Profile URL: https://hdl.handle.net/20.500.14411/7716
Job Title:Doçent Doktor
Email Address:atef.qasrawi@atilim.edu.tr
Main Affiliation:Department of Electrical & Electronics Engineering
Status: Former Staff
Name Variants:
Qasrawi, Atef Fayez Atef Fayez Hasan, Qasrawı
232 results
Scholarly Output Search Results
Now showing 1 - 10 of 232
Article Citation - WoS: 10Citation - Scopus: 11Dispersive Optical Constants of Thermally Deposited Agin<sub>5</Sub>s<sub>8< Thin Films(Elsevier Science Sa, 2008-01) Qasrawi, A. F.Agln(5)S(8) thin films were obtained by the thermal evaporation of Agln(5)S(8) crystals onto ultrasonically cleaned glass substrates. The films are found to exhibit polycrystalline cubic structure. The calculated lattice parameter of the unit cell (a) is 10.78 angstrom. The transmittance data of the as grown films which was recorded at 300 K in the incidence wavelength (lambda) range of 320-1000 nm are used to calculate the refractive, n(lambda). The transmittance and reflectance data are also used to calculate the absorption coefficient of the as grown Agln5S8 thin films. The fundamental absorption edge is found to be corresponding to a direct allowed transitions energy band gap. This band-to-band transition energy is found to be 1.78 eV and it is consistent with that reported for Agln(5)S(8) single crystals. (c) 2007 Elsevier B.V. All rights reserved.Article Citation - WoS: 13Citation - Scopus: 15Performance of the Au/Mgo Photovoltaic Devices(Elsevier Sci Ltd, 2015-01) Khanfar, H. K.; Qasrawi, A. F.A 100 mu m thick MgO film is used to design a metal semiconductor metal device. The device is characterized by means of current voltage characteristics in the dark and under various light energies in the photon energy range of 3.70-2.15 eV. A photovoltaic effect presented by an open circuit voltage of 0.12-0.47 V. short circuit current density of 3.9-10.5 mu A/cm(2), quantum efficiency of 0.662-0.052, and responsivity of 0.179-0.024 A/W under photoexcitation optical power of 2.2-28.2 mu W is observed. The device was also tested as a UV optical communication component. The test revealed a wide range of tunability and sensitivity for microwave resonant frequencies of 0.5 and 2.9 GHz. The differential resistance of the device exhibited different values at each applied ac signal frequency. When the frequency is fixed, the illuminated to the dark current ratio remained constant for all signal powers in the range of 0.00-20.0 dBm. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 9Transient and Steady State Photoelectronic Analysis in Tlinse<sub>2</Sub> Crystals(Pergamon-elsevier Science Ltd, 2011-08) Qasrawi, A. F.; Gasanly, N. M.The temperature and illumination effects on the transient and steady state photoconductivities of TlInSe2 crystals have been studied. Namely, two recombination centres located at 234 and at 94 meV and one trap center located at 173 meV were determined from the temperature-dependent steady state and transient photoconductivities, respectively. The illumination dependence of photoconductivity indicated the domination of sublinear and supralinear recombination mechanisms above and below 160 K, respectively. The change in the recombination mechanism is attributed to the exchange of roles between the linear recombination at the surface and trapping centres in the crystal, which become dominant as temperature decreases. The transient photoconductivity measurement allowed the determination of the capture coefficient of traps for holes as 3.11 x 10(-22) cm(-2). (C) 2011 Elsevier Ltd. All rights reserved.Article Citation - WoS: 19Citation - Scopus: 20Heat Treatment Effects on the Structural and Electrical Properties of Thermally Deposited Agin<sub>5</Sub>s<sub>8< Thin Films(Pergamon-elsevier Science Ltd, 2011-04) 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: 5Citation - Scopus: 5Dispersive Optical Constants of Tl<sub>2</Sub>ingase<sub>4< Single Crystals(Iop Publishing Ltd, 2007-07-27) Qasrawi, A. F.; Gasanly, N. M.The structural and optical properties of Bridgman method grown Tl2InGaSe4 crystals have been investigated by means of room temperature x-ray diffraction, and transmittance and reflectance spectral analysis, respectively. The x-ray diffraction technique has shown that Tl2InGaSe4 is a single phase crystal of a monoclinic unit cell that exhibits the lattice parameters of a = 0.77244 nm, b = 0.64945 nm, c = 0.92205 nm and beta = 95.03 degrees . The optical data have revealed an indirect allowed transition band gap of 1.86 eV. The room temperature refractive index, which was calculated from the reflectance and transmittance data, allowed the identification of the dispersion and oscillator energies, static dielectric constant and static refractive index as 28.51 and 3.45 eV, 9.26 and 3.04, respectively.Article Citation - WoS: 11Citation - Scopus: 12Effect of Au Nanosandwiching on the Structural, Optical and Dielectric Properties of the as Grown and Annealed Inse Thin Films(Elsevier Science Bv, 2017-09) Omareya, Olfat A.; Qasrawi, A. F.; Al Garni, S. E.In the current work, the structural, optical and dielectric properties of the InSe/Au/InSe nanosandwiched structures are investigated by means of X-ray diffraction and UV-visible light spectrophotometry techniques. The insertion of a 20 and 100 nm thick Au metal slabs between two InSe layers did not alter the amorphous nature of the as grown InSe films but decreased the energy band gap and the free carrier density. It also increased; the absorption ratio and the values of dielectric constant by similar to 3 times. The insertion of 100 nm Au layers as a nanosandwich enhanced the drift mobility (31.3 cm(2)/V s) and plasmon frequency (1.53 GHz) of the InSe films. On the other hand, upon annealing, a metal induced crystallization process is observed for the InSe/Au (100 nm)/InSe sandwiches. Particularly, while the samples sandwiched with a layer of 20 nm thickness hardly revealed hexagonal gamma -In2Se3 when annealed at 300 degrees C, those sandwiched with 100 nm Au slab, displayed well crystalline phase of hexagonal gamma -In2Se3 at annealing temperature of 200 degrees C. The further annealing at 300 degrees C, forced the appearing of the orthorhombic In4Se3 phase. Optically, the annealing of the InSe/Au(100 nm)/InSe at 200 degrees C improved the absorption ratio by similar to 9 times and decreased the energy band gap. The nanosandwiching technique of InSe seems to be promising for the engineering of the optical properties of the InSe photovoltaic material.Article Citation - WoS: 6Citation - Scopus: 6Design and characterization of (Al, C)/p-Ge/p-BN/C isotype resonant electronic devices(Wiley-v C H verlag Gmbh, 2015-05-19) Al Garni, S. E.; Qasrawi, A. F.In this work, a Ge/BN isotype electronic device that works as a selective microwave bandstop filter is designed and characterized. The interface is designed using a 50-m thick p-type BN on a 0.2-m thick p-type germanium thin film. The modeling of current-voltage characteristics of the Al/Ge/BN/C channel of the device revealed that the current is dominated by thermionic emission and by the tunneling of charged particles through energy barriers. The evaluation of the conduction parameters reflected a resonant circuit with a peak-to-valley current ratio of (PVCR) of 63 at a peak (V-p) and valley (V-v) voltages of 1.84 and 2.30V, respectively. The ac signal analysis of the Al/Ge/BN/C channel that was carried out in the frequency range of 1.0-3.0GHz displayed a bandstop filter properties with notch frequency (f(n)) of 2.04GHz and quality factor (Q) of 102. The replacement of the Al electrode by C through the C/Ge/BN/C channel caused the disappearance of the PVCR and shifted f(n) and Q to 2.70GHz and 100, respectively. The features of the Ge/BN device are promising as they indicate the applicability of these sensors in communication technology.Article Citation - WoS: 4Citation - Scopus: 5Electrical Characterization of Bi<sub>1.50-<i>x</I>< Varactors(World Scientific Publ Co Pte Ltd, 2014-08) Qasrawi, A. F.; Abu Muis, Khalil O.; Abu Al Rob, Osama H.; Mergen, A.; Muis, Khalil O. Abu; Al Rob, Osama H. AbuThe electrical properties of yttrium doped bismuth zinc niobium oxide (BZN) pyrochlore ceramics are explored by means of temperature dependent electrical conductivity dielectric constant and capacitance spectra in the frequency range of 0-3 GHz. It is observed that the doped BZN exhibit a conductivity type conversion from intrinsic to extrinsic as the doping content increased from 0.04 to 0.06. The thermal energy bandgap of the intrinsic type is 3.45 eV. The pyrochlore is observed to exhibit a dielectric breakdown at 395 K. In addition, a negative capacitance (NC) spectrum with main resonance peak position of 23.2 MHz is detected. The NC effect is ascribed to the increased polarization and the availability of more free carriers in the device. When the NC signal amplitude is attenuated in the range of 0-20 dBm at 50 MHz and 150 MHz, wide tunability is monitored. Such characteristics of the Y-doped BZN are attractive for using them to cancel the positive parasitic capacitance of electronic circuits. The canceling of parasitic capacitance improves the high frequency performance of filter inductors and reduces the common mode noise of the resonance signal.Article Carrier Transport Properties of Ins Single Crystals(2002) Qasrawi,A.F.; Gasanly,N.M.The electrical resistivity and Hall effect of indium sulfide single crystals are measured in the temperature range from 25 to 350 K. The donor energy levels located at 500, 40 and 10 meV below the conduction band are identified from both measurements. The data analysis of the temperature-dependent Hall effect measurements revealed a carrier effective mass of 0.95 m0, a carrier compensation ratio of 0.9 and an acoustic deformation potential of 6 eV. The Hall mobility data are analyzed assuming the carrier scattering by acoustic and polar optical phonons, and ionized impurities.Article Citation - WoS: 27Citation - Scopus: 30Effects of Au Nanoslabs on the Performance of Cdo Thin Films Designed for Optoelectronic Applications(Elsevier, 2021-01) Alharbi, Seham Reef; Qasrawi, A. F.In this work, the effect of 50 nm thick gold nanosheets on the structural, morphological, optical and electrical properties of stacked layers of CdO are investigated. The insertion of Au nanoslabs decreased the lattice parameters of the cubic unit cells of CdO. It also decreased the microstrain, the defect density, the stacking fault percentage and increased the crystallite and grain sizes. Optically, the light absorbability is enhanced, the energy band gap is shrunk and the optical conductivity is increased. The optical conductivity parameters presented by scattering time, plasmon frequency, drift mobility and free carrier density are all engineered via participation of Au nanosheets. On the other hand, electrical measurements in the frequency domain of 0.01-1.80 GHz indicated that the Au nanosheets forced the capacitance spectra to exhibit negative values and increased the electrical conductivity in the studied frequency domain. The terahertz cutoff frequency is tuned in the range of 5.0-22.0 THz indicating the applicability of the CdO/Au/CdO (CAC) films as terahertz filters. The direct current electrical conductivity measurements have shown that while the CC samples exhibit nondegenerate extrinsic nature of conduction, the CAC samples displayed degenerate/nondegenerate transitions at 400 K. With the feature of negative capacitance that can be used for noise reduction and parasitic capacitance cancellation, the CAC films can be regarded as promising structure for multifunctional device applications.
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| Journal | Count |
|---|---|
| Crystal Research and Technology | 17 |
| Journal of Electronic Materials | 15 |
| physica status solidi (a) | 12 |
| Materials Science in Semiconductor Processing | 11 |
| Journal of Alloys and Compounds | 11 |
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Scholarly Output
232
Articles
228
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160/0
Supervised MSc Theses
0
Supervised PhD Theses
0
WoS Citation Count
2016
Scopus Citation Count
2035
Patents
0
Projects
0
WoS Citations per Publication
8.69
Scopus Citations per Publication
8.77
Open Access Source
18
Supervised Theses
0
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