from the charge transfer in the metal – thin insulator – semiconductor configuration. The current is not restricted by the conductivity of insulating layers; it is restricted by the generation processes in the regions of space charge and semiconductor/ insulator interface due to large amount of defects with various ionization energies. Potential barriers at the surface of porous silicon are formed due to surface defects at the interface silicon wire/oxide; their generation tends to shift the surface potential to the intrinsic value.
Keywords: porous silicon, photoluminescence, surface defects.
I.F. Muronyuk1, B.K. Ostafiychuk1, V.I. Mandzyuk1,
I.I. Grigorchak2, R.Y. Ripetsky3
Kinetic characteristics of Li+ ion intercalation process of silica – carbon nanocomposites
1Vasyl Stefanyk Precarpathion National University,
57, Shevchenko Str., Ivano-Frankivsk, 76000, Ukraine
E-mail:firstname.lastname@example.org, phone: +(03422) 59-60-75
2National University “Lvivska Politechnika”,
Kotlyarevskogo Str., 1, Lviv, 79000, Ukraine
3Kolomyya Institute of Management by Natural Resources,
5, Kotsyubynsky Str., Kolomyya, Ukraine
Kinetics of electrochemical lithium ion introduction process into silica – carbon nanocomposites is researched by impedance spectroscopy method. It is set, that passivation layer is formed on explored material surface at the growth of the “guest” loading degree. The new mechanism of charge accumulation (non-faraday hypercapacity) is found in given materials.
O.I. Bodak1, V.A. Romaka2, Yu.V. Stadnyk1,
L.P. Romaka1, V.F. Chekurin2, Yu.K. Gorelenko1
Impurity band effect on TiCo1-xNixSb conductivity. Donor impuriti
1Ivan Franko Lviv National University,
6, Kyryl & Mephodiy Str., Lviv, 79005, ph. (032)-296-45-03; Å-mail:email@example.com
2Ya. Pidstryhach Institute for Applied Problems of Mechanics and Mathematics Academi of Sciences of Ukraine,
3-b, Naukova Str., Lviv, 79053, Ukraine, ph. (0322)-63-71-11; Å-mail:firstname.lastname@example.org
3L.V. Fock Institute of Physics, St. Petersburg State University,
1, Ulyanovskaya Str., Petrodvorets, St.-Petersburg, 198504, Russia; Å-mail:email@example.com
The role of the impurity donor band in the conductivity of doped and compensated semiconductors with MgAgAs structure type was investigated. A simulation of the electronic structure for TiCo1-xNixSb semiconducting solid solution was carried out. A scheme of the impurity band transformation in TiCoSb semiconductor due to donor impurities doping was advanced. A transition of conductivity from activated to metallic type while TiCo1-xNixSb solid solution composition changes was observed. We relate this transition with Anderson-type transition.
I.S. Novosad, O.M. Bordun
The Electret States in Pb²2 Crystals
‘Ivan Franko’ Lviv National University,
Franko Lviv National University, 1, Universytetska Str., Lviv, 79000, Ukraine, tel. (0322) 964-679, E-mail:firstname.lastname@example.org
In this paper the complex investigation of electret states (ES) of nonactivated iodide lead crystals have been carried out. It is established, that ES are created by cooling and the dark polarization, and by photopolarization by light from region of 515 nm and by light from region of intrinsic absorption at 85 K. The effect of IR-light on the photopolarized crystal at 85 K gives in the considerable decreasing of the photosensitivity in near edge region, but weakly influences on the photosensitivity in the region of intrinsic absorption. Thus the intensive current of a photodepolarization “flash” type which kinetics of a relaxation is featured by two exponential curves have been registered. On the basis of the analysis of the received and literary data the spectral sensitivity of photoelectret states in IR spectral region can be tied with F-type centres.
S.I. Drapak, Z.D. Kovalyuk
Self-organizing of the interface in the p-GaSe-n-InSe heterojunctions prepared by fitting onto optical contact during long-term storage
I.M. Frantsevich Institute of Material Sciences Problems, National Academy of Sciences of the Ukraine,
5 I. Vilde Str., Chernivtsi, 58001, Ukraine tel: 8(+0372) 52-00-50, E-mail:email@example.com
Changers of barrier parameters in photodiodes based onto p-GaSe-n-InSe optical contact in an aging process were investigated. It is determined that the diffusion of oxygen leads to the formation of real close contact between semiconductors during long-term storage. Moreover an aged heterojunctions acquires new properties, which are conditioned by quantum-dimensional effects.
P.Yu. Stakhira, O.I. Aksimentyeva1, V.V. Cherpak
Heterostructures Based on Conducting Polymer Films on the Surface of Inorganic Semiconductors
Lviv Polytechnics National University,
12, Bandera Str., Lviv, 79013, Ukraine tel: (032) 258-26-03, E-mail:firstname.lastname@example.org
1Lviv Ivan Franko National University,
8, Kyryla-Mefodia Str., Lviv, 79005, Ukraine, E-mail:email@example.com
In presented paper carried out optimization of heterostructure properties with a polyaniline layer, as a hole injection layer, on a example of polyaniline-porous silicone heterostructure. The thickness influence of polymer layer, fabricated by cyclic potential shift, on heterostructure characteristics were studied. On the base of carried out work were fabricated and investigated polyaniline-porous silicone heterostructure.
A.A. Druzhinin, I.I. Maryamova, Yu.M. Khoverko, S.M. Matvienko
The Properties of Polysilicon-on-Insulator Layers at Cryogenic Temperatures and High Magnetic Fields
Lviv Polytechnic National University, Sci.-Research Center “Crystal”,
1, Kotlyarevsky Str., Lviv, 79013, tel.(0322)721632, E-mail: firstname.lastname@example.org
The properties of boron doped polysilicon-on-insulator layers, unrecrystallized and after laser recrystallization, were investigated in the temperature range 4.2÷300 Ê and high magnetic fields. The effect of laser recrystallization on the temperature dependence of resistance for polysilicon layers with different carrier concentration at low temperatures was studied. Magnetoresistance of poly-Si layers was measured in magnetic fields up to 14 T at cryogenic temperatures. The possibility to develop temperature sensors and piezoresistive mechanical sensors based on poly-Si on insulator layers operating at cryogenic temperatures and high magnetic fields was shown.
B. Melnichuk, B. Penyukh, Z. Stasyuk
The electrical conductivity and the thermoelectric power of manganese and iron films
‘Ivan Franko’ Lviv National University
50, Dragomanova Str., Lviv, 79005, Ukraine
Under ultrahigh vacuum conditions the influence of the surface and the grain-boundary scattering on the electrical conductivity and the thermoelectric power of thin manganese and iron films were investigated. The experimental results were interpreted in the framework of modified quasiclassical theories of size-effects. It was supposed there were two independent groups of charge carries in transition metal thin film. The surface and the grain-boundary scattering had influence on charge transport of each group separately.
D.M. Freik, B.S. Dzundza
The Surface Influence and Intergrain Boundaries on Charge Mobility on Lead Tellurides Thin Films
Physics and Chemistry of Solid State Department, ‘Vasiliy Stefanyk’ Precarpathian National University,
201, Galytska Str., Ivano-Frankivsk, 76000, Ukraine, E-mail:email@example.com
It is researches the charge carrier mobility due the thickness on PbTe thin inlaid films, growth on mica. The contribution of both the surface and intergrain boundaries is mark.
P.I. Ignatenko1, F.F. Goncharov2, D.N. Terpiy1,
Obtaining both research of structure and composition of films of products solid-phase of reactions
1Donetsk National University, 24, Universitetskaya Str., Donetsk, 83055, Ukraine,
2Donbass State Mechanical Engineering Acadrmy, 72, Schkadinova Str., Kramatorsk, Ukraine
The outcomes of researches of films obtained by different methods of an ionic deposition are reduced. Is exhubited, that phase-formation and structure of bfilms of chemical compounds are defined mainly by velocity deposition of atoms on a substrate.
V.P. Makhniy1, M.F. Pavlyuk1, O.M. Slyotov2
Analysis of Defect Formation Mechanisms in ZnSe:Mg Crystals
1) ’Vasyl Stefanyk’ Precarpathian National University,
201, Galytska Str., Ivano-Frankivsk, 76000, Ukraine, E-mail:firstname.lastname@example.org
2) ‘Yuriy Fedkovych’ Chernivtsi National University,
2, Kotsyubynskiy Str., Chernivtsy, 58012, Ukraine, Å-mail:email@example.com
By method of quasi-chemical reactions the calculation of equilibrium concentration defects in ZnSe crystals doped by isovalence impurity of Mg from vapour phases is lead. It is shown, in the samples of annealing at 1200 K the vacancies of selenium prevail that interlattice selenium, that luminescences accountable for forming of intensive blue bar.
S.S. Lisnyak, G.D. Boyko, M.V. Kedyk
New approaches to computation of speed of reduction of hematite and mechanism of process
‘Vasyl Stefanyk’ Prekarpthian National University,
201, Galytska Str., Ivano-Frankivsk, 76000, Ukraine
It is offered on principle new methods of speed computation of reduction of hematite and mechanism of interactions, which consist in conducting of computation in relation to oxygen which is in an oxide on the given time, that is on unit of reactive oxygen. New conformities to the law of process of reducing are set and they are accounted for according to the method of nonstoichiometrical oxides with a different nature and concentration of defects.
G.V. Korenkova, O.M. Shcherbatiy1, S.A. Nediljko2,
O.Kh. Tadeush3, V.M. Uvarov1
Electronic Structure of the YVO4 Oxygen
‘K.D. Ushynsky’ South-Ukraine State Pedagogical University, 26, Staroportofrankivska Str., Odesa, 65091, E-mail:firstname.lastname@example.org
1’G.V. Kurdyumov’ Institute of the Physics of Metals NAS of Ukraine,
36, Acad. Vernadsky Av., Kyiv, 03680
2’T.G. Shevchenko’ Kyiv National University,
62a, Volodymyrska Str., Kyiv, 01033
3‘K.D. Ushynsky’ South-Ukraine State Pedagogical University, 26, Staroportofrankivska Str., Odesa, 65091
Electronic structure of the YVO4 ortovanadate is investigated using X-ray spectroscopy as well as the band-structure LAPW-calculations. The information about the charge and spins description of atoms, and also about law’s conformities of power zones forming of the valency states in an oxide YVO4 has been receipt.
Ionized and electroneutral defects in CdTe crystals
‘Vasyl Stefanyk’ Preñarpathian National University, 57, Shevchenko Str., Ivano-Frankivsk, 76000, Ukraine, E-mail:email@example.com
The analysis of defects in CdTe crystals annealed in cadmium vapour at temperatures Ò = 973-1273 Ê is carried out. It has been shown that within whole range of cadmium vapour partial pressures the concentration of ionized native point defects is considerably higher than neutral ones. At room temperatures, neutral defects are dominate. Conditions of thermodynamic n-p-transition are determined.
Î.Î. Êîrovyanko1, Yu.P. Gnatenko2, P.M. Fochuk1,
Defect structure peculiarity and properties of CdTe<In> single crystals with various stoichiometric deviation
1Chernivtsi National University, Chemical department,
2, Kotziubinskogo Str., Chernivts, 58012, Ukraine
2Institute of Physics of NAS of Ukraine,
46, Nauki Av., Kyiv, 03028, Ukraine
Influence of stoichiometric relations on the defect structure of CdTe<In> crystals was studied by the photoluminescence (PL) investigation of system-defined annealed samples with various deviation from stoichiometry. The connection of main bands in PL spectrum with In point defect complexes (In+CdV-Cd)- and (2In+CdV-Cd)0 is shown. Neutral complexes dominate in the crystals annealed under cadmium vapour pressure PCd, ionized ones - in the crystals annealed under PTe2. The CdTe<In> point defect structure modeling using the quasi-chemical defect reaction theory was carried out.
Point defects and their compensation in mercury telluride
‘Vasyl Stefanyk’ Prekarpathian University,
201, Galytska Str., Ivano-Frankivsk, 76000, Ukraine
On the basis of crystal-quasi-chemical equalizations for HgTe the expected concentrations of point defects and transmitters of current in the maximum scopes of region of homogeneity. The theoretical calculation of isotherms and isobars of concentration of point defects is conducted V-Hg, Hg+i, Hg+2i and the mechanisms of processes of defect formated are offered in crystals HgTe at annealing in the wide range of change of mercury presser vapour 102-105 Pa at the temperatures of annealing 523, 673 K. Analyses processes of self-compensation of defects.
B.Ò. Boyko, G.S. Khrypunov, À.V. Meriuts, O.P.Chernykh
The Investigation ITO/Cds/CdTe/Cu/Au Thin Film Solar Cells
National Technical University "Kharkov polytechnical institute"
21, Frunze Str., Kharkov, 61000, Ukraine Tel. 380-752-23-57-91 Fax 380-572-587003 , E-mail:firstname.lastname@example.org
By use modeling experimental light current-voltage characteristics of the ITO/CdS/CdTe/Cu/Au thin film solar cells was shown, that after CdCl2 treatment the maximal efficiency is observed at the CdCl2 thickness, which provides the minimal values of series resistance and diode saturation current density simultaneously. The physical mechanisms which determine ITO/CdS/CdTe/Cu/Au thin film solar cells efficiency after CdCl2 treatment are offered.
V.V. Pogosov, E.V. Vasuytin
Zero conductance gap of the single-electron transistor based on the metal cluster
Zaporizzhya National Technical University,
64, Zhukovski Str., Zaporizzhya, 69063, Ukraine tel. (0612) 64-67-33 , E-mail:email@example.com
We have carried out a theoretical investigation of single-electron effects in the structure consisting of two coupled tunnel junctions. A quantization of spectra of the central electrode was taking into account. We discussed an origin of the zero conductance gap, calculated its value and voltage asymmetry.
This work was supported by the Ministry of Education and Science of Ukraine and Samsung Corporation.
Explosive noise of the silicon photodiodes
226, Chervonoarmiyska Str., Chernivtsi, 58013, tel./fax (0372) 57-50-52 , E-mail:firstname.lastname@example.org
The nature of explosive noise at the devices, back displaced the semiconductor, including silicon photodiodes is considered. Is shown, that the presence at silicon photo diodes is connected to increased density dislocation and dot defects in area p-n of transition, concentration of an impurity. One of the basic sources of generation explosive noise is the surface of a crystal of the photo diode.
G.I. Gurina, K.N. Savchenko*
Bentonite-Organic Oligomer Nanocomposites
Technical Uniνersity "Kharkov Polytechnic Institute",
21, Frunze Str., Kharkov UA-61002, Ukraine
*B.I. Verkin Institute for Low Temperature Physics and Engineering, The National Academy of Sciences of Ukraine,
47, Lenin Aνe., Kharkoν UA-61103, Ukraine,
Bentonite-organic oligomer (alkyd, polyurethane, polyetherimide νanishes) nanocomposites synthesized by the intercalation method are proposed for using in composition of paintwork materials. The results of physicomechanical and physicochemical studies of the nanocomposites and the coatings on their base are presented and analysed. An increasing in the νalues of hardness and endurance of the coatings with nanocomposites are determined.
H.A. Sirenko1, L.Ya. Midak1, V.P. Sviderskyy2,
O.S. Drobot2, L.V. Karavanovych1
The influence of neighboring surfaces on antifriction properties of composite polymer materials. Orientation carbon-plastics
1Vasyl Stefanyk’ Precarpathian National University,
57, Shevchenko Str., Ivano-Frankivsk, 76000, Ukraine
2Khmelnitsky National University
11, Institutska Str., Khmelnitsky, 29000,Ukraine
The dependence of antifriction properties of polymer composites filled by carbon fiber materials from mechanical and thermal-physics properties of neighboring surfaces of solid state has been researched. It has been ascertained, that orientation of layers of filler of composite material about vector of speed realizes the main influence on wear of neighboring surface. It has been ascertained, antifriction properties don’t depend from hardness of neighboring surface, but are determined by state of starting surface of counterbody and surface layers, which are formed on surfaces of composite and neighboring surface in friction for orientation composite materials.
E.V. Lyapina, A.I. Kostrzhytskiy
To a Problem on Moisture Resistance of Condensed of the Systems Cuprum-Tin and Their Clones
Odessa National Academy of Food Technologies,
112,Kanatna Str., Odessa, 65039,Ukraine, E-mail:profAIK@ipss.net
The results of research of the stability of moisture condensed tapes of alloys are resulted on the basis of copper in a moist atmosphere. In grain changes of contact resistance the most proof and most stable systems of Cu-Sn, Cu-Sn-Ni and Cu-Sn-Al are certain. With the use of method of grade correlation the comparative analysis of the condensed systems is conducted and optimum composition is chosen on the parameter of “stability of moisture”.
O.I. Aksimentyeva, N.I. Domatsevich*
Permeability of the polymeric modified materials
‘Ivan Franko’ Lviv National University,
10, Kyrylo and Mefodia Str., Lviv-5, 79005, Ukraine,,
*Lviv Commercial Academy,
10, Tugan-Baranivskogo Str., Lviv, 79008, Ukraine, E-mail:standar@ lac.lviv.ua
The change of the diffusion characteristics of the polymeric modified materials intend for anticorrosive protection of metal surfaces is investigated. The influence of inhibitors and plasticizers on passage and change of barrier properties of materials during age hardening is determined.