Kayed, Tarek Said
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Kayed, Tarek S.
T.,Kayed
K., Tarek Said
T.S.Kayed
Kayed, Tarek Said
T., Kayed
Tarek Said, Kayed
K.,Tarek Said
Kayed,T.S.
Kayed, TS
Kayed, T. S.
Kayed, TS
T.,Kayed
K., Tarek Said
T.S.Kayed
Kayed, Tarek Said
T., Kayed
Tarek Said, Kayed
K.,Tarek Said
Kayed,T.S.
Kayed, TS
Kayed, T. S.
Kayed, TS
Job Title
Doçent Doktor
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Main Affiliation
Department of Electrical & Electronics Engineering
Status
Former Staff
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Scholarly Output
25
Articles
22
Views / Downloads
82/0
Supervised MSc Theses
0
Supervised PhD Theses
0
WoS Citation Count
205
Scopus Citation Count
214
Patents
0
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0
WoS Citations per Publication
8.20
Scopus Citations per Publication
8.56
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0
Supervised Theses
0
| Journal | Count |
|---|---|
| Crystal Research and Technology | 5 |
| Materials Research Bulletin | 2 |
| Journal of Alloys and Compounds | 2 |
| Journal of Electronic Materials | 2 |
| physica status solidi (b) | 2 |
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25 results
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Now showing 1 - 10 of 25
Article Citation - WoS: 5Citation - Scopus: 6Structural, Optical, Dielectric and Electrical Properties of Al-Doped Znse Thin Films(Springer, 2019) Kayed, T. S.; Qasrawi, A. F.; Elsayed, Khaled A.In this work, the heavy aluminum doping effects on the compositional, structural, optical, dielectric and electrical properties of ZnSe thin films are investigated. It is observed that the Zn/Se compositional ratio increases with increasing Al content. The major cubic phase of ZnSe becomes more pronounced compared to the hexagonal phase. In addition, the presence of Al in the structure of ZnSe causes lattice constant contraction, decreased the grain size and increased both of the strain and defect density. Optically, the Al doping increased the light absorbability and widens both of the energy band gap and energy interbands which are present in the band gap of ZnSe films. Moreover, the Al doping into ZnSe lowers the high frequency dielectric constant and enhances the optical conductivity. On the other hand, the capacitance spectra which are studied in the frequency domain of 0.01-1.80GHz displayed negative capacitance effect associated with resonance-antiresonance phenomena upon doping of ZnSe with Al. Such enhancements in the physical properties of ZnSe that are achieved via Al doping make the zinc selenide thin films more appropriate for electronic and optoelectronic technological applications.Article Citation - WoS: 9Citation - Scopus: 9Electrical Properties of Bi1.5znsb1.5< Pyrochlore Ceramics(Wiley-v C H verlag Gmbh, 2003) Kayed, TS; Mergen, ABi1.5ZnSb1.5O7 pyrochlore samples were prepared by solid state reaction method. They were examined by x-ray diffraction and scanning electron microscopy. Single phase, belongs to the cubic pyrochlore structure, with a lattice parameter of 10.442 Angstrom and grain size that varies from 16 to 20 mum was obtained. The electrical properties were measured at different temperatures in the range 15-330 K under different applied magnetic fields up 1.4 T. In our measurements for Hall coefficient, Hall resistivity, and mobility; we noticed an anomalous behavior at two temperatures (around 250 and 310 K) which was supported by the I-V measurements (double transition of the slope of I-V characteristics (beta) at the same temperatures). This was discussed in terms of polarization phenomenon and mixed ionic-electronic conduction. (C) 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Article Citation - WoS: 7Citation - Scopus: 9Properties of Boron Doped Ti-Ba Superconductors(Pergamon-elsevier Science Ltd, 2003) Kayed, TSThe effects of boron doping on the formation and properties of the Tl-based superconductors have been studied. Up to 10 wt.% boron has been added to the oxides having the nominal composition, Tl1.8Ba2Ca2.2Cu3Ox, by the usual solid-state reaction method. Boron additions in the range 0.8-1.0% increase the fraction of the Tl-2223 phase and significantly improve the critical temperature of the samples. Higher amounts of boron additions eliminate the Tl-2223 phase, reduce the fraction of Tl-2212 phase and cause separate non-superconducting phases to be formed. The formation of non-superconducting phases does not allow us to obtain pure Tl-2212 phase. (C) 2002 Elsevier Science Ltd. All rights reserved.Conference Object Citation - WoS: 10Production of Anorthite From Kaolinite and Caco3 Via Colemanite(Trans Tech Publications Ltd, 2004) Mergen, A; Kayed, TS; Bilen, M; Qasrawi, AF; Gürü, MBoron oxide has been found to be useful flux for the preparation of dense anorthite ceramics (CaO.Al2O3.2SiO(2)). Inexpensive starting materials of kaolinite, calcium carbonate and silica were used for anorthite ceramic production. Colemanite (2CaO.3B(2)O(3).5H(2)O) was added into the mixtures and the effects of colemanite upon the transformation towards anorthite and on the densification were investigated between 900-1400 degreesC. Single phase anorthite ceramic formed at lower temperatures in boron containing mixtures. Boron containing powder compacts were sintered above 90% theoretical density at 1350 degreesC.Article Citation - WoS: 18Citation - Scopus: 19Heat Treatment Effects on the Structural and Electrical Properties of Thermally Deposited Agin5s8< Thin Films(Pergamon-elsevier Science Ltd, 2011) Qasrawi, A. F.; Kayed, T. S.; Ercan, FilizThe heat treatment effects on structural and electrical properties of thermally deposited AgIn5S8 thin films have been investigated. By increasing the annealing temperature of the sample from 450 to 500 K, we observed a change in the crystallization direction from (420) to (311). Further annealing of the AgIn5S8 films at 550, 600 and 650 K resulted in larger grain size in the (311) preferred direction. The room temperature electrical resistivity, Hall coefficient and Hall mobility were significantly influenced by higher annealing temperatures. Three impurity levels at 230, 150, and 78 meV were detected for samples annealed at 350 K. The electrical resistivity decreased by four orders of magnitude when the sample annealing temperature was raised from 350 to 450 K. The temperature dependent electrical resistivity and carrier concentration of the thin film samples were studied in the temperature ranges of 25-300 K and 140-300 K, respectively. A degenerate-nondegenerate semiconductor transition at approximately 180 was observed for samples annealed at 450 and 500 K. Similar type of transition was observed at 240 K for samples annealed at 600 and 650 K. (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7Photoconductivity Kinetics in Agin5s8< Thin Films(Elsevier Science Sa, 2010) Qasrawi, A. F.; Kayed, T. S.; Ercan, Ismail; Ercan, SmailThe temperature (T) and illumination intensity (F) effects on the photoconductivity of as grown and heat-treated AgIn5S8 thin films has been investigated. At fixed illumination intensity, in the temperature region of 40-300K, the photocurrent (I-ph) of the films was observed to decrease with decreasing temperature. The I-ph of the as grown sample behaved abnormally in the temperature region of 170-180K. At fixed temperature and variable illumination intensity, the photocurrent of the as grown sample exhibited linear, sublinear and supralinear recombination mechanisms at 300 K and in the regions of 160-260K and 25-130 K. respectively. This behavior is attributed to the exchange of role between the linear recombination at the surface near room temperature and trapping centers in the film which become dominant as temperature decreases. Annealing the sample at 350 K for 1 h improved the characteristic curves of I-ph. The abnormality disappeared and the I-ph - T dependence is systematic. The data analysis of which revealed two recombination centers located at 66 and 16 meV. In addition, the sublinear recombination mechanism disappeared and the heat-treated films exhibited supralinear recombination in most of the studied temperature range. (C) 2010 Elsevier B.V. All rights reserved.Article Citation - WoS: 5Citation - Scopus: 5Electrical Behavior of Pb1.83mg0.29< Pyrochlore Ceramics(Elsevier Science Bv, 2004) Mergen, A; Kayed, TSPb1.83Mg0.29Nb1.71O6.39 pyrochlore was produced via a simple partial oxalate method. It was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Single phase, belonging to the cubic pyrochlore structure, with a lattice parameter of a = 10.60125 +/- 0.001 Angstrom and grain size that varies from 5 to 10 mum was obtained. The electrical properties were measured at different temperatures in the range 15-320 K without and with applied magnetic field of 1.4 T. Current-voltage characteristics data were fitted to a power law expression V=I-beta(T) in which the exponential parameter beta takes values around 1 at all temperatures except at 300 K. Resistance starts from 3.3 x 10(10) Omega at 15 K and increases gradually to 4.8 x 10(10) Omega at 240 K. It drops to approximately 1.2 x 10(10) Omega at 300 K, after which it increases again to around 1.6 x 10(10) Omega at 320 K. (C) 2004 Elsevier B.V. All rights reserved.Article Citation - WoS: 42Citation - Scopus: 41Synthesis and Characterization of Mg2b2<(Pergamon-elsevier Science Ltd, 2005) Qasrawi, AF; Kayed, TS; Mergen, A; Gürü, MMagnesium borate of the form Mg2B2O5 has been prepared and its structural and thermal properties were studied using X-ray diffraction and differential thermal analysis. An investigation of the electrical and optical properties of Mg2B2O5 system has been carried out. The electrical resistivity of the sample was measured in the temperature range of 170-400 K. The data analysis revealed an extrinsic nature of the conductivity with two impurity levels located at 0.13 and 0.71 eV in the temperature ranges of 170-230 K and 240-400 K, respectively. The optical transmission and reflection was recorded at 300 K in the incident photon energy range of 3.0-6.0 eV. The absorption coefficient data analysis revealed an indirect optical energy band gap of 4.73 eV. In addition, two impurity levels located at 3.43, and 4.49 eV were observed in the absorption spectra. (c) 2005 Elsevier Ltd. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3Characterization of As2se3< Heterojunction Designed for Multifunctional Operations(Iop Publishing Ltd, 2021) Qasrawi, A. F.; Kayed, T. S.In this article, As2Se3/MoO3 heterojunction devices are structurally, compositionally, optically and electrically characterized. The heterojunction devices which are prepared by the thermal evaporation technique under vacuum pressure of 10(-5) mbar are observed to exhibit amorphous nature of growth. The optical spectrophotometry measurements and analyses on the heterojunction devices revealed a conduction and valence band offsets of values of 2.64 and 4.08 eV, respectively. In addition, the dielectric dispersion and the optical conductivity parametric analyses have shown that the heterojunction could exhibit large drift mobility value up to 73.7 cm(2) V-1 s(-1). From electrical point of view, while the capacitance- voltage curves reveal characteristics of MOSFET devices, the current--voltage curves display tunneling diode characteristics. The features of the As2Se3/MoO3 devices including the band offsets, drift mobility, plasmon frequency, microwave band filtering and MOSFET characteristics make them attractive for use as thin films transistors suitable electrical and optical applications.Article Citation - WoS: 2Citation - Scopus: 2Voltage-Current Characteristics of Bi-2223 Superconducting Tape Near Tc Under Γ Irradiation(Wiley-v C H verlag Gmbh, 2004) Kayed, TS; Ercan, IVoltage-current characteristics at four different applied magnetic fields (7, 20, 30, and 40 mT) of Bi2Sr2Ca2CU3Ox superconducting tape were measured in the temperature range from 100 to 115 K. They were also measured at zero magnetic field before and after gamma irradiations up to 10 MRad at different temperatures just below the critical temperature. The data were fitted to a power law expression V = I (beta(T)) in which the exponential parameter P under 20 mT field and after irradiation is found to fluctuate around three and then drops to unity near the critical temperature which may be interpreted as a sign of Kosterlitz-Thouless transition. The electrical properties of the tape were found to be very sensitive to gamma irradiation where most of the changes take place in low gamma doses.
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