SUMMARY
GALLIUM ARSENIDE TECHNOLOGY POSSIBILITIES FOR RADIATION DETECTION
Khvedelidze L.V., Khuchua N.P., Kobrava N.G., Lezhneva T.M., Melkadze R.G.,
Natsvlishvili L.G., Peradze G.G., Sakharova T.B., Sanikidze L.P.,
Berthold A. and Besse I.
RPC Electron Technology, Tbilisi State University
Fraunhofer Institute for Nondestructive Testing, Dresden, Germany
For the last decade, semiconductor microsystems for radiation detection have found increasing application in the fields of medical imaging, structural biology, space investigaiton, non-destructive testing, detection of charged particles, and dosimetry. In this paper, the advantages of the use of gallium arsenide as directly converting material in radiation detectors are described, the sensor parameters the criteria of selection of the converting material, and the device designs for various purposes are given. Some results of the joint development of X-ray sensors for non-destructive testing are presented. The possibilities for application of the developed technology in fabrication of strip detectors and pixel matrices for medical imaging and dosimetry are considered.
Keywords: radiation detectors, gallium arsenide technology, X-ray sensor
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PROPERTIES OF BORON CARBIDE FILMS PREPARED BY A LASER PLASMA DEPOSITION METHOD
Shalamberidze S.O., Kervalishvili P.J. and Mikelashvili V.T.
Georgian Technical University
High Technology Center of Georgia
Boron carbide thin films have been produced by a method of laser plasma deposition. Depending on the experimental conditions, amorphous, polycrystalline and oriented films have been produced. The investigations of the composition and energy characteristics of the laser plasma have been carried out. The experiments showed that the plasma formed during boron carbide film production by a method of laser plasma deposition contained up to 20% of ions with the mean energy of 120 eV. A considerable decrease in the temperature of crystalline growth was observed in the films deposited on the NaCl substrate from a target of boron carbide enriched with the 10B isotope up to 90 %.
Keywords: boron carbide films, laser plasma deposition, boron isotope.
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FABRICATION OF NANOPARTICLES AND NANO-SIZED FILM ELEMENTS
Khoperia T. N., Zedginidze T.I., Maisuradze L.G., Khoperia N.T. and Chikhradze V. S.
E. Andronikashvili Institute of Physics, Georgian Academy of Sciences
The aim of the work was fabrication of nanosized film elements and powder-like materials. Another aim of the work was replacement of gold and silver with non-precious metals. The mechanism of sensitization and activation of nonmetallic materials was established. The process of electroless metallization is considered. The ductility tester of a new design is proposed. The production processes of electroless metallization were developed and implemented in microelectronics, space industry, piezoengineering and other fields of production.
Keywords: nanotechnology, electroless metallization, fuel cells, piezodevices.
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PREPARATION, ALLOYING, AND OPTICAL AND PHOTOELECTRICAL PROPERTIES OF THIN FILMS OF NEODYMIUM SESQUISULPHIDE
Jabua Z.U., Davitadze K.D., Dadiani T.O., Gigineishvili A.V. and Stamateli M.I.
Georgian Technical University
The technology for preparation of thin metallic films of g-Nd2S3 by discrete vacuum thermal evaporation of presynthesized bulk metal was developed. Alloying of the prepared thin films with Cd and Pb was carried out. In the photon energy interval from 0.2 to 3.0 eV, at the temperature of 300 K, reflection and transparency spectra were measured. The frequency analysis of the absorption coefficient revealed that g-Nd2S3 corresponds to the exponential edge of absorption. In Cd - and Pb- alloyed g-Nd2S3 films, spectral and temperature dependences of photoconductivity were studied. The measurements were carried out in the range of photon energy of 0.2-3.0 eV and temperature of 115-380 K. Interpretation of the results was based on the assumption about the leading role of acceptor levels formed by vacancies in the cation sublattice at their compensation with the introduced n-type dopants (Cd and Pb) in photosensitivity. The ionization energy of the n-type dopant (Pb) was determined.
Keywords: neodymium sesquisulphide, thin films, alloying, vacuum thermal evaporation, reflection spectra, transparency spectra, absorption coefficient, photoconductivity.
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PREPARATION OF THIN FILMS OF PRASEODYMIUM MONOANTIMONIDE AND THEIR ELECTRO-PHYSICAL PROPERTIES
Jabua Z.U., Dadiani T.O., Gigineishvili A.V., Stamateli M.I. and Lochoshvili T.S.
Georgian Technical University
The technology for preparation of thin films of prasediymium monoantimonide was developed. The samples were prepared by vacuum thermal evaporation from two independent sources of Pr and Sb. The determined lattice constant was a=6.35 A.
For the samples, the temperature dependence of the specific resistivity, Hall constant and emf coefficient in the temperature interval from 100 to 700 K were meansured. On the basis of the measurements, in the one-band approximation, there were assessed the basic parameters of the carriers: mobility and concentration.
Basing on the character of the temperature dependence, electro-physical parameters and their absolute values, it was assumed that PrSb is a semi-metal.
Keywords: thin films, praseodymium monoantimonide, vacuum thermal evaporation, specific electrical resistivity, Hall constant, thermal emf.
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EFFECT OF RADIATION TEMPERATURE ON RADIATION RESISTANCE OF n-Si CRYSRALS
Pagava T.A., Maisuradze N.I., Khasia N.I., Eristavi B.G. and Kharashvili O.G.
Georgian Technical University
There is demonstrated that the efficiency of introduction of radiation defects with high thermal stability (Tann?400?C) of n-type silicon crystals reaches maximum at Tirr=150?C. The observed effect can be explained by formation of mut-vacancy phosphorus-containing defects (PV2 or PV3) on the basis of thermally ionized E -centers and non-equilibrium negative monovacancies.
Keywords: n-Si crystals, radiation resistance, radiation temperature.
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CALCULATION OF SHALLOW AND DEEP IMPURITY LEVELS IN SEMICONDUCTORS OF TETRAHEDRAL SYMMETRY BY USING THE UNIFIED MODEL
Gogua Z.G., Gogua G.Z., Iluridze G.N., Minashvili T.A. and Rtveliashvili G.V.
Iv. Javakhishvili Tbilisi State University
Georgian Technical University
The unified model of the impurity center in semiconductors of tetrahedral symmetry is offered. Basing on this model, by means of the unified approximation, the energies of basic state of shallow and deep impurities of a wide class were calculated. The analytical equation of energetic levels of shallow and deep impurities was derived. The results obtained using this formula are in good agreement with the relevant experimental data.
Keywords: semiconductor, tetrahedora, symmentry, impurities, impurity center, unified model.
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ELECTRON SCATTERING ON IONIZED IMPURITIES IN THE UNIFIED MODEL OF THE IMPURITY CENTER
Gogua Z.G, Gogua G.Z., Iluridze G.N., Minashvili T.A. and Rtveliashvili G.V.
Iv. Javakhishvili Tbilisi State University
Georgian Technical University
The problem of electron scattering on ionized impurities on the basis of the unified model of the impurity center. Within rather wide intervals of temperature and concentration of scattering centers, the known Brooks-Herring law of the temperature dependence of electron mobility m(T)~T3/2 is replaced by dependence m(T)~T1/2. The latter is in better agreement with the relevant experimental data for Ge and Si. Similarly, the theoretical results obtained using this dependence are in better accord with the experimental data on thermal emf than the corresponding Brooks-Herring dependence.
Keywords: electron scattering, ionized impurities, unified model, impurity center.
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NONEQUILIBRIUM GREEN FUNCTION APPROACH TO THE THEORY OF NONLINEAR QUANTUM TRANSPORT PHENOMENA IN ELECTRON-PHONON SYSTEMS
Kotiya B. A.
Georgian Technical University
There were used new exact generalized quantum evolutionary equations for double-time nonequilibrium correlation and Green (retarded, advanced and spectral) functions for study of nonlinear quantum transport phenomena in the electron-phonon system.
The electrons scattering on nonpolar optical phonons in strong external homogenous electric field was investigated with the help of developed Airy formalism. There were considered quantum effects: collisional broadening and an intracollisional field effect. In the case of weak electron-phonon interaction, in the first Bohrn approximation, Dyson's equation for one-particle retarded Green function was solved, a model of the spectral density function was constructed, a double-peak structure of spectral density was obtained, the electron self-energy (mass operator) was calculated, and the equation for quantum-mechanical distribution function which foresees these effects was derived. It was established that the electron self-energy (its real and imaginative part) and particle density sustain damped oscillation, which points to the existence of preferred quantized energetical levels for electrons in a strong external electric field. It was demonstrated that the influence of the strong external electric field alongside with phonons causes such electron movement which can be considered as particle ,,hopping" transport among the discrete states of Airy function, and that the electron trajectory is discontinuous along the field action direction in real space.
Keywords: quantum transport phenomena, correlation functions. theory, Green functions, quantum-mechanical distribution function, self-energy, spectral density function.
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METHOD OF MEASUREMENT OF STATIC AND PULSE PRESSURES BY APPLICATION OF CONDUCTING RUBBERS
Aneli J.N., Kotkhonjia V.P. and Bolotashvili M.M.
R. Dvali Institute of Machine Mechanics, Georgian Academy of Sciences
E. Andronikashvili Institute of Physics, Georgian Academy of Sciences
The method of measurement of static and pulse pressures with application of conducting rubber (CR) is proposed. The method is grounded on the phenomena of changes in the specific volume electrical resistance at the external pressure effect. The change in the CR conductance at rubber compression is proportional to the external pressure effect and is indicated by a bridge circuit. The proposed method allows estimation of the degree of homogeneity of distribution of the pressure force along the surface of the solid material if it is covered with transducers on the basis of CR.
Keywords: conducting rubbers, static pressure, pulse pressure, measurement method.
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SURFACE-BARRIER SEMICONDUCTOR SENSOR BASED ON THE GaP SCHOTTKY CONTACT
Laperashvili T.A., Laperashvili D.L., and Imerlishvili I.I.
Institute of Cybernetics, Georgian Academy of Sciences
Georgian Technical University
Iv.Javakhishvili Tbilisi State University
In this work we describe the technology of fabrication of Surface-Barrier Devices by electrochemical and chemical deposition of different metals on semiconductors A3B5. There was investigated the influence of heat treatment on electrical and photoelectric characteristics of the Au/GaP and In/GaP surface-barrier devices (SBD). The Au/GaP SBD is a device for preparation of sensor of ultraviolet radiation, and In/GaP SBD is sensitive for detection of semiconductor structural defects. Here are presented the results of investigation of Au/GaP and In/GaP Surface-Barrier Devices (SBD) with broken line current-voltage characteristics in a semilog plot. The intervalley energy gap (?E) of conduction band of GaP from current - voltage (I-V) and capacitance-voltage (C-V) characteristics on Au/GaP and In/GaP was determined and ?E = 0.50-0. 51 eV was obtained for [111] oriented n-type GaP.
Keywords: Shottky diode, intervalley energy gap, electrochemical deposition.
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INVESTIGATION OF INTERACTION OF THE THIN GOLD FILM WITH MERCURY AT DEVELOPMENT OF THE MERCURY VAPOR SENSOR
Khachidze N.I., Khachidze T.I., Guliashvili T.A. and Mkheidze T.D
Georgian Technical University
Scientific-Engineering Center of Microelectronics
With the aim of optimization of the parameters of the mercury vapor sensor designed by the authors, the investigation of the mechanism of interaction of mercury with the sensitive element made of a thin gold film was carried out. The investigation results allow drawing the conclusion that optimum measurement time of the sensor is 20-25s. the measurements are desirable to be carried out at low temperatures (40-50iN); the minimum temperature necessary for restoration of the sensitive element is 400iN.
Keywords mercury vapor, absorption, thin film, gold structure.
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MICROELECTRONIC SENSOR OF WIND FLOW DIRECTION AND VELOCITY
Khachidze T.I., Khachidze N.I., Guliashvili T.A., Mkheidze T.D. and Mikuchadze G.A.
Georgian Technical University
Scientific-Engineering Center of Microelectronics
Some problems of designed the sensor of wind flow direction and velocity are considered. A new design of the sensor, in which a monolithic matrix with four planar metal-polymer thermoresistors is used as a sensing element, is described. The results of investigation of metrological characteristics of the sensor are presented.
Keywords: microelectronic sensor, wind direction, wind velocity, metal-polymer thermoresistors.
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ABOUT APPLICABILITY OF THE BASIC ADAPTIVE IDENTIFICATION ALGORITHM IN HIGH-PRECISION ESTIMATIONS OF UNKNOWN PARAMETERS
Odisharia G.B. and Kochoradze G.I.
Avtomatmretsvi Institute, Rustavi
Iv. Javakhishili Tbilisi State University
In connection with urgent need of new approaches to adaptive control and identification in micro- and nanosystems in present article it is investigated properties of family of adaptive algorithms of the identification, generated from so-called basic algorithm. Our interest in it is based on specific of micro- and nanotechnologic objects, which includes in first that at such small dimensions classical properties of a matter and the equation of mathematical physics are difficultly used, and in the second subjects, that for their successful functioning it is necessary to provide high precision in estimations of necessary unknown parameters. Therefore in given article the attention on precise characteristics of above named algorithms concentrates.
Keywords: adaptive algorithm, identification, high-percision estimation, unknown parameters, micro-and nanosystems
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COMPLEX MONITORING SYSTEM
Badrishvili G.N. and Natriashvili T.M.
R. Dvali Institute of Machine Mechanics, Georgian Academy of Sciences
To decrease atmospheric air pollution, complex monitoring a system and measures improving environmental safety of motor vehicles including usage of on-road signs informing population on the atmospheric quality, specific fuel consumption sensors, exhaust gas parameter indicators, and test stations for independent checking, as well as motor vehicles adaptation to ambient conditions, are discussed in this paper.
Keywords: monitoring, environment protection, vehicles, air pollution
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MEASURING SYSTEM FOR CONTROLING ECOLOGICAL INDEXES OF INTERNAL COMBUSTION ENGINES
Natriashvili T.M. and Kenkishvili R.A.
R. Dvali Institute of Machine Mechanics, Georgian Academy of Sciences
For the purpose of control of uniformity of operation of separate cylinders of internal combustion engines (ICE) and minimalization of the exhaust of toxic substances into the atmosphere, there is offered the transducer and measuring complex for registration of pressure in fast thermodynamic processes developed at the Institute of Machine Mechanics of Georgian Academy of Sciences. The design of the transducer excludes the effect of high temperature on the measuring process and allows receiving the signal in an analog form as well as discrete pressure values at the given moment of time.
Keywords: internal combustion engine, operation of cylinders, ecological indexes, measuring system, pressure.
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POWER PLANT MONITORING OF INTEGRITY OF CIRCULATION LOOPS AND MAIN PIPELINES
Kashia V. G., Kadaria M. A. and Zhvania I.A.
I. Vekua Sukhumi Institute of Physics and Technology
The methods for working body leakage control in circulation loops of various- purpose power plants and organic energy-carrier main pipelines are considered. There are presented theoretical and experimental research results. They show that today, from constructional and technological points of view, the universal method of the metallic system hermetic state control is the best developed. This method suggests monitoring of the changes in the permitivity of the control surface nearby areas by time.
It is showed that the universal method of hermetic state control of power plant circulation loops is of great importance for designing of remote control systems for monitoring leakage in gas and oil pipelines. There is given the block diagram of the remote control computer system for registration of energy-carrier leakage moment in gas and oil pipelines.
Keywords: monitoring, power plant, pipeline, integrity, sensor, dielectric, semiconductor, electric capacity, alkali metals, active sorbent, pseudocondenser.
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APPLICATION OF OPTOELECTRONIC SENSORS IN THE GEOPHYSICAL MEASURING SYSTEM
Gugushvili A.Sh., Kervalishvili M.P., Ediberidze A.G., Sesadze V.K. and Kucia I.S.
Georgian Technical University
The problems of earthquake prediction are considered. For earthquake prediction, various methods, including pattern recognition and Gutenberg-Richter's law, were used. An optoelectronic sensor for detection of seismic signals was designed. The software for processing the signals received from such sensors is suggested.
Keywords: optoelectronic sensors, seismic signals, software.
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SEISMIC COMPUTER SYSTEM FOR APPLICATION IN GEOLOGY AND GEOPHYSICS
Kucia I.S.
Georgian Technical University
The seismic sensor we offer, by its operation, sharply differs from the standard seismic sensors. In this sensor, for seismic signal reception and processing is used the optoelectronic device (with application of a semiconductive laser). The sensor consists of a spherical glass vessel which is half-filled with liquid (a viscous one is desirable). On the sensor, are mounted two lasers for reception of wave movements in different directions, and photodetectors. The wave signals reflected from the liquid surface are led to the photodetectors and, finally, through the analog-digital decoder, to the computer input. The use of the optical methods for such processes allow determination of different properties of seismic disturbances with high precision, which can not be discovered by the traditional seismograph. The processes that proceed in the seismograph are described by the Korteveg-de Vries equation.
Keywords: seismic sensor, computer, soliton waves.
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PORTABLE EQUIPMENT FOR CONTROLLING ENVIROMENT
Norakia B.F., Chikovani R.I., Genebashvili Z.I., Minashvili T.A., Mkheidze D.T. and Janelidze A.G.
Georgian Technical University
Scientific-Engineering Center of Microelectronics
Portable devices for environment monitoring were designed. The ratemeterdosemter of ultraviolet radiation was designed on the base of the optoelectronic sensor having a narrow UV spectral range. There was also designed a device for controlling the explosive gas concentration in air and an indicator for monitoring the allowable concentration of carbon monoxide in closed areas.
Keywords: environment monitoring, portable devices, UV radiation, dose, explosive gas, carbon monoxide.
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TECHNOLOGICAL ISSUES OF POWER INSTALLATION INFLUENCE
ON ENVIRONMENT STABILITY
Utiamyshev I. R., Kutovoy G.P. and Simonov V.M.
International Russian-American Institute of Natural
Monopolies Regulation and Energy Conservation, Moscow, Russia
Growing extensive consumption of power and an inevitable coming energy crisis, as well as global pollution of the environment, have created a problem of searching for clean power sources, a new sight on traditional fuel, and progressive technologies of natural fuel processing as a compromise between environmental problems and power source deficiency. New alternative power sources and water purification technologies are discussed as examples.
Keywords: power installations, environment protection, alternative power sources, water purification.
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HYDRODYNAMIC AND MICROTEMPERATURE MONITORING IN SEISMIC AREAS
Buntebarth G., Chelidze T. L. and Melikadze G. I.
Geophysikalisch-Technisches Buro, Clausthal-Zellerfeld, Germany
Institute of Geophysics, Georgian Academy of Sciences
Seismohydrogeodeformation Researches Centre of Ministry of Environment
Protection and Natural Resources
In 1999-2002, investigations were carried out by the authors in the Tbilisi Hydrothermal Field in Eastern Georgia in order to design a hydrodynamic model of the abovementioned region, to study relations between the hydrosphere regime and the tectonic motion, and to define short-term hydrodynamic and microtemperature precursors of earthquakes. In order to achieve these objectives, innovative equipment was tested and improved.As a result, the 3-D numerical model for the Tbilisi Hydrothermal Reservoir was implemented using calibration by temperature and pressure field data. Considerable data on the impact of seismic/tectonic, man-made, meteorological and tidal factors were collected. Clear hydraulic precursors of several local earthquakes of magnitudes 2-3 were recorded. It turned out that, as a rule, the water level rose in several days before the earthquake. The amplitude of tidal variations in water levels also changed during this period. The after-effects of earthquakes were also clearly recorded.
Keywords: seismic area, hydrothermal field, precursors of earthquake, three-dimensional numerical model, water level, microtemperature.
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DEVELOPMENT OF THE METHOD FOR IDENTIFICATION OF EXPLOSIONS IN TUNNELS
Mataradze E.D., Chagelishvili E.Sh., Michelson R.V., Krauthammer T. and Butskhrikidze G.D.
Mining Institute, Georgian Academy of Sciences
Penn State University, USA
Georgian Technical University
The article addresses the development of an automatic system of equipment for the protection from unauthorized explosions, the basic element of which is the module of blast identification. A method of recording and analysis of seismic signals generated in underground structures by different sources has been developed. "Blast-non-blast" signals are identified according to gain and time characteristics of vibration of an artificial wave conductor with strictly homogeneous characteristics. The proposed method ensures increased reliability and higher speed of identification at the expense of the absence of the influence of nonuniform geological structures, fissuring, anisotropy and an absorbing medium.
The obtained data were used for constructing the algorithm and program for the analysis of digital records of seismic signals and blast identification. The program application has confirmed that it ensures reliable identification of the blast in 6-8 ms from the moment of initiation of the charge of the explosive. The experiments were conducted in the underground blasting chamber of the Mining Institute of the Georgian Academy of Sciences. The task was implemented with the financial support of the CRDF (US Civilian Research and Development Foundation).
Keywords: explosions, tunnels, identification, automatic system, safety.
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PROSPECTS OF THE USE OF MAGNETOTAXIS BACTERIA FOR MAKING NANOMATERIALS
Dadunashvili S. A.
Georgian Technical University
The possibility of application of nanomaterial - magnetite, produced from magnetosomas of magnetataxis bacteria, for vectoring the movement of various nanodevices at external magnetic factors is demonstrated.
Keywords: nanomaterials, magnetotaxis bacteria, vectoring of movement, nanodevices.
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PROSPECTS OF APPLICATION GROWTH OF PHOTOELECTRIC SEMICONDUCTOR CONVERTERS OF SOLAR ENERGY IN GEORGIA
Chikovani R.I.
Georgian Technical University
The prospects of development of production and application of photoelectric semiconductor converters of solar energy in Georgia are considered. The program of development of this field of science and technology for 10-12 years is suggested. It is noted that Georgian scientists design the photoelectric converters of solar energy not only on the base of silicon, but also on the base of such semiconductor compounds as GaAlAs. A brief review of the state of the art in foreign countries is given.
Keywords: photoelectric semiconductor converters, solar energy, production development, applicatio.
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OPEN MINING AS A FACTOR OF ACCUMULACION OF TOXIC HEAVY
METALS IN NATURAL WATERS AND ALTERNATIVE METHODS OF THEIR PURIFICATION
Zviadadze U.I., Svanidze Z.S. and Mardashova M.L.
Georgian Technical University
Development of mineral deposits through open mining has heavy consequences in terms of causing drastic deterioration of ecogeochemical state of the environment, namely pollution of the hydrographic net, ground waters and soils with various toxic metals. A large copper-pyrite deposit of Madneuli (South Georgia) has been exploited for years by the open quarry method, ignoring the environment protection measures. Therefore, the ecological situation within the studied region is highly dramatic, and, due to that, the threat of destruction is essentially relating the fauna and flora of the Madneuli Region. Revealing of the laws governing this phenomenon and elaboration of recommendations for the improvement of grave ecological conditions in this very important region of Georgia is the main purpose of the present work.
Keywords: ground waters, river waters, open mining, toxic heavy metals, atomic absorption spectroscopy, environment protection
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EVALUATION AND PREDICTION OF THE POLLUTION DEGREE OF THE SURFACE WATER SOURCES IN THE UNITED STATE MONITORING SYSTEM
Klimiashvili L.D. and Tsikhelashvili Z.I.
Georgian Technical University
On the basis of system analysis, uniform methodological problem of the component monitoring of pollution of surface water sources have been solved.
Basic descriptive models of the qualitative estimation and forecast of the pollution of surface water sources were developed and introduced as the possibility of classification of the ecological state of any water object in accordance with its assigning to undesirable zones: relatively satisfactory situation- ]0.63-1]; emergency ecological situation - d?[0.2-0.37]; ecological disaster - d?]0.2-0.37[ The proposed approach can also be used for development of the monitoring systems for the atmospheric air and soils within the system of the united complex state monitoring.
Keyword: water sources, pollution, state monitoring system, descriptive models, estimation, forecast.
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