Browsing by Author "Omar, Ahmad"
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Article Citation Count: 2Enhancement of Nonlinear Optical and Dielectric Properties of Cu2O Films Sandwiched with Indium Slabs(Wiley-v C H verlag Gmbh, 2020) Qasrawı, Atef Fayez Hasan; Qasrawi, Atef F.; Department of Electrical & Electronics EngineeringIn this work, the effects of the insertion of indium slabs of thickness 100 nm on the performance of stacked layers of Cu2O are reported. Cu2O/In/Cu2O thin films coated onto ultrasonically cleaned glass substrates are structurally, morphologically, optically, and dielectrically studied. The glassy films of Cu2O display larger, well-ordered grains in an amorphous sea of Cu2O upon insertion of indium slabs between layers of Cu2O. Optically, the indium slabs increase the light absorbability in the IR region by 12.5 times, narrow the energy bandgap, and widen the energy band tails region. They also enhance the nonlinearity in the dielectric response and increase the dielectric constant values by 2.5 times. In addition, the optical conductivity parameters are obtained from the fittings of the dielectric spectra. The analyses reveal an enhancement in the drift mobility, plasmon frequency, and free carrier density via stacking of the indium layer between layers of Cu2O. The drift mobility and plasmon frequency values reach 232.4 cm(2) V-1 s(-1) and 3.95 GHz at a reduced hole-plasmon frequency value of 6.0 x 10(14) Hz (2.48 eV). The values are promising as they indicate the applicability of Cu2O/In/Cu2O interfaces in optoelectronics as thin film transistors and electromagnetic wave cavities.Article Citation Count: 1p-TlGaSeS/n-BN heterojunction as a microwave filter and as a photovoltaic device(Wiley-v C H verlag Gmbh, 2015) Qasrawı, Atef Fayez Hasan; Omar, Ahmad; Azamtta, Ala' M.; Gasanly, Nizami M.; Department of Electrical & Electronics EngineeringIn this work, a p-n junction made of p-type TlGaSeS and n-type boron nitride (BN) is investigated and characterized. The bilayer was studied by means of capacitance-voltage characteristics, current-voltage characteristics and Bode signal and photovoltaic effect diagnostics. It was observed that the pTlGaSeS/n-BN bilayer exhibits negative capacitance values in the frequency range of 30-80 MHz. For an ac signal of 30 MHz, the built-in voltage and density of noncompensating carriers for the device are found to 1.06 eV and 1.72 x 10(12) cm(-3), respectively. The characteristic Bode curve analysis indicated that the bilayer behaves as a lowpass microwave filter that blocks all signals of frequencies larger than 1.28 GHz. The time constant for this device is 124 ps. In addition, the p-TlGaSeS/n-BN junction exhibited a well-pronounced photovoltaic effect. The device showed switching properties from low to high-current injection at a particular switching voltage. The switching voltage is sensitive to the light energy and intensity. It decreased systematically with increasing light intensity and energy. The device responsivity is similar to 7.64mAW(-1). The filtering and photovoltaic properties of the device suggest its use as an optoelectronic switch and as a microwave filter being suitable for multipurpose operations. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim