Qasrawı, Atef Fayez Hasan

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https://hdl.handle.net/20.500.14411/7716
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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
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Doçent Doktor
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atef.qasrawi@atilim.edu.tr
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Department of Electrical & Electronics Engineering
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Former Staff
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Scholarly Output

226

Articles

222

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677/0

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WoS Citation Count

1894

Scopus Citation Count

1915

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WoS Citations per Publication

8.38

Scopus Citations per Publication

8.47

Open Access Source

17

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0

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Crystal Research and Technology16
Journal of Electronic Materials15
physica status solidi (a)12
Materials Science in Semiconductor Processing11
Journal of Alloys and Compounds11
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Start date: 2010Subject: X-ray diffraction

Scholarly Output Search Results

Now showing 1 - 10 of 12
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    Article
    Citation - WoS: 3
    Citation - Scopus: 3
    Ytterbium Induced Structural Phase Transitions and Their Effects on the Optical and Electrical Properties of Znpc Thin Films
    (Springer, 2020) Qasrawi, A. F.; Zyoud, Hadeel M.
    In this work, the effects of ytterbium substrates of thicknesses of 150 (Yb-150) and 1000 nm (Yb-1000) on the structural, optical and electrical properties of zinc phthalocyanine (ZnPc) are investigated. While the Yb-150/ZnPc exhibited strained monoclinic structure, the Yb-1000/ZnPc thin films are observed to exhibit phase transitions from monoclinic to triclinic structure. Analysis which targeted observatories of the effects of the Yb-150 substrate on the optical properties indicated that the transparent Yb-150 substrate enhanced the light absorbability by more than 11 times at 1.27 eV. On the other hand, the impedance spectroscopy measurements on the nontransparent Yb-1000/ZnPc/Ag sandwiched structures have shown that these devices could exhibit negative capacitance (NC) effect in the frequency domain of 0.244-1.800 GHz. The NC effect is associated with resonance-anti-resonance response at 0.235 and 0.244 GHz, respectively. The structural, optical and electrical properties of the Yb/ZnPc interfaces indicate its applicability as optoelectronic and/or radio/microwave components.
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    Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Structural and Dielectric Properties of Ba1-x< Solid Solutions
    (Wiley-v C H verlag Gmbh, 2021) Qasrawi, A. F.; Sahin, Ethem Ilhan; Abed, Tamara Y.; Emek, Mehriban
    Herein, lanthanum doping effects on the structural, dielectric, and electrical properties of Ba1-xLax(Zn1/3Nb2/3)O-3 (BZN) solid solutions are focused upon. The La contents which are varied in the range of 0.02-0.20 exhibit a solubility limit of x = 0.02. Although minor phases of Ba5Nb4O15 and Ba3LaNb3O12 appear for samples doped with La contents of x = 0.05 and x = 0.10, they play no remarkable role for the enhanced structural and dielectric properties of BZN. The La doping content of x = 0.02 succeeds in increasing the crystallite size by 51.16% and lowering the microstrain by 34.18% and defect concentration by 63.10%. La-doped BZN ceramics display higher values of relative density and electrical conductivity. The analyses of the dielectric spectra as a function of temperature display dielectric relaxation behavior above 120 degrees C. In the temperature range of 20-120 degrees C, La doping changes the temperature coefficient of dielectric constants from +30 ppm degrees C-1 in pure samples to -341 ppm degrees C-1 in samples doped with La contents of x = 0.10. The enhancements in structural parameters, density values, and dielectric responses that are achieved via La doping make BZN ceramics more suitable for electronic device fabrication.
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    Article
    Citation - WoS: 7
    Citation - Scopus: 7
    Photoconductivity Kinetics in Agin5s8< Thin Films
    (Elsevier Science Sa, 2010) Qasrawi, A. F.; Kayed, T. S.; Ercan, Ismail; Ercan, Smail
    The 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.
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    Article
    Citation - WoS: 5
    Citation - Scopus: 4
    Thickness and Annealing Effects on the Structural and Optical Conductivity Parameters of Zinc Phthalocyanine Thin Films
    (inst Materials Physics, 2020) Alharbi, S. R.; Qasrawi, A. F.; Khusayfan, N. M.; Department of Electrical & Electronics Engineering
    In this work, the effects of the thin film thicknesses on the structural, optical absorption, energy band gap, dielectric spectra and optical conductivity parameters of the Zinc phthalocyanine thin films are considered. Thin films of ZnPc of thicknesses of 50-600 nm which are coated onto glass substrates are observed to exhibit amorphous nature of growth. The polycrystalline monoclinic ZnPc phase of the films is obtained via annealing the films at 200 degrees C in a vacuum atmosphere. Increasing the ZnPc films thickness shrunk the energy band gap in the B- and Q- bands and decreased both of the optical conductivities and free holes density in the Q-band. The increase in the film thickness is also observed to decrease the plasmon frequency and the drift mobility of holes in the films. The highest dielectric constant is obtained for films of thicknesses of 100 nm. The annealing process enhanced the optical absorption, redshifts the energy band gap value and the critical energy of the absolute maxima of dielectric constant. In addition, while the heat treatment enhanced both of the scattering times at femtosecond level and the drift mobility, it reduced the free holes density, and the plasmon frequency.
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    Article
    Citation - WoS: 4
    Citation - Scopus: 4
    Optical Dynamics at the Au/Znpc Interfaces
    (Univ Fed Sao Carlos, dept Engenharia Materials, 2020) Qasrawi, A. F.; Zyoud, Hadeel M.
    In this work, the optical dynamics and the structural properties of the zinc phthalocyanine which are coated onto 150 nm thick Au substrates are studied by the X-ray diffraction and optical spectrophotometry techniques. The Au/ZnPc interfaces appears to be strongly affected by the large lattice mismatches at the interface. It is observed that the coating ZnPc onto Au substrates increases the light absorbability by 4.7 and 128.2 times in the visible and infrared regions of light, respectively. Au substrates activated the free carrier absorption mechanism in the ZnPc thin films in the infrared range of light. In addition, the transparent Au substrates forced narrowing the energy band gap in both of the Q and B bands. It also increased the dielectric constant value by similar to 3.5 times in the IR range. The enhancements in the optical properties of ZnPc that resulted from the thin Au substrates make the ZnPc more suitable for optoelectronic, nonlinear optical applications and for electromagnetic energy storage in the infrared range of light.
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    Article
    Citation - WoS: 21
    Citation - Scopus: 21
    Design and Characterization of Moo3 Heterojunctions
    (Elsevier Science Bv, 2019) Al Garni, S. E.; Qasrawi, A. F.
    In this work, the morphological, compositional, structural, optical and dielectric properties of CdSe which are deposited onto glass and onto MoO3 thin film substrates are investigated. The use of MoO3 as substrate for the growth of CdSe is observed to increase the lattice parameters of the hexagonal unit cell of CdSe and decreases the values of grain size and strain. It also forms band tails of width of 0.20 eV in the band gap of CdSe. The optical analysis has shown that the MoO3/CdSe interfacing results in blue shift in the energy band gap of CdSe and also result in large conduction and valence band of sets of values of 2.12 and 0.94 eV, respectively. The dielectric spectral analysis with the help of Prude-Lorentz approaches for optical conduction, revealed an enhancement in the drift mobility of charge carriers from 15.69 to 39.30 cm(2)/V as a response to the incident electromagnetic field. The free carrier density of the MoO3/CdSe being of the order of 10(17) cm(-3) with the large valence and conduction band offsets and the sufficiently large drift mobility nominates the MoO3/CdSe heterojunctions as an effective component of optoelectronic technology including thin film transistors.
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    Article
    Citation - WoS: 10
    Citation - Scopus: 9
    Tunable Au/Ga2< Varactor Diodes Designed for High Frequency Applications
    (Natl inst R&d Materials Physics, 2017) Al Garni, S. E.; Qasrawi, A. F.; Department of Electrical & Electronics Engineering
    In this work, the design and characterization of Au/Ga2S3/Yb Schottky barrier is investigated by means of transmittance electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDXS), capacitance spectroscopy, capacitance (C)-voltage (V) characteristics and impedance spectroscopy techniques. The design of the energy band diagram of the amorphous Au/Ga2S3 interface revealed a theoretical energy barrier height (q phi(b)) and built in voltage (qV(bi)) of 2.04 and 1.88 eV, respectively. Experimentally, the qV(bi) was observed to be sensitive to the applied signal frequency. In addition, the capacitance spectra which were studied in the range of 10-1800 MHz, revealed resonance and antiresonance biasing dependent signal oscillations associated with negative capacitance values. On the other hand, impedance spectroscopy analysis revealed band pass/reject filtering properties in all the studied frequency range. The device exhibited a return loss, voltage standing wave ratio and power efficiency of 16.7 dB, 1.3 and 98.3% at 1400 MHz, respectively.
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    Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Formation and Negative Capacitance Effect in Au/Bi2< Heterojunctions Designed as Microwave Resonators
    (Natl inst R&d Materials Physics, 2018) Al Garni, S. E.; Qasrawi, A. F.; Department of Electrical & Electronics Engineering
    In this article, the physical design, energy band diagram, temperature dependent electrical resistivity and the impedance spectroscopy measurements of the Au/Bi2O3/ZnS/Ag isotype heterojunction devices are reported. The devices are prepared by the thermal evaporation technique under vacuum pressure of 10(-5) mbar. Structural, compositional and morphological studies has shown the presence of an expansion in the lattice of Bi2O3 associated with increased strain and dislocation density and decreased grain size as a result of ZnS interfacing. The design of the band diagram indicated that the formed heterojunction exhibit large valence and conduction band offsets that forces charge accumulation at the interface. The Au/Bi2O3/ZnS/Ag device displays negative capacitance (NC) effect in the frequency domain of 0.01-1.50 GHz. The NC effect is interrupted by a resonance-antiresonance phenomenon in the frequency domain of 0.90-1.07 GHz. In addition to the NC effects, the device under study exhibited reflection coefficient and return loss spectra that nominate it for use as microwave cavities or as low pass band filters.
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    Article
    Citation - WoS: 8
    Citation - Scopus: 8
    Effect of Lithium Nanosandwiching on the Structural, Optical and Dielectric Performance of Moo3
    (Elsevier, 2019) Al Garni, S. E.; Qasrawi, A. F.
    In this article, we discuss the effects of lithium nanosheets on the structural, optical, dielectric and optical conductivity parameters of the MoO3 films. The nanosandwiching of Li layers between two layers of MoO3 of thicknesses larger than 20 nm induced the crystallization process of the amorphous MoO3. Namely, MoO3 thin films that are nanosandwiched with Li sheets of thicknesses larger than 50 nm, exhibit structural phase transitions from hexagonal to monoclinic and reveals larger crystallite sizes. The possible formation of Li2O at the MoO3/Li/MoO3 interfaces is simulated and discussed. Optically, the Li nanosandwiching is observed to enhance the light absorbability by 11.0 times at 2.0 eV and successfully engineered the energy bands gap in the range of 3.05-0.45 eV. It also enhances the dielectric performance. In addition, relatively thick layers of lithium (200 nm) succeeds in converting the conductivity type from n-to p-type. The modeling of the dielectric spectra in accordance with the Drude- Lorentz approach have shown that the presence of Li in the structure of MoO(3 )significantly increases the drift mobility values of electrons from 5.86 to 11.40 cm(2)/V. The plasmon frequency range for this system varies in the frequency domain of 0.32-5.94 GHz. The features of MoO3/Li/MoO3 interfaces make them attractive for thin film transistor technology as optical receivers being promising for use in optical communications.
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    Article
    Citation - Scopus: 1
    Structural and Electrical Performance of Moo3 Films Designed as Microwave Resonators
    (inst Materials Physics, 2020) Al Garni, S. E.; Qasrawi, A. F.; Alharbi, S. R.; Department of Electrical & Electronics Engineering
    In this work, the effect of the insertion of lithium slabs of thicknesses of 50 nm between stacked layers of MoO3 is considered. Stacked layers of MoO3 comprising lithium slabs are prepared by the thermal evaporation technique onto Au substrates under vacuum pressure of 10(-5) mbar. The effects of Li slabs are explored by the X-ray diffraction, scanning electron microscopy, current-voltage characteristics and impedance spectroscopy techniques in the frequency domain of 0.01-1.80 GHz. While the presence of Li slabs did not alter the amorphous nature of structure, it forced the growth of rod-like grains of diameters of 100-160 nm and lengths of 1.5 mu m. Electrically, the presence of Li in the samples enhanced the rectifying properties of the devices and force reverse to forward current ratios larger than 60 times. Li slabs also controlled the negative capacitance effect and resonance -antiresonance regions in the Au/MoO3/MoO3/C stacked layers. While the Au/MoO3/MoO3/C devices displayed high conductance and low impedance values in the studied frequency domain, the Au/MoO3/Li/MOO3/C devices exhibited low conductance and high impedance mode in the frequency domain of 0.01-0.59 GHz. It is also found that the presence of Li slabs improved the performance of the devices through driving it to exhibit lower reflection coefficient and high return loss values near 0.80 GHz. The features of the devices nominate them for use as RF-Microwave traps or resonators.