Qasrawı, Atef Fayez Hasan
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Qasrawi, Atef Fayez
Atef Fayez Hasan, Qasrawı
Qasrawı,A.F.H.
Qasrawi,A.F.H.
Q., Atef Fayez Hasan
Q.,Atef Fayez Hasan
Atef Fayez Hasan, Qasrawi
Qasrawi, Atef Fayez Hasan
A.F.H.Qasrawı
A.F.H.Qasrawi
A., Qasrawi
A.,Qasrawı
Qasrawı, Atef Fayez Hasan
Qasrawi, A. F.
Qasrawi,A.F.
Qasrawi, AF
Qasrawi, Atef F.
Qasrawi, Atef A.
Qasrawi, Atef Fayez
Qasrawi, Atef F.
Qasrawi, Atef A.
Qasrawi, Atef
Atef Fayez Hasan, Qasrawı
Qasrawı,A.F.H.
Qasrawi,A.F.H.
Q., Atef Fayez Hasan
Q.,Atef Fayez Hasan
Atef Fayez Hasan, Qasrawi
Qasrawi, Atef Fayez Hasan
A.F.H.Qasrawı
A.F.H.Qasrawi
A., Qasrawi
A.,Qasrawı
Qasrawı, Atef Fayez Hasan
Qasrawi, A. F.
Qasrawi,A.F.
Qasrawi, AF
Qasrawi, Atef F.
Qasrawi, Atef A.
Qasrawi, Atef Fayez
Qasrawi, Atef F.
Qasrawi, Atef A.
Qasrawi, Atef
Job Title
Doçent Doktor
Email Address
atef.qasrawi@atilim.edu.tr
Main Affiliation
Department of Electrical & Electronics Engineering
Status
Former Staff
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7AFFORDABLE AND CLEAN ENERGY
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8DECENT WORK AND ECONOMIC GROWTH
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9INDUSTRY, INNOVATION AND INFRASTRUCTURE
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Scholarly Output
226
Articles
222
Views / Downloads
677/0
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Supervised PhD Theses
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WoS Citation Count
1894
Scopus Citation Count
1915
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0
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0
WoS Citations per Publication
8.38
Scopus Citations per Publication
8.47
Open Access Source
17
Supervised Theses
0
| Journal | Count |
|---|---|
| Crystal Research and Technology | 16 |
| Journal of Electronic Materials | 15 |
| physica status solidi (a) | 12 |
| Materials Science in Semiconductor Processing | 11 |
| Journal of Alloys and Compounds | 11 |
Current Page: 1 / 11
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15 results
Scholarly Output Search Results
Now showing 1 - 10 of 15
Article Citation - WoS: 16Citation - Scopus: 17Dielectric Dispersion in Ga2s3< Thin Films(Springer, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the structural, compositional, optical, and dielectric properties of Ga2S3 thin films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, and ultraviolet-visible light spectrophotometry. The Ga2S3 thin films which exhibited amorphous nature in its as grown form are observed to be generally composed of 40.7 % Ga and 59.3 % S atomic content. The direct allowed transitions optical energy bandgap is found to be 2.96 eV. On the other hand, the modeling of the dielectric spectra in the frequency range of 270-1,000 THz, using the modified Drude-Lorentz model for electron-plasmon interactions revealed the electrons scattering time as 1.8 (fs), the electron bounded plasma frequency as similar to 0.76-0.94 (GHz) and the reduced resonant frequency as 2.20-4.60 x10(15) (Hz) in the range of 270-753 THz. The corresponding drift mobility of electrons to the terahertz oscillating incident electric field is found to be 7.91 (cm (2)/Vs). The values are promising as they nominate the Ga2S3 thin films as effective candidates in thin-film transistor and gas sensing technologies.Article Citation - WoS: 7Citation - Scopus: 7Plasmon-Electron Dynamics at the Au/Inse and Y/Inse Interfaces Designed as Dual Gigahertz-Terahertz Filters(Elsevier Gmbh, Urban & Fischer verlag, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the X-ray diffraction, the Scanning electron microscopy, the energy dispersive X-ray, the Raman, The UV-vis light and the impedance spectral techniques are employed to explore the structural, vibrational, optical and electrical properties of the Au/InSe and Y/InSe thin film interfaces. It was shown that with its amorphous nature of crystallization, the InSe thin films exhibited n-type conductivity due to the 3% excess selenium. For this form of InSe, the only active Raman spectral line is 121 (cm(-1)). In addition to the design of the energy band diagram, the analysis the dielectric spectra and the optical conductivities were possible in the frequency range of 270-1000 THz. The modeling of the optical conductivities of the Au, Y, Au/InSe and Y/InSe with the help of Lorentz approach for optical conduction, assured that the conduction is dominated by the resonant plasmon-electron interactions at the metals and metals/semiconductors interfaces. It also allowed tabulating the necessary parameters for possible applications in terahertz technology: These parameters are the electron effective masses, the free electron densities, the electron bounded plasmon frequencies, the electron scattering times, the reduced resonant frequencies and the drift mobilities. On the other hand, the impedance spectral analysis of the Y/InSe/Au interfaces in the frequency range of 0.01-1.80 GHz, revealed negative capacitance effect associated with band filter features that exhibit maximum transition line at 1.17 GHz. This value nominates the interface as a member of filter classes in the gigahertz technology. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7Design of the Zns/Ge pn Interfaces as Plasmonic, Photovoltaic and Microwave Band Stop Filters(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, we report and discuss the features of the design of a ZnS (300 nm)/Ge (300 nm)/GaSe (300 nm) thin film device. The device is characterized by the X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy (EDS), optical spectroscopy, microwave power spectroscopy and light power dependent photoconductivity. While the X-ray diffraction technique revealed a polycrystalline ZnS coated with two amorphous layers of Ge and GaSe, the hot probe tests revealed the formation of pn interface. The optical spectra which were employed to reveal the conduction and valence band offsets at the ZnS/Ge and Ge/GaSe interface indicated information about the dielectric dispersion at the interface. The dielectric spectra of the ZnS/Ge/GaSe heterojunction which was modeled assuming the domination of surface plasmon interactions through the films revealed a pronounced increase in the drift mobility of free carriers in the three layers compared to the single and double layers. In the scope of the fitting parameters, a wave trap that exhibit filtering properties at notch frequency of 2.30 GHz was designed and tested. The ac signals power spectrum absorption reached similar to 99%. In addition, the photocurrent analysis on the ZnS/Ge/GaSe interface has shown it is suitability for photovoltaic and photosensing applications. (C) 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licenseArticle Citation - WoS: 11Citation - Scopus: 11Optical and Electrical Performance of Yb/Inse Interface(Elsevier Sci Ltd, 2016) Alharbi, S. R.; Qasrawi, A. F.In this study a 300 nm ytterbium transparent thin film is used as substrate to a 300 nm thick InSe thin film. The optical transmittance, reflectance and absorbance of the glass/InSe and Yb/InSe films are measured and analyzed. The optical data allowed determining the effects of the Yb layer on the energy band gap, on the dielectric and on optical conductivity spectra. The band gap of the InSe films shrunk from 2.38/139 to 1.90/1.12 eV upon Yb layer interfacing leading to a band offset of 0.48/0.27 eV. On the other hand, the modeling of the optical conductivity in accordance with the Lorentz theory revealed a free carrier scattering time, carrier density and mobility of 0.225 (fs), 3.0 x 10(19)(cm(-3)) and 2.53 cm(2)/Vs for the Yb/InSe interface, respectively. As these values seem to be promising for employing the Yb/InSe interface in thin film transistor technology, the current voltage characteristics of Yb/InSe/C Schottky diode were recorded and analyzed. The electrical analysis revealed the removal of the tunneling channels by using Yb in place of Al. In addition, the "on/off' current ratios, the Schottky barrier height and the switching voltage of the Yb/InSe/C device are found to be 18.8, 0.76/0.60 eV and 0.53 V, respectively. (C) 2015 Elsevier Ltd. All rights reserved.Article Citation - WoS: 9Citation - Scopus: 8Dielectric dispersion in InSe/CdS bilayers(Elsevier Science Bv, 2018) Qasrawi, A. F.; Shehada, Sufyan R.In the current study, the effect of the amorphous InSe thin film substrate on the structural, optical and dielectric properties of CdS are investigated. The structural analysis of the bilayers indicated a strained growth of CdS onto InSe leading to decrease in grain size and increase in the dislocation density. The optical measurements have shown that the InSe/CdS exhibits two direct allowed transitions energy band gap values of 2.04 and 1.38 eV, in the high and low absorption regions, respectively. On the other hand, the detailed analysis of the dielectric spectra for the InSe, CdS and InSe/CdS layers has shown that the presence of the InSe substrate significantly improves the optical conduction parameters. Particularly, the Drude-Lorentz modeling for these dielectric systems revealed a drift mobility value of 329 cm(2)/V for the InSe/CdS bilayer. The deposition of the CdS onto InSe is also observed to shift the plasmon frequency of CdS from 2.49 to 0.77 GHz. The general features of the InSe/ CdS as plasmon cavities are promising as it shows its usability for production of optoelectronic devices that exhibit high performance at very high frequencies.Article Citation - WoS: 1Citation - Scopus: 1Characterization of the Nanosandwiched Ga2s3< Interfaces as Microwave Filters and Thermally Controlled Electric Switches(Elsevier Gmbh, 2018) Alharbi, S. R.; Nazzal, Eman O.; Qasrawi, A. F.In this work, an indium layer of 50 nm thicknesses is sandwiched between two 500 nm thick Ga2S3 layers. The effect of indium nansandwiching on the composition, structure, morphology, light absorbability, capacitance and reactance spectra, and temperature dependent electrical conductivity of the Ga2S3 films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray spectroscopy, Raman spectroscopy, visible light spectrophotometry, impedance spectroscopy and current voltage characteristics. While the nansandwiched films are observed to exhibit an amorphous nature of structure with indium content of Owing to the nucleation mechanisms that take place during the film growth, the accumulation of some unit cells in groups to form grains should be a significant reason for the existence of many different sizes of grains in the nanosand-wiched films (Alharbi and Qasrawi, 2016). 0, the Raman spectra displayed three vibrational modes at 127.7,145.0 and 274.3 cm(-1). It was also observed that the indium insertion in the structure of the Ga2S3 shrinks the energy band gap by 0.18 eV. The nanosandwiched films are observed to exhibit a semiconductor metal (SM) transition at 310 K. The SM transition is associated with thermal hysteresis that exhibited a maximum value of 16% at 352 K. This behavior of the nanosandwiched films nominate it for use as thermally controlled electric switches. In addition, the impedance spectral analysis in the range of 10-1800 MHz has shown a capacitance tunability of more than 70%. The measurements of the wave trapping property displayed a bandpass/reject filter characteristics above 1.0 GHz which allow using the Ga2S3/In/Ga2S3 thin films as microwave resonator. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 3Citation - Scopus: 3Optical Analysis of Ge/Mgo and Ge/Bn Thin Layers Designed for Terahertz Applications(Elsevier Sci Ltd, 2015) Al Garni, S. E.; Qasrawi, A. F.In this work, a 200 nm Ge thin film is used as a substrate to design Ge/MgO and Ge/BN layers. The optical dynamics in these devices are investigated by means of the reflectivity and the transmissivity measurements. Particularly, the details of the dielectric spectra and the values of the energy band gaps (E-g) are investigated. Below 350 THz, the construction of Ge/MgO and Ge/BN interfaces decreased the effective dielectric constant of Ge by 39% and by 76%, respectively. It also increased the quality factor of the Ge optical device from 150 to 1400 and to 940 at 300 THz. All the dispersive optical parameters are also evaluated. In addition, the direct/indirect E-g value of Ge which was determined as 1.15/0.72 eV is observed to shift down by a 0.13/0.42 and by a 023/0.54 eV for the Ge/MgO and Ge/BN devices, respectively. The sharp increase in the dielectric constant with decreasing frequency in the range of 353 273 THz, the dispersive optical parameters and the energy band gap attenuations of the optical structures are promising as they indicate the applicability of the Ge, Ge/MgO and Gel BN layers in terahertz sensing. The latter technology has a wide range of applications like medical and telecommunication devices. (C) 2014 Elsevier Ltd. All rights reserved.Article Citation - WoS: 2Citation - Scopus: 2Enhancement of Photoconductive Performance of Cdse Via Yb Nanosandwiching(Elsevier Gmbh, Urban & Fischer verlag, 2018) Qasrawi, A. F.In this work, we have explored the effects of the ytterbium nanosandwiching on the structural and optoelectronic properties of CdSe thin films. A ytterbium layer of thickness of 200 nm was sandwiched between two layers of CdSe (1.0 mu m). The structural investigations have shown that the hexagonal structure of CdSe is deformed by 1.9% and 0.8% along the a and c - axes, respectively, by the inclusion of the Yb in the structure of CdSe. In addition, a systematic redshifts in the interference patterns of the optical transmittance and reflectance were observed. Accordingly, the optical absorption coefficient spectra of CdSe which displayed two energy gap values of 1.62 and 1.36 eV, are also redshifted. On the other hand, when exposed to blue light irradiation, the steady state and time dependent photocurrent analysis revealed a remarkable enhancement presented by a three orders of magnitude increase in the responsivity of CdSe upon Yb sandwiching. The photocurrent was observed to be limited by the saturation of the surface states and traps that causes longer relaxation constant compared to that of pure CdSe. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 21Engineering the Optical and Dielectric Properties of the Ga2s3< Nanosandwiches Via Indium Layer Thickness(Springer, 2018) Nazzal, Eman O.; Qasrawi, A. F.; Alharbi, S. R.In this study, the effect of the nanosandwiched indium slab thickness (20-200 nm) on the performance of the Ga2S3/In/Ga2S3 interfaces is explored by means of X-ray diffraction, Raman spectroscopy, and optical spectroscopy techniques. The indium slab thickness which was varied in the range of 20-200 nm is observed to enhance the visible light absorbability of the Ga2S3 by 54.6 times, engineered the energy band gap in the range of 3.7-1.4 eV and increases the dielectric constant without, significantly, altering the structure of the Ga2S3. The broad range of the band gap tunability and the increased absorbability nominate the Ga2S3 thin films for photovoltaic applications. In addition, the dielectric spectral analysis and modeling have shown that a wide variety in the plasmon resonant frequency could be established within the Ga2S3/In/Ga2S3 trilayers. The plasmon frequency engineering in the range of 0.56-2.08 GHz which is associated with drift mobility of 12.58-5.76 cm(2)/Vs and electron scattering time at femtosecond level are promising for the production of broad band high frequency microwave filters.Article Citation - WoS: 11Citation - Scopus: 11Post Annealing Effects on the Structural, Compositional, Optical and Dielectric Properties of Cd Doped Gase Thin Films(Elsevier Science Sa, 2015) Al Garni, S. E.; Qasrawi, A. F.In this work, the heat treatment effects at temperatures (T-a) of 200, 300 and 400 degrees C on the compositional, structural, optical and dielectric properties of Cd doped GaSe are explored by means of energy dispersive X-ray spectroscopy, X-ray diffraction and UV-VIS spectrophotometry. The annealing process of the Cd doped GaSe thin films revealed a highly oriented orthorhombic structure type that exhibit a systematic increase in the grain size. While the strain, degree of orientation and dislocation density of the annealed films are weakly affected by the annealing process. The optical energy band gap of the doped films decreased from 1.23 to 0.90 eV and the exponential energy band tails rose from 0.16 to 0.23 eV when the annealing temperature is raised from 300 to 400 degrees C. In addition, the analysis of the dielectric spectral curves which were studied in the frequency range of 270-1500 THz, allowed to investigate the oscillator and dispersion energies and the static (epsilon(s)) and lattice (epsilon(l)) dielectric constants. The annealing process on the doped samples decreased the dispersion and oscillator energies as well as es. Oppositely, el values increased from 12.52 to 24.45 as a result of larger grain size and less defect density associated with annealing process when T-a is raised from 200 to 400 degrees C, respectively. (C) 2015 Elsevier B.V. All rights reserved.
