Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Keyword
-
- Thin films (18)
- Optical properties (12)
- Solar cell (10)
- ZnO (10)
- Chalcogenide glasses (9)
-
- Thermodynamics (8)
- Cosmology (7)
- DFT (7)
- Density functional theory (7)
- Lattice parameter (7)
- Band gap (6)
- Elastic scattering (6)
- Electrical properties (6)
- Energy levels (6)
- Phase transition (6)
- Photoconductivity (6)
- Quantum well (6)
- Spray pyrolysis (6)
- X-ray diffraction (6)
- Bulk modulus (5)
- Cosmic ray (5)
- Decoherence (5)
- Dirac equation (5)
- Diurnal (5)
- Electrical conductivity (5)
- Entropy (5)
- Nanoparticles (5)
- Nuclear structure (5)
- Quantum dot (5)
- Schrödinger equation (5)
- Publication Year
Articles 1201 - 1230 of 1374
Full-Text Articles in Physical Sciences and Mathematics
Silicon-Based Optoelectronics: Progress And Challenges, Tamim P. Sidiki, Clivia M. Sotomayor Torres
Silicon-Based Optoelectronics: Progress And Challenges, Tamim P. Sidiki, Clivia M. Sotomayor Torres
Turkish Journal of Physics
We review the status of silicon-based optoelectronics with emphasis on light emitting diodes. Erbium-doped Si, por-Si and silicon-based superlattices and nanostructures are discussed. The origin behind light emission in silicon with feature sizes below about 60 nm still remains poorly understood.
An Investigation Of Electrical Properties Of Porous Silicon, G. Algün, M. Ç. Arikan
An Investigation Of Electrical Properties Of Porous Silicon, G. Algün, M. Ç. Arikan
Turkish Journal of Physics
In this work, electrical properties of porous silicon structures, formed with electrochemical anodization in HF acid solution under two different current densities, were investigated. In these experiments, Sb doped (111)-oriented n-type silicon samples with 0.006-0.015 \Omega cm resistivity was used. Samples were anodized in a solution of 38% HF and 99% C_2H_2OH at 1:1 ratio for 15 minutes. After anodization, the structures that formed at low current density (J = 5 mA/cm^2) was compared with structures that formed at high current density (J = 30 mA/cm^2). Both structures and electrical properties were investigated.
Interference Of Charged Particles In A Vector Potential With Vanishing Magnetic Field, İsmai̇l Hakki Duru
Interference Of Charged Particles In A Vector Potential With Vanishing Magnetic Field, İsmai̇l Hakki Duru
Turkish Journal of Physics
An interference experiment in a magnetic field free region with non vanishing vector potential created by two perpendicularly intersecting planes carrying uniform currents is discussed. The relation of this configuration to the Aharonov-Bohm potential is examined. An experimental set up which is finite in the direction of electronic motion is studied.
Elementary Charges In Classical Electrodynamics, Edward Kapuscik, Maciej Widomski
Elementary Charges In Classical Electrodynamics, Edward Kapuscik, Maciej Widomski
Turkish Journal of Physics
In the framework of classical electrodynamics elementary particles are treated as capacitors. The electrostatic potentials satisfy equations of the Schrödinger type. An interesting "quantization condition" for elementary charges is derived.
Medium-Dependent Metric In Electrostatics, Bernard Jancewicz
Medium-Dependent Metric In Electrostatics, Bernard Jancewicz
Turkish Journal of Physics
The use of differential forms allows the formulation of the principal equations of electrodynamics in a metric-independent way. The metric is needed only for finding the solutions. Various metrics can be introduced, depending on the medium. A special metric, connected with the electric permittivity tensor, allows us to reduce all electrostatic problems in anisotropic media to those in in isotropic one.
The Wigner Problem In Electrodynamics, Andrzej Horzela
The Wigner Problem In Electrodynamics, Andrzej Horzela
Turkish Journal of Physics
The relation between canonical commutation rules and a shape of acting force is analysed. It is shown that canonical commutation relations and Newtonian equations of motion for a single particle dynamics do imply the force to be of the Lorentz type but the inverse is not true. The example of a single particle motion in a constant magnetic field shows that equations of motion allow an alternative to canonical commutation relations to exist and it is a Lie algebra. The algebra found is of the type of algebras found in studies leading towards noncommutative geometry approaches to physical problems.
A New Formalism For Nonextensive Physical Systems: Tsallis Thermostatistics, Uğur Tirnakli, Fevzi Büyükkiliç, Doğan Demi̇rhan
A New Formalism For Nonextensive Physical Systems: Tsallis Thermostatistics, Uğur Tirnakli, Fevzi Büyükkiliç, Doğan Demi̇rhan
Turkish Journal of Physics
Although Boltzmann-Gibbs (BG) statistics provides a suitable tool which enables us to handle a large number of physical systems satisfactorily, it has some basic restrictions : (i) the range of the microscopic interactions must be small compared to the linear size of the macroscopic systems (short-range interactions) , (ii) the time range of the microscopic memory must be small compared to the observation time (Marcovian processes) and (iii) the system must evolve in an Euclidean-like space-time. In the case of a breakdown in one and/or the others of these restrictions, BG statistics fails. More precisely, the situation could be classified …
Electron Liquid Beyond The Random Phase Approximation, Mehmet Tomak, Ceyhun Bulutay
Electron Liquid Beyond The Random Phase Approximation, Mehmet Tomak, Ceyhun Bulutay
Turkish Journal of Physics
A deeper understanding of low-dimensional and small-scale electronic systems requires an accurate characterization of the many-electron effects. Based on the electron liquid (EL) model, these many-body effects in the three-dimensional (3D) and two-dimensional (2D) electronic systems are dealt going beyond the random phase approximation within the zero-temperature framework. The dielectric formulation of the many-body problem is recapitulated and the longitudinal dielectric function of the EL is obtained using the self-consistent local-field correction scheme, known as STLS, under a general spin-valley degeneracy. Extensive explicit expressions are provided for the use of other researchers. The performance of this formalism is compared in …
Short-Period Rs Cvn And W Uma Binaries: How Are They Related?, Frans Van't Veer
Short-Period Rs Cvn And W Uma Binaries: How Are They Related?, Frans Van't Veer
Turkish Journal of Physics
Two groups of late-type very close main sequence binaries, the so-called short-period RS Canum Venaticorum (RS CVn) and W Ursae Majoris (W UMa) systems, are important for the understanding of the structure and evolutionary consequencies of angular momentum loss (AML) resulting from magnetic stellar winds of fast rotating solar type stars. The components of RS CVn stars are close to their Roche lobes, but still detached, whereas W UMa binaries are contact systems; both are rotating fast. One of the crucial problems is trying to answer the question if there is a dynamical relation between the two types of binaries …
Orbital Period Modulation In Chromospherically Active Close Binaries, Cafer İbanoğlu
Orbital Period Modulation In Chromospherically Active Close Binaries, Cafer İbanoğlu
Turkish Journal of Physics
The orbital period changes in some chromospherically active close binaries have been interpreted as a consequence of magnetic activity. At least in two active close binaries a possible relationship between the orbital period modulation and activity cycle was suggested. The existence of a third companion in these binaries has also been proposed. The light-time effect which arises from orbiting around a third-body has been subtracted from all the O-C values and a cyclic change of the orbital period has been obtained. These cyclic changes seem to be connected with the total brightness variations at least in two samples, namely, V471 …
Three-Channel General-Purpose Astrophotometer, Romualdas Kalytis
Three-Channel General-Purpose Astrophotometer, Romualdas Kalytis
Turkish Journal of Physics
The high-speed three-channel photometer suitable for the time-series observations of the "Whole Earth Telescope" (WET) project as well as for multicolor photometry is described. The photometer, designed for the Capodimonte Astronomical Observatory, Italy, is the latest version of the WET photometers developed by the WET group of Vilnius University since 1992. The main optical and mechanical layouts of the optico-mechanical module as well as the block-diagram of electronics are presented. The main specifications of the photometer expected after its completion are given.
Photometric Imaging Of Starspots, Techniques And Reliability, Zeki̇ Eker
Photometric Imaging Of Starspots, Techniques And Reliability, Zeki̇ Eker
Turkish Journal of Physics
Historical development of the starspot hypothesis and the unsolved problems associated with it are presented. The "non{uniqueness" attributed to the spot solutions is a major problem which could still discredit current efforts of starspot modeling by photometric or spectroscopic data. The basics of the starspot photometry(direct and inverse photometric problem, and the error analysis of the inverse problem) are presented. Since an analytical formulation exists to compute synthetic light curves from the physical parameters of spots, and recomputing original parameters analytically from the synthetic curves are also possible, the starspot hypothesis is a consistent physical problem. According to the error …
Facular Structures On Cool Stars, Serdar Evren
Facular Structures On Cool Stars, Serdar Evren
Turkish Journal of Physics
Activity has many manifestations, from dark spots to bright regions, to the presence of the heated chromosphere, to the superheated corona. Sunspots are extended, strongly magnetic regions on the Sun. Photospheric faculae are generally visible only at the limb. Polar faculae are smaller than the main-zone faculae. The contributions of the active region faculae and the facular network are at least as important as the solar spots in augmenting the solar emission.
Solar Flares, E. Rennan Pekünlü
Solar Flares, E. Rennan Pekünlü
Turkish Journal of Physics
In this paper, the dynamics, the magnetohydrodynamics and the energetics of flaring magnetic loops are reviwed. It is also emphasized that the presented model is in no way a unique one. The most commonly occurring type is labelled as B type flares. This paper reviews the general features of a B type flare.
The Structure Of Liquid Alkali Metals Calculated By The Thermodynamic Perturbation Theory, H. Bi̇rtan Kavanoz, İdri̇s Gümüş
The Structure Of Liquid Alkali Metals Calculated By The Thermodynamic Perturbation Theory, H. Bi̇rtan Kavanoz, İdri̇s Gümüş
Turkish Journal of Physics
The structure of a hard sphere fluid has been calculated numerically via the Percus-Yevick (PY) and hypernetted-chain (HNC) closure relations and used as a reference system to calculate the structure of liquid alkali metals under the optimized random-phase approximation (ORPA) using the effective ion-ion pair potential formed by the Heine-Abarenkov (HA), and the empty-core (EC) pseudopotentials. The results are compared with experimental results. The calculations made by the reference system under the HNC closure relation are in better agreement with experimental results than those found under the PY closure relation.
Ionizing Radiations And Annealing Influence On Mosfet Charge States, Zainabidinov Ciragiddin, Atamuratov Atabek, Ysupov Akhmed, Adinaev Kuvondik
Ionizing Radiations And Annealing Influence On Mosfet Charge States, Zainabidinov Ciragiddin, Atamuratov Atabek, Ysupov Akhmed, Adinaev Kuvondik
Turkish Journal of Physics
The threshold voltage shift \Delta V_T and its components due to trapped-oxide charges \Delta V_{Not} and Si-SiO_2 interface traps \Delta V_N in MOSFET exposed to Bremsstrahlung, Co_{60} irradiation and annealing were studied. Several effects caused by differences in the photon energies from two types of sources are discussed as well as a mechanism of changing the trapped-oxide and Si-SiO_2 interface traps by annealing. The mechanism is based on previously available models.
Calibration Of Millimetric Marmara Radio Telescope And Radio Detection Of Ozone Line Over Gebze/Kocaeli In Turkey, Mehmet Emi̇n Özel, I. M. Yusifov, A. O. Allakhverdiev, A. A. Vertiy, G. Bayer, Osman Demi̇rcan, H. Kirbiyik, T. Adigüzel
Calibration Of Millimetric Marmara Radio Telescope And Radio Detection Of Ozone Line Over Gebze/Kocaeli In Turkey, Mehmet Emi̇n Özel, I. M. Yusifov, A. O. Allakhverdiev, A. A. Vertiy, G. Bayer, Osman Demi̇rcan, H. Kirbiyik, T. Adigüzel
Turkish Journal of Physics
A brief description of the calibration procedures for the millimetric Marmara Radio Telescope, MRT-2 is presented. Observations carried out during the spectroscopic calibration work is indicative of daily variations of Ozone line of sight density over the telescope location. This being also the first radio observations carried out in Turkey, a short account of observations and results are given.
Energetics Of Spherical Clusters, Hati̇ce Kökten, Şaki̇r Erkoç
Energetics Of Spherical Clusters, Hati̇ce Kökten, Şaki̇r Erkoç
Turkish Journal of Physics
The energetics of spherical clusters of elements Fe in bcc, Ca and Pb in fcc, and C in diamond structure have been investigated by using emprical many-body potential energy function which contains two- and three-body inteactions. In the variation of average interaction energy per atom (E_b) versus cluster size (N_{sh}; number of shells) only carbon clusters have magic numbers at 5, 8, 11 and 14 shells. E_b versus N_{sh} becomes smooth after 15 shells for carbon, however this variation becomes smooth for the other elements after 10 shells. The variation of two-body to three-body interaction energy versus cluster size becomes …
Electrons And Phonons In Gan Semiconductor Quantum Well Devices, M. Babiker, N. A. Zakhleniuk, C. R. Bennett, V. N. Stavrou, B. K. Ridley
Electrons And Phonons In Gan Semiconductor Quantum Well Devices, M. Babiker, N. A. Zakhleniuk, C. R. Bennett, V. N. Stavrou, B. K. Ridley
Turkish Journal of Physics
Electrons and polar optical phonons and their interactions are considered in the context of semiconductor quantum well devices, with particular reference to real quantum well laser structures. Distinction is made between wide-barrier and narrow-barrier structures and we explore the implications of these regimes for the description of the electron capture process. Special emphasis is made on the significant effects arising from the large effective mass ratio in AlN/GaN structures.
Coherent Control Experiments As A Probe Of The Carrier Scattering Processes, P. Le Jeune, X. Marie, T. Amand, M. Paillard, J. Barrau
Coherent Control Experiments As A Probe Of The Carrier Scattering Processes, P. Le Jeune, X. Marie, T. Amand, M. Paillard, J. Barrau
Turkish Journal of Physics
We report on coherent control experiments of excitons in GaAs/AlGaAs Quantum wells.This technique, which relies on the linear response of the crystal,is used to investigate the spin-dependent exciton-exciton scattering.
Novel Detectors And Lasers For Telecommunications, Anthony J. Vickers, Hamid R. Mashayekhi, Pattara Aiyarak, Diego Oriato
Novel Detectors And Lasers For Telecommunications, Anthony J. Vickers, Hamid R. Mashayekhi, Pattara Aiyarak, Diego Oriato
Turkish Journal of Physics
For the most part the field of optoelectronics has been dominated by the pn junction for both detector and laser applications. This domination will probably hold true for laser applications for many more years although the simple forward biased junction may be challenged by other novel approaches as increased complexity is required such as multi-wavelength emission, wavelength conversion, and Thz operation. The first real novel use of the pn junction was developed by Balkan et al. [1]. Their HELLISH device paved the way for novel approaches in the use of the pn junction. In this paper I shall introduce another …
3 \Mu M Intersubband Quantum Well Photodetector (Qwip), Rita Gupta, A. L. Y. Wong, S. K. Haywood
3 \Mu M Intersubband Quantum Well Photodetector (Qwip), Rita Gupta, A. L. Y. Wong, S. K. Haywood
Turkish Journal of Physics
In recent years photodetectors operating in the mid- to far infrared region of 3-15 \mu m have been designed based on electron and hole intersubband transitions in multiple quantum wells and superlattices. In general, QWIPs based on electron transitions show greater detectivity compared to the hole-based photodetectors. However, selection rules for electron intersubband transitions usually forbid the TE mode operation, associated with normal light incidence; Therefore, special coupling structures/geometries have been employed to couple light into the device. The spectral region 3-5 \mu m is of interest for a variety of applications such as environmental gas sensing, thermal imaging etc. …
Single Si \Delta-Doped Gaas Investigations By New Photothermal Wavelength Modulated Photocurrent Technique, Fi̇kret Hajiev, Yener Özkan, M. Çeti̇n Arikan
Single Si \Delta-Doped Gaas Investigations By New Photothermal Wavelength Modulated Photocurrent Technique, Fi̇kret Hajiev, Yener Özkan, M. Çeti̇n Arikan
Turkish Journal of Physics
New Photothermal Wavelength Modulated Photocurrent (PWMPC) technique is reported. This technique is used for investigation of the MBE grown p-GaAs sample in which a single Si-layer was embedded with a \delta-type profile. Two spectral features were observed at 1.5137 eV and 1.5115 eV at 20 K. These peaks were attributed to the (D°,X) and (A°,X)-excitons bound to neutral donors and acceptors, respectively. We studied the temperature dependence of these excitonic peaks positions at temperatures between 20-90 K. Additionally, we demonstrate a blue shift of photocurrent spectra under a low level illumination intensity. PWMPC technique and the nature of the registered …
Improvement In Electroabsorption And The Effect Of The Electric Field In The Tuneable Wavelength Converter, Hüseyi̇n Sari, Esi̇n Kasapoğlu, Yüksel Ergün, İsmai̇l Sökmen
Improvement In Electroabsorption And The Effect Of The Electric Field In The Tuneable Wavelength Converter, Hüseyi̇n Sari, Esi̇n Kasapoğlu, Yüksel Ergün, İsmai̇l Sökmen
Turkish Journal of Physics
The numerical results of the study of a novel wavelength converter which can be tuned with the application of an external field are presented. For this device, exciton binding energies, radiuses and the absorption coefficient are numerically analysed as a function of electric field. We showed that the interband transition energy and the overlap function between electron and hole changes abruptly when an electric field is applied. This phenomenon can be used the increase the change in the absorption coefficient and reduce the on-state transmission loss in electroabsorption modulators.
A Gainasp/Inp Vertical Cavity Surface Emitting Laser For 1.5 \Mu M Operation, R. Sceats, N. Balkan, M. J. Adams, J. Masum, A. J. Dann, S. D. Perrin, I. Reid, J. Reed, P. Cannard, M. A. Fisher, D. J. Elton, M. J. Harlow
A Gainasp/Inp Vertical Cavity Surface Emitting Laser For 1.5 \Mu M Operation, R. Sceats, N. Balkan, M. J. Adams, J. Masum, A. J. Dann, S. D. Perrin, I. Reid, J. Reed, P. Cannard, M. A. Fisher, D. J. Elton, M. J. Harlow
Turkish Journal of Physics
We present the results of our studies concerning the pulsed operation of a bulk GaInAsP/InP vertical cavity surface emitting laser (VCSEL). The device is tailored to emit at around 1.5 \mu m at room temperature. The structure has a 45 period n-doped GaInAsP/InP bottom distributed Bragg reflector (DBR), and a 4 period Si/Al_2O_3 dielectric top reflector defining a 3-\lambda cavity. Electroluminescence from a 16 \mu m diameter top window was measured in the pulsed injection mode. Spectral measurements were recorded in the temperature range between 125K and 240K. Polarisation, lasing threshold current and linewidth measurements were also carried out at …
Multitime Generalization Of Maxwell Electrodynamics And Gravity, Vladilen Barashenkov
Multitime Generalization Of Maxwell Electrodynamics And Gravity, Vladilen Barashenkov
Turkish Journal of Physics
System of equations of motion for interacting electromagnetic field and charged bodies is derived by means of an action principle in six-dimensional space with a three-dimensional time vector. The influence of the additional (hidden) components of time on the body motion is considered. Macroscopic experiments and astrophysical observations which can reveal the time multi-dimensionality are discussed. At present there are no facts which would be in contradiction with the hypothesis of the multi-dimensionality of time.
The Concept Of Free Electromagnetic Field In Quantum Domain, Alexander Shumovsky, Özgür Müstecaplioğlu
The Concept Of Free Electromagnetic Field In Quantum Domain, Alexander Shumovsky, Özgür Müstecaplioğlu
Turkish Journal of Physics
By virtue of the consideration of polarization and phase properties of dipole radiation in the quantum domain, it is shown that the concept of free electromagnetic field should be considered as a quite risky approximation in the description of quantum fluctuations of some physical observables.
Quantum Mechanics Of The Electric Charge, Andrzej Staruszkiewicz
Quantum Mechanics Of The Electric Charge, Andrzej Staruszkiewicz
Turkish Journal of Physics
The Author summarizes the evidence that his quantum theory of the electric charge depends in a nontrivial way on the numerical value of the fine structure constant.
Two-Level Atom In A Squeezed Vacuum, Ryszard Tanas
Two-Level Atom In A Squeezed Vacuum, Ryszard Tanas
Turkish Journal of Physics
The master equation for a two-level atom interacting with a strong coherent field and damped into a reservoir formed by a finite bandwidth squeezed vacuum is derived. The master equation extends the Yeoman and Barnett approach to a non-zero detuning of the driving field from the atomic resonance and allows to discuss the role of squeezing bandwidth and the detuning in the level shifts, widths and intensities of spectral lines. The approach is valid for arbitrary values of the Rabi frequency and detuning but for the squeezing bandwidths larger than the natural linewidth in order to satisfy the Markov approximation.
Electromagnetic Waves In Disordered Dielectric Media: Coupled-Dipole Model, Arkadiusz Orlowski, Marian Rusek
Electromagnetic Waves In Disordered Dielectric Media: Coupled-Dipole Model, Arkadiusz Orlowski, Marian Rusek
Turkish Journal of Physics
An effective approach to multiple scattering of electromagnetic waves by disordered dielectric media is developed. A self-consistent energy-conserving coupled-dipole model is used. Applications to the Anderson localization of electromagnetic waves are presented. A complete set of Maxwell's equations is used to describe the propagation of waves and the vector character of the electromagnetic field is fully taken into account.