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Articles 8521 - 8550 of 8705
Full-Text Articles in Entire DC Network
Fundamental Research And Device Technology, B. K. Ridley
Fundamental Research And Device Technology, B. K. Ridley
Turkish Journal of Physics
Highlights of the interaction between fundamental research and semiconductor device technology are summarized.
Electron Transport In Gaas Quantum Wells: Effect Of Interface Roughness Scatterin, Rita Gupta
Electron Transport In Gaas Quantum Wells: Effect Of Interface Roughness Scatterin, Rita Gupta
Turkish Journal of Physics
The importance of interface roughness (IFR) scattering of electrons and LO-phonons for electron transport in semiconductor quantum wells is discussed. Modulation doping of quantum wells minimizes the effect of impurity scattering on the low-field electron mobility so that IFR scattering of electrons in the well becomes the major limiting factor. A model calculation of IFR scattering of electrons in quantum wells is presented and it is shown that (both)\Lambda and \Delta, the parameters defining IFR, can be estimated by comparing the theoretical and experimental electron mobilities. The application of high electric field leads to a distribution of hot electrons which …
Feasibility Of The Gainp/Ingaas/Gaas System For Modulation Doped Field-Effect Transistors, C. Besi̇kci̇, Y. Ci̇van
Feasibility Of The Gainp/Ingaas/Gaas System For Modulation Doped Field-Effect Transistors, C. Besi̇kci̇, Y. Ci̇van
Turkish Journal of Physics
Si-doped single Ga_{0.51}In_{0.49}P layers and GaInP/InGaAs/GaAs modulation doped field-effect transistor structures grown by gas source molecular beam epitaxy were characterized in detail through Hall-Effect and Deep Level Transient Spectroscopy techniques. Electrical characterization of the undoped and moderately Si-doped (N_D = 3 x 10^{17} cm^{-3}) GaInP layers yielded an electron trap with an activation energy of 0.75 eV and a temperature dependent capture cross section with a capture barrier of 0.593 eV showing DX center properties. The trap was not detected in highly Si doped (N_D = 4 x 10^{18} cm^{-3}) as grown layers suggesting that it is a defect complex …
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.
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. …
Hellish-Vcsel: A Hot Electron Laser, A. Obrien-Davies, N. Balkan, A. Boland-Thoms, M. J. Adams, J. Roberts
Hellish-Vcsel: A Hot Electron Laser, A. Obrien-Davies, N. Balkan, A. Boland-Thoms, M. J. Adams, J. Roberts
Turkish Journal of Physics
Hot Electron Light emission and Lasing In Semiconductor Heterostructures (HEL-LISH-1) is a novel hot electron surface emitter consisting of a GaAs QW on the n side of an Ga_{1-x}Al_xAs p-n junction. It utilises hot electron transport parallel to the junction plane. The injection of hot electron hole pairs into the QW is achieved via tunnelling and thermionic emission processes. Recently this structure has been modified by the incorporation of an upper and lower DBR defining a VCSEL (HELLISH-VCSEL). This has been shown to lase at room temperature with a Full Width at Half Maximum (FWHM) of 1.5 nm. In this …
The Effect Of Non-Equilibrium Acoustic Phonons On The Tunnel Current In Gaas/Alas Superlattices, S. A. Cavill, F. F. Ouali, L. J. Challis, A. J. Kent, M. Henini, A. V. Akimov
The Effect Of Non-Equilibrium Acoustic Phonons On The Tunnel Current In Gaas/Alas Superlattices, S. A. Cavill, F. F. Ouali, L. J. Challis, A. J. Kent, M. Henini, A. V. Akimov
Turkish Journal of Physics
We present the first study of the effect of ballistic acoustic phonons generated by a heated metal film on the tunnel current in GaAs/AlAs superlattices. The phonon-induced increase of the tunnel current as a function of applied voltage has a maximum at a voltage that varies linearly with heater temperature both in zero and applied magnetic field. The behaviour is consistent with phonon-assisted tunnelling by stimulated phonon emission. The system acts as a phonon spectrometer in the < 1THz frequency region with a resolution of approximately 200 GHz.
Carrier Transport And Band Offsets In Two Dimensional Heterostructures, Hi̇lmi̇ Ünlü
Carrier Transport And Band Offsets In Two Dimensional Heterostructures, Hi̇lmi̇ Ünlü
Turkish Journal of Physics
Advances in the low dimensional heterojunction device technology cannot be complete without adequate and reliable analytic model for determining interface properties such as band offsets needed to study the carrier transport and to evaluate the device performance at high temperatures and pressures. In this article, using the extended universal tight binding model of semiconductors, a new way of determining the band offsets in heterostructures is presented. In this model the band offsets are first determined by aligning the vacuum level, defined relative to valence band maximum which is screened by optical dielectric constant of semiconductors, at the interface at absolute …
Influence Of Electrical Field On Pulsed Laser Beam Welding Of Stainless Steel (304), Salah A. H. Fawzi̇, Raz N. Ari̇f
Influence Of Electrical Field On Pulsed Laser Beam Welding Of Stainless Steel (304), Salah A. H. Fawzi̇, Raz N. Ari̇f
Turkish Journal of Physics
Pulsed laser beam welding experiment were carried out on stainless steel (SUS 304), using vertical and horizontal electric fields of different intensities to study its effectiveness on the welding process, regarding depth and weld quality. Pulsed Nd: YAG laser emitting 10 ms pulses in the TEM_{00} mode at 1.06 \mu m wave length was employed, microstructure of welded zone and defect were investigated using optical and scanning electron microscopes. Tensile test and microhardness measurements were carried out to evaluate the weld quality. Welding by this method increased the efficiency tremendously and a depth increase of 85% was achieved.
Prevalence Of Enzootic Bovine Leukosis In The South Marmara Region And Observations Of Some Management Practices, Hasan Batmaz, K. Tayfun Çarli, Ayşi̇n Şen, Engi̇n Kennerman, Ahmet Mi̇nbay, Zeki̇ Yilmaz, Vi̇ldan Caner, Can Baklaci
Prevalence Of Enzootic Bovine Leukosis In The South Marmara Region And Observations Of Some Management Practices, Hasan Batmaz, K. Tayfun Çarli, Ayşi̇n Şen, Engi̇n Kennerman, Ahmet Mi̇nbay, Zeki̇ Yilmaz, Vi̇ldan Caner, Can Baklaci
Turkish Journal of Veterinary & Animal Sciences
Seven hundred seventeen cattle, over the age of six months in the South Marmara Region (Bursa, Balıkesir and Çanakkale) were tested for the presence of Bovine Leukemia Virus (BLV)-antibody with ELISA.Blood and milk samples were taken from 362 and 355 cattle, respectively. Totally, sixty-nine cattle (9.62%) were found to be carriers of antibodies against BLV-gp 51 antigen.The BLV infection rate was found to be 13.25% and 5.91% in the sera and milk samples tested, respectively. The infection rate were determined to be 14.19 % in Bursa and 3.52 % in Balıkesir, but BLV seropositive cattle were not found in Çanakkale. …
Cover And Contents
Turkish Journal of Veterinary & Animal Sciences
No abstract provided.
Quality Changes Of Scad (Trachurus Trachurus) Which Are Stored Under Different Chillingconditions And Freezing At-12 °C, Mehmet Demi̇rci̇, H. Hülya Orak
Quality Changes Of Scad (Trachurus Trachurus) Which Are Stored Under Different Chillingconditions And Freezing At-12 °C, Mehmet Demi̇rci̇, H. Hülya Orak
Turkish Journal of Agriculture and Forestry
In this study was aimed some quality changes and determitation of shelf life of scad (Trachurus trachurus)using different chilling methods and freezing temperature at -12 °C were investigated. Scad (Trachurus trachurus) stored different conditions and different temperature as, in sea water ice and water ice at -1 °C, sea water + sea ice at + 1 °C, water and water ice at + 1 °C and also freezing at -12 °C. In addition to sensory chracteristics also pH, trimethylamine (TMA), total volatile basic ammonia (TVB-N), thiobarbituric (TBA), peroxide value and ammonia, were determined. The results of labratory analysis indicated that …
Production Of Susy Particles In Polarized \Gammap Collisions, A. Kandemi̇r
Production Of Susy Particles In Polarized \Gammap Collisions, A. Kandemi̇r
Turkish Journal of Physics
We discuss the production of several SUSY particles in the high energy collisions of the real photons off the protons within the MSSM. The polarizations of the colliding beams are also considered. The discovery mass limits for the squark and gluinos are presented and we conclude that the capacity of the future TeV scale $\gamma p$ colliders is quite promising in the search for SUSY particles.
Glycoprotein Iib/Iiia Inhibitors In Acute Coronarysyndromes: A New Paradigm In Cardiology, Mehmet Ağirbaşli, David M. Kerins
Glycoprotein Iib/Iiia Inhibitors In Acute Coronarysyndromes: A New Paradigm In Cardiology, Mehmet Ağirbaşli, David M. Kerins
Turkish Journal of Medical Sciences
No abstract provided.
The Determination Of Thermal Annealing Effect On The Dos Profile Of A-Si:H Film, Tülay Seri̇n
The Determination Of Thermal Annealing Effect On The Dos Profile Of A-Si:H Film, Tülay Seri̇n
Turkish Journal of Physics
In this study the aim was to investigate the effect of thermal annealing on the density of states (DOS) of hydrogenated amorphous silicon (a-Si:H) by means of a Schottky structure. In order to realize that goal the sandwich structured Au/a-Si:H/a-Si:H(n$^+$-type)/Cr Schottky diode was fabricated. The junction capacitance of the samples were measured as a function of the amplitude of alternating voltage in the frequency range of 500 Hz - 100 KHz and in the annealing temperature range of 23 - 175^oC. The density of states profile as a function of both annealing temperature and energy were plotted. The effect of …
Current-Voltage Characteristics And Photoresponse Of Metal Metal Devices, K. Singh, S.N.A. Hammond
Current-Voltage Characteristics And Photoresponse Of Metal Metal Devices, K. Singh, S.N.A. Hammond
Turkish Journal of Physics
Thin films (35 \AA) of $Al_2O_3$ on glass slides have been used for the fabrication of $Al/Al_2O_3/Al, Ag/Al_2O_3/Al$ and $Cu/Al_2O_3/Al$ devices. The room temperature current-voltage characteristics and the dependence of current densities of these devices at various wavelength $(\lambda)$ of light were measured. The results obtained on current density and photocurrent show that $Al_2O_3$ films have the potential for wider applications like antireflective coatings or treatments in photovoltaic devices, transparent insulation materials, and optical trapping surfaces in many electronic devices.
Physics At Hera+Lc Based \Gammap Colliders, Z. Z. Aydin
Physics At Hera+Lc Based \Gammap Colliders, Z. Z. Aydin
Turkish Journal of Physics
In this proceeding I discuss the proposal of constructing a $\gamma p$ collider at DESY based on a Linac-Ring type $ep$ machine, the HERA+LC. A high energy $\gamma$ beam for this collider is produced by the Compton back-scattering of laser photons off the electron beam from the linear accelerator. Using the parameters of the proton ring of HERA and those of the proposed linear $e^{+}e^{-}$ colliders (LC, specifically TESLA, CLIC or Linac1) we expect a luminosity of $L_{\gamma p} =(1-2)\times 10^{31} cm^{-2} s^{-1}$, due to a reasonable improvement of the proton beam. We examine the physics research program for the …
Symmetry Of C_{60} And A Force Constant Model For Vibrational Modes, Ramazan Koç, Hayriye Tütüncüler
Symmetry Of C_{60} And A Force Constant Model For Vibrational Modes, Ramazan Koç, Hayriye Tütüncüler
Turkish Journal of Physics
A force-constant model for the vibrational modes in $C_{60}$ is presented. The Keating type potential is adopted for calculating the dynamical matrix. Using symmetries of the molecule, the dynamical matrix which yields the vibrational modes is block-diagonalized. We summarize the role of group theory in specifying the vibrational modes. The results are in excellent agreement with experiments. The effect of bond-stretching force constants on the vibrational modes will be presented.
An Analysis Of The Variation In Calculated Confined-State Energies Using Different Envelope-Function Models, Beşire Gönül
An Analysis Of The Variation In Calculated Confined-State Energies Using Different Envelope-Function Models, Beşire Gönül
Turkish Journal of Physics
We investigate different formulations of the envelope-function method and show that the accuracy of the calculated zone-centre confinement energies can be calculated by means of bulk band structure. We show how coupling to the conduction and spin-split-off bands can decrease the light-hole zone-centre confinement energies and lead to significant differences in the calculated subband dispersion.
Economic Analysis And Comparison Of Two Solar Energy Systems With Domestic Water Heating Systems, R. Kayali
Economic Analysis And Comparison Of Two Solar Energy Systems With Domestic Water Heating Systems, R. Kayali
Turkish Journal of Physics
In this work, an economic analysis of different types of thermosiphons and geysers and flat plate collectors and solar ponds employeed in conventional solar energy systems used in houses is analized and the results obtained for these systems are compared with each other. These comparisons show that when the inflation rate is 50\% or less solar energy systems are more economical than the other conventional systems, except for conventional systems in which solid fuels are used. If the calculations are done assuming that the consumer credit interest rate varies between 55-70\%, it is seen that solar energy systems will only …
Domain Structures Of Epitaxial Perovskite Ferroelectric Films: Part I. Theory, S. Pamir Alpay, Alexander L. Roytburd
Domain Structures Of Epitaxial Perovskite Ferroelectric Films: Part I. Theory, S. Pamir Alpay, Alexander L. Roytburd
Turkish Journal of Physics
Possible equilibrium domain structures due to elastic interactions between the film and the substrate as a result of a cubic-tetragonal transformation observed in epitaxial perovskite ferroelectric films are analyzed. Domain structures are compared in terms of their elastic energies. The formation of both two- and three-domain states is taken into account. Maps which shows domain stability regions are developed in coordinates of misfit strain and tetragonality of the lattice of the ferroelectric phase.
Crystal Data For A_3b_5c_9-Type Ternary Compounds, Hüsnü Özkan, Nizami Gasanly, İbrahim Yilmaz, Ali Çulfaz, Vyaceslav Nagiev
Crystal Data For A_3b_5c_9-Type Ternary Compounds, Hüsnü Özkan, Nizami Gasanly, İbrahim Yilmaz, Ali Çulfaz, Vyaceslav Nagiev
Turkish Journal of Physics
X-ray powder diffraction data were obtained for Cu$_3$Ga$_5$Se$_9$, Cu$_3$In$_5$Se$_9$, Cu$_3$In$_5$Te$_9$, Ag$_3$In$_5$S$_9$, Ag$_3$Ga$_5$S$_9$, Ag$_3$In$_5$Se$_9$, and Ag$_3$Ga$_5$Te$_9$ ternary compounds. The data indicate that these compounds crystallize in orthorhombic, monoclinic, orthorhombic, monoclinic, tetragonal, tetragonal, and orthorhombic systems, respectively.