Applied Physics Researches Division (APRD)

Posts made in April, 2018

New publication in peer-reviewed journal

Posted by on Apr 20, 2018

Our new paper has been published in “The Journal of Electronic Materials” monthly peer-reviewed scientific journal (Impact factor: 1.579 (2016))  and is available for downloading: The Use of Different Pulsed Electron Irradiation for Formatiion of Radiation Defects in Silicon Crystals   Abstract This paper reports the formation of structural defects in the lattice of silicon (n-Si) single crystals, as a result of irradiation by different intensities and pulses of electrons. The samples were studied by means of Hall effect measurements of electro-physical parameters (specifically the concentration of the main charge carriers) as a function of temperature and radiation dose. The role of the radiation current density (pulse height) is discussed, which gives rise to a peculiar behavior in the electrical-physical properties of n-Si. In particular, thermal processes are found not to develop, due to the ultrafast (pulse duration in the range 10−12–10−13s) nature of the incident radiation, which causes an almost “pure” energy interaction to occur between the radiation and the atoms within the crystal, and the formation of cluster defects. A scheme for the time-scale of the formation of these radiation defects is presented. From the dose and temperature dependences of the concentration of main charge carriers, the radiation defects introduction rates were determined.       Quasi-Chemical Reactions in Irradiated Silicon Crystals with Regard to Ultrafast Irradiation   Abstract This paper reports results from an investigation of the interaction of displaced Si-self atoms (I) and their vacancies (V), with impurities in crystalline silicon (Si), as induced by micro-second pulse duration irradiation with electrons at different energies: 3.5, 14, 25 and 50 MeV and pico-second pulse duration with energy 3.5 MeV. V-V, I-impurity atom and V-impurity atom interactions are analyzed both experimentally and as modeled using computer simulations. A process of divacancy (V2) accumulation in the dose-dependent linear region is investigated. The effect of impurities on recombination of correlated divacancies, and I-atoms that had become displaced from regular lattice points is estimated by computer modeling of an appropriate diffusion-controlled process. It is concluded that the experimental results can be interpreted quantitatively in terms of a strongly anisotropic quasi-one-dimensional diffusion of displaced I-atoms. In addition, a significant difference is found between the effects of pico-second duration electron beam irradiation, which causes the formation of A-centre (V + Oxygen) clusters, while when the beam is applied on a micro-second timescale, divacancies are created instead, although the electrons have the same energy in both...

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Setting for measuring of the lifetime minority charge carriers of semiconductors

Posted by on Apr 13, 2018

Setting for measuring of the lifetime  minority charge carriers of semiconductors

The lifetime of the minority charge carriers of semiconductors is determined by the method of measuring the decay time constant of the signal of the recombination process of nonequilibrium charge carriers in a semiconductor. Nonequilibrium charge carriers are generated by illumination of a sample with a radiation length of 1.05 μm (for Si), the decay process is detected by microwave absorption at a frequency of 12 GHz and recorded on an oscilloscope. The accuracy of the measurement is ± 10%, the msmeasurement time interval is is from 1μs to 10 μs, the sample size is 10x4x1 mm-3. This is the only method of completely non-destructive non-contact measurement of the lifetime of minority charge carriers of semiconductors. [nggallery id=5...

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Project: ISTC A-2133p (2015-2017)

Posted by on Apr 5, 2018

Annual Technical Report A-2133, 2016 Final Technical report...

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Project: ISTC A-1605

Posted by on Apr 5, 2018

Project: ISTC  A-1605

Development of High-Efficient Filter Systems on the Basis of Super-Thin Basalt Fiber for Radioactive Aerosols Purification and Creation of a Work Circle for Filters Manufacturing with the Purpose of Their Operation at Nuclear Power Plants  ( ISTC  A-1605) At present, creation of highly effective energy- and resource- saving low-waste and safe technologies for cleaning of environment from radioactive emissions of nuclear-powered industrial enterprises, nuclear power plants and thermonuclear facilities presents undoubtedly an actual problem. Number of participants: 27 Number of publications related to the Project: 10 Number of conferences: 8 (Germany, Moscow, Kiev, Almaaty, Sevastopol, Sochi. Patent: АМ 20110016 The Project implementation has allowed creating of highly efficient filtering system for cleaning radioactive aerosols at nuclear power plants. For this purpose: A new method for obtaining of modified sorbents on the basis of super-thin basalt fiber with significantly enhanced sorption characteristics was offered. A pilot lot of new filters for cleaning of ventilation air from finely dispersed radioactive emissions was manufactured and installed in V2 ventilating system of the Armenian nuclear power plant. Their cleaning efficiency makes 98.4 to 99.6 %, which is comparable to efficiency of the IAEA standards for regular filtering blocks. A technological process of manufacturing filters from super-thin basalt fibers was developed. A technology of regeneration for the used filters after their withdrawal from service was developed.   The offered filters, manufacture of which is based on local raw materials, are economic and two times cheaper than others used till now at the Armenian NPP. It is intended to use, starting from the next 2014 year, the developed modified super-thin basalt fibers for air cleaning from radioactive isotopes in normal operation regime of Armenian NPP.   Success Story At present, one of global environmental problems is creation of highly effective enterprises and devices for processing, recycling and burial places for wastes, life-support equipment. All of them demand new hybrid technologies, which, in turn, demand creation of new functional and constructional materials with rather specific properties. Therefore creation of highly effective energy- and resource-saving low-waste and safe technologies for cleaning of environment from radioactive emissions of nuclear-powered industrial enterprises, nuclear power plants and thermonuclear facilities presents undoubtedly an actual problem. Under the financial auspices of the International scientific and technical centre, significant contribution is made in solution of this problem.             Research of highly effective filtering systems of protection of the population and environment from radioactive emissions from the Armenian nuclear power plant, conducted in A.I. Alikhanian National scientific laboratory (former Yerevan Physical Institute) and in the Research Center For The Problem Of The Non Proliferation Of Mass Destruction Weapons, was supported within the framework of ISTC A-1605 Project financed by Canada. The Project activities were begun in January 2009 in close cooperation with foreign collaborators from AMEC NSS Limited, 700 University Avenue, Toronto, Ontario, Canada. The Project collaborators were recognized leaders in the field of filtering systems, and their participation guaranteed continuity of methodology and technical approach to the Project tasks.             Super-thin basalt fibers...

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