Russian Armenian Slavic University

Yerevan, Armenia

Russian Armenian Slavic University

Yerevan, Armenia
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Hayrapetyan D.B.,Russian Armenian Slavic University | Hayrapetyan D.B.,State Engineering University of Armenia | Kazaryan E.M.,Russian Armenian Slavic University | Tevosyan H.Kh.,Russian Armenian Slavic University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

In this paper the electronic states and direct interband light absorption in the spherical quantum dot with modified Pöschl-Teller potential made of GaAs under influence of hydrostatic pressure and temperature effects are studied. For the regime of strong size quantization analytical expressions for the particle energy spectrum and dependencies of effective threshold frequencies of absorption on the geometrical sizes of quantum dot are obtained. The selection rules corresponding to different transitions between quantum levels are found. It has been demonstrated that the reduction of the half-width potential well leads to the blue shift of threshold frequencies, and the reduction of the depth of potential well leads to the red shift of threshold frequency. Selection rules for quantum transitions have been obtained. It has been demonstrated that the reduction of the half-width potential well leads to the blue shift of threshold frequencies, and the reduction of the depth of potential well leads to the red shift of threshold frequency. Selection rules for quantum transitions have been obtained. Kewwords: Spherical qunatum dot, hydrostatic pressure, modified Pöschl-Teller potential, absorption coefficent, direct interband light absorption. © 2013 SPIE.


Hayrapetyan D.B.,Russian Armenian Slavic University | Hayrapetyan D.B.,State Engineering University of Armenia | Hovhannisyan L.T.,State Engineering University of Armenia | Mantashyan P.A.,Armenian National Academy of Sciences
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The analysis of complex spectra is an actual problem for modern science. The work is devoted to the creation of a software package, which analyzes spectrum in the different formats, possesses by dynamic knowledge database and self-study mechanism, performs automated analysis of the spectra compound based on knowledge database by application of certain algorithms. In the software package as searching systems, hyper-spherical random search algorithms, gradient algorithms and genetic searching algorithms were used. The analysis of Raman and IR spectrum of diamond-like carbon (DLC) samples were performed by elaborated program. After processing the data, the program immediately displays all the calculated parameters of DLC. © 2013 SPIE.


Hayrapetyan D.B.,Russian Armenian Slavic University | Hayrapetyan D.B.,State Engineering University of Armenia | Dvoyan K.G.,Russian Armenian Slavic University
Journal of Physics: Conference Series | Year: 2012

Within the framework of adiabatic approximation the energy levels and direct interband absorption of light in a strongly oblate truncated ellipsoidal quantum dot's ensemble are studied. Analytical expressions for the particle energy spectrum and absorption threshold frequencies in the regime of strong size quantization are obtained. Selection rules for quantum transitions are revealed. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the minor semiaxe by two experimentally realizing distribution functions have been taken into account. Distribution functions of Lifshits-Slezov and Gaussian have been considered.


Hayrapetyan D.B.,Russian Armenian Slavic University | Hayrapetyan D.B.,State Engineering University of Armenia | Kazaryan E.M.,Russian Armenian Slavic University | Kotanjyan T.V.,Russian Armenian Slavic University | Tevosyan H.K.,Russian Armenian Slavic University
Superlattices and Microstructures | Year: 2014

In this paper the exciton and electron sates in cylindrical quantum dot with Morse potential made of GaAs are studied. For the regime of strong size quantization, energy spectrum with the parabolic approximation case are compared. For strong and weak size quantization regimes analytic expressions for the particle energy spectrum, absorption coefficient and dependencies of effective threshold frequencies of absorption on the geometrical parameters quantum dot are obtained. For the intermediate size quantization regime the problem solved in the framework of variation method. The selection rules corresponding to different transitions between quantum levels are found. The size dispersion distribution of growing quantum dots by the radius and height by two experimentally realizing distribution functions have been taken into account. Distribution functions of Gauss, Lifshits-Slezov have been considered. © 2014 Published by Elsevier Ltd.


Hayrapetyan D.B.,Russian Armenian Slavic University | Hayrapetyan D.B.,State Engineering University of Armenia | Kazaryan E.M.,Russian Armenian Slavic University | Tevosyan H.K.,Russian Armenian Slavic University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2012

In this paper the direct interband light absorption in cylindrical quantum dot with modified Pöschl-Teller potential made of GaAs is studied. For the regime of strong size quantization analytical expressions for the particle energy spectrum, absorption coefficient and dependencies of effective threshold frequencies of absorption on the geometrical sizes of quantum dot are obtained. The selection rules corresponding to different transitions between quantum levels are found. To facilitate the comparison of obtained results with the probable experimental data, size dispersion distribution of growing quantum dots by the geometrical sizes using two experimentally realizing distribution functions has been taken into account. Distribution functions of Lifshits-Slezov and Gaussian have been considered. © 2012 Elsevier B.V.


Dvoyan K.G.,Russian Armenian Slavic University | Dvoyan K.G.,University of Arkansas | Kazaryan E.M.,Russian Armenian Slavic University | Tshantshapanyan A.A.,Russian Armenian Slavic University | And 3 more authors.
Applied Physics Letters | Year: 2011

The electronic states and direct interband absorption of light in quantum dot molecule (QDM) consisting 4 or 5 QDs are investigated. The electron energy levels and wave functions are calculated. It is shown that the energy levels are split in azimuth direction. In the case of the presence of the central QD in QDM an additional splitting in the radial direction is revealed. The suggested method can be used to calculate the electronic states and light absorption of arbitrary number QDM. The results are useful for the application of the QDM to photoelectric devices. © 2011 American Institute of Physics.


Tshantshapanyan A.A.,Russian Armenian Slavic University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

In the framework of adiabatic approximation the energy levels and direct interband absorption of light in the falciform lens shaped quantum dot are studied. Analytical expressions for energy spectrum and wave functions of the electron are obtained. It has been shown, that the particle energy spectrum is equidistant, and dependence of energy on geometrical parameters has root character. Dependences of absorption coefficient and edge frequencies on geometrical parameters of a quantum dot are obtained in the strong quantization regime. Corresponding selection rules for quantum transitions are revealed. © 2012 SPIE.


Dvoyan K.G.,Russian Armenian Slavic University
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2012

In the framework of adiabatic approximation the energy levels and direct interband absorption of light in the ensemble of cylindrical quantum dots' having strongly oblate elliptical cross-section are studied. Analytical expressions for the energy spectrum and wave functions of the electron are obtained. For the "slow" subsystem effective potential approximation, parabolic and modified Poschl-Teller potentials are used. Low-energy levels in the energy spectrum are shown to be equidistant in both cases. Modified Poschl-Teller potential approximation allows taking into account violation of equidistance of energy levels for higher exited states. Absorption coefficient and edge frequencies are obtained in the strong size quantization regime. Corresponding selection rules for quantum transitions are found. © 2012 SPIE.


Gandzhumian V.,Russian Armenian Slavic University
Central Asia and the Caucasus | Year: 2015

The current stage in international relations is characterized by rapid intensification of competition in the energy sphere. The Russian-Ukrainian gas crisis of 2008-2009, as well as the conflict around Ukraine at the current stage are pushing energy supply security, one of the most important concepts in scientific literature, into the foreground. The primary importance of this concept in the increasingly unstable and rapidly changing global economy is promoting the creation of new geopolitical and geo-economic advantages for the transit countries. Moreover, uninterrupted production and safe transportation of oil and natural gas are becoming important for guaranteeing the stability of the largest economies. This article looks at the ways to diversify gas deliveries to Europe, the geopolitical consequences of and Europe’s reaction to implementation of the Turkish Stream gas pipeline, and Turkey becoming the largest transit country and most important gas hub for Europe. Identifying and studying the above topics will be beneficial for drawing up a pragmatic policy that meets current reality. © 2015, CA and CC Press AB. All rights reserved.


Gianjumian V.,Russian Armenian Slavic University
Central Asia and the Caucasus | Year: 2014

The main international actors will pay much more attention to the Central Asian countries as the closest neighbors of Afghanistan, which are unlikely to remain on the periphery of world processes; this has invigorated and will further invigorate their regional activity. oday, the Southern Caucasus is best described as a scene of geopolitical battles among Russia, Turkey, and Iran, as well as between the United States and the European Union. Each of the actors is pursuing its own political interests and nurturing its own ideas about the routes leading to the region’s stability and its incorporation into the world community. To achieve this and to arrive at pragmatic political decisions fully tuned to the geopolitical realities, political scientists and other experts in international relations must study and identify the geopolitical trends prevailing in the Southern Caucasus in the context of Turkish geostrategy in the region. The author analyzes the transformations in Turkey’s foreign policy based on the Zero Problems with Our Neighbors policy formulated by the republic’s former Foreign Minister Ahmet Davutoğlu, which make Turkey’s more active involvement in all spheres of its foreign political activities, building the Ankara-Tbilisi-Baku geopolitical axis as part of the Zero Problems with Our Neighbors policy, and establishing relations with Armenia a far from simple process. The first steps along this road have been taken: Turkey has formulated a Caucasus Stability and Cooperation Platform; Armenia and Turkey have signed a roadmap and the Zurich Protocols (the ratification of which was suspended by the National Assembly of Armenia), while Ankara has been seeking brokerage in the Karabakh conflict.

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