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Article Citation - WoS: 12Citation - Scopus: 13Performance of the Au/Mgo Photovoltaic Devices(Elsevier Sci Ltd, 2015) 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: 3Citation - Scopus: 3Current Transport Mechanism in Au-p-mgo-ni Schottky Device Designed for Microwave Sensing(Natl inst Optoelectronics, 2016) Qasrawi, A. F.; Khanfar, H. K.; Department of Electrical & Electronics EngineeringAu/MgO/Ni back to back Schottky tunnelling barriers are designed on the surface of an MgO thin layer and are electrically characterized. The current voltage curve analysis has shown that thermionic emission, field effect thermionic (FET) emission and space charge limited current are dominant transport mechanism in distinct biasing regions. It was shown that, while the device is reverse biased with voltages less than 0.31 V, it conducts by tunnelling (FED though an energy barrier of 0.88 eV with a depletion region width of 15.7 nm. As the voltage exceeds 0.46 V, the tunnelling energy barrier is lowered to 0.76 eV and the depletion region widens and arrives at the reach-through running mode. The device was tested in the microwave electromagnetic power range that extends from Bluetooth to WLAN radiation levels at oscillating frequencies of 0.5 and 2.9 GHz. In addition, a low power resonating signal that suits mobile data is superimposed in the device. It was observed that the Au/MgO/Au sensors exhibit a wide tunability range via voltage biasing or via frequency control. The signal quality factor is 3.53 x 10(3) at 2.9 GHz. These properties reflect applicability in microwave technology as wireless and connectorized microwave amplifiers, microwave resonators and mixers.Article Citation - WoS: 4Citation - Scopus: 4Optical Characterization of the Mgo/Inse Interface(Wiley-v C H verlag Gmbh, 2015) Kayed, T. S.; Qasrawi, A. F.; Elsayed, Khaled A.In this work, a 500nm thick MgO layer deposited on the physically evaporated amorphous InSe thin film substrate is designed as a window for the MgO/InSe terahertz resonators. The optical properties including the reflectance and the dielectric constant dependence on the angle of incidence ((i)), the normal transmittance, and the absorption coefficient of the interface were investigated in the range of approximate to 270-1000THz. It was observed that the total reflectivity of the substrate continuously decreases with increasing (i) in the range of 33-80 degrees. The spectra of InSe and MgO/InSe revealed strong dielectric resonance patterns below 450THz. The energy bands of the direct allowed transitions in InSe film shrunk from 3.90, 2.75, and 1.49eV to 3.71, 2.10, and 0.96eV when MgO was deposited onto the InSe film. By analyzing the dielectric spectra, we were able to determine the static and lattice dielectric constants in addition to the oscillator and dispersion energies. The latter energy increased from 27.43 to 35.84 via interface construction.Article Citation - WoS: 12Citation - Scopus: 13Trap Characterization by Photo-Transferred Thermoluminescence in Mgo Nanoparticles(Elsevier, 2018) Isik, M.; Gasanly, N. M.Shallow trapping centers in MgO nanoparticles were characterized using photo-transferred thermoluminescence (TL) measurements. Experiments were carried out in low temperature range of 10-280 K with constant heating rate. Shallow traps were filled with charge carriers firstly by irradiating the sample at room temperature using S-90/Y-90 source and then illuminating at 10 K using blue LED. TL glow curve exhibited one peak around 150 K. Curve fitting analyses showed that this peak is composed of two individual peaks with maximum temperatures of 149.0 and 155.3 K. The activation energies of corresponding trapping centers were revealed as 0.70 and 0.91 eV. The dominant mechanism for TL process was found as second order kinetics which represent that fast retrapping is effective transitions taking place within the band gap. Structural characterization of MgO nanoparticles were investigated using x-ray diffraction, scanning electron microscopy and Fourier transform infrared spectroscopy measurements. Analyses of experimental observations indicated that MgO nanoparticles show good crystallinity with particle size in nanometer scale.Article Citation - WoS: 3Citation - Scopus: 3Investigations of 2.9-Ghz Resonant Microwave-Sensitive Ag/Mgo Tunneling Diodes(Springer, 2013) Qasrawi, A. F.; Khanfar, H. K.In this work, a resonant microwave-sensitive tunneling diode has been designed and investigated. The device, which is composed of a magnesium oxide (MgO) layer on an amorphous germanium (Ge) thin film, was characterized by means of temperature-dependent current (I)-voltage (V), room-temperature differential resistance (R)-voltage, and capacitance (C)-voltage characteristics. The device resonating signal was also tested and evaluated at 2.9 GHz. The I-V curves reflected weak temperature dependence and a wide tunneling region with peak-to-valley current ratio of similar to 1.1. The negative differential resistance region shifts toward lower biasing voltages as temperature increases. The true operational limit of the device was determined as 350 K. A novel response of the measured R-V and C-V to the incident alternating-current (ac) signal was observed at 300 K. Particularly, the response to a 100-MHz signal power ranging from the standard Bluetooth limit to the maximum output power of third-generation mobile phones reflects a wide range of tunability with discrete switching property at particular power limits. In addition, when the tunnel device was implanted as an amplifier for a 2.90-GHz resonating signal of the power of wireless local-area network (LAN) levels, signal gain of 80% with signal quality factor of 4.6 x 10(4) was registered. These remarkable properties make devices based on MgO-Ge interfaces suitable as electronic circuit elements for microwave applications, bias- and time-dependent electronic switches, and central processing unit (CPU) clocks.
