Browsing by Author "Omar, A."

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Citation - WoS: 10
Citation - Scopus: 10
Effects of Indium Slabs on the Structural and Electrical Properties of Stacked Layers of Cu₂o
(Natl inst R&d Materials Physics, 2020) Qasrawi, A. F.; Omar, A.; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
In this work, the structural and electrical properties of stacked layers of Cu2O that comprises indium slabs in its structure are reported. The stacked layers which are coated onto glass and Au substrates under vacuum pressure of 10(-5) mbar are characterized by the X-ray diffraction and impedance spectrometry techniques. While the Cu2O/Cu2O (CC) layers exhibited amorphous nature of growth, those which contained indium slabs (CIC) displayed weak crystallinity The insertion of indium slabs between stacked layers of cuprous oxide highly increased the electrical resistivity and shifted the acceptor level closer to the valance band edge. In addition, the analyses of the conductance and capacitance spectra in the frequency domain of 0.01-1.0 GHz have shown that these two physical parameters are strongly affected by the insertion of indium slabs and by surface deformation effects. The capacitance spectra showed negative capacitance effect (NC) in all the studied frequency domain The NC effects become less pronounced in the CIC samples owing to the changes in the polarization mechanism. The feature of NC effects make both of the CC and CIC samples more appropriate for electronic and telecommunication technology as it can be used in amplifiers to enhance he gain, as parasitic cancellers and as noise reducers.
Citation - WoS: 9
Citation - Scopus: 8
Plasmon Interactions at the (ag, Al)/Inse Thin-Film Interfaces Designed for Dual Terahertz/Gigahertz Applications
(Springer, 2017) Al Garni, S. E.; Omar, A.; Qasrawi, A. F.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
In this article, we investigate the plasmon-dielectric spectral interaction in the Ag/InSe and Al/InSe thin-film interfaces. The mechanism is explored by means of optical absorbance and reflectance at terahertz frequencies and by the impedance spectroscopy at gigahertz frequencies. It was observed that the interfacing of the InSe with Ag and Al metals with a film thickness of 250 nm causes an energy band gap shift that suits the production of thin-film optoelectronic devices. The reflectance and dielectric constant and optical conductivity spectral analysis of these devices displayed the properties of wireless band stop filters at 390 THz. The physical parameters which are computed from the conductivity spectra revealed higher mobility of charge carriers at the Al/InSe interface over that of Ag/InSe. The respective electron-bounded plasmon frequencies are found to be 2.61 and 2.13 GHz. On the other hand, the impedance spectral analysis displayed a microwave resonator feature with series resonance peak position at 1.68 GHz for the Al/InSe/Ag interface. In addition, the temperature-dependent impedance spectra, which were recorded in the temperature range of 300-420 K, revealed no significant effect of temperature on the wave trapping properties of the Al/InSe/Ag interface. The sensitivity of the interfaces to terahertz and gigahertz frequencies nominates it as laser light/microwave traps, which are used in fibers and communications.
Citation - WoS: 22
Citation - Scopus: 23
Temperature Effects on the Structural and Optical Properties of the Tlinse_2xs_{2(1-x)< Mixed Crystals (x=0.3)}
(Elsevier Science Sa, 2017) Omar, A.; Qasrawi, A. F.; Gasanly, N. M.; Department of Electrical & Electronics Engineering; 15. Graduate School of Natural and Applied Sciences; 01. Atılım University
In this work, we have studied the temperature effects on the recrystallization process and on the energy band gap of the TlInSe(2)xS(2(1 - x)) mixed crystals at the critical composition (x = 0.3) where structural phase transition from tetragonal to monoclinic takes place. Remarkable effect which included permanent recrystallization process, enlargements in the monoclinic crystallite size, decreases in the compressing strain and in the dislocation density as well as in the stacking faults and in the energy band gap with increasing temperature were observed. In addition, the temperature dependent energy band gap of the crystal which is investigated in the same temperature range that was used for the recrystallization process revealed that the recrystallization process is associated with energy band gap narrowing. (C) 2017 Elsevier B.V. All rights reserved.