Browsing by Author "Khanfar,H.K."

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Citation Count: 2
Current Transport Mechanism in Au-P Schottky Device Designed for Microwave Sensing
(National Institute of Optoelectronics, 2016) Qasrawi,A.F.; Qasrawı, Atef Fayez Hasan; Khanfar,H.K.; Department of Electrical & Electronics Engineering
Au/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 (FET) 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 ×103at 2.9 GHz. These properties reflect applicability in microwave technology as wireless and connectorized microwave amplifiers, microwave resonators and mixers. © 2016, National Institute of Optoelectronics. All rights reserved.
Citation Count: 2
Role of au nanosheets in enhancing the performance of yb/zns/cds/au tunneling photosensors
(S.C. Virtual Company of Phisics S.R.L, 2020) Qasrawı, Atef Fayez Hasan; Qasrawi,A.F.; Asaad,B.M.; Khanfar,H.K.; Department of Electrical & Electronics Engineering
In this study, the effects of Au nanosheets of thicknesses of 50 nm on the structural, electrical and photoelectrical properties of Yb/ZnS/CdS/Au (ZAC-0) devices is considered. Stacked layers of ZnS and CdS which are prepared by the thermal evaporation technique onto Yb substrates under vacuum pressure of 10-5 mbar exhibits rectifying characteristics. For these diodes a reverse to forward current ratios of ~105 at biasing voltage of 0.60 V is determined. Insertion of Au nanosheets between the stacked layers of ZnS and CdS increased the current values by three orders of magnitude and changed the current conduction mechanism from thermionic emission to tunneling under reverse biasing conditions. The ZAC-0 device, exhibit a barrier height lowering and barrier widening upon insertion of Au nanosheets. After the participation of Au nanosheets in the structure of the ZAC-0 devices, large photosensitivity and responsivity accompanied with high external quantum efficiency is observed. The responsivity to 406 nm laser radiation is biasing voltage dependent and reaches 135 mA/W at 0.60 V. The features of the Yb/ZnS/Au/CdS/Au photosensors nominate them as promising candidates for use in light communication technology as signal receivers. © 2020, S.C. Virtual Company of Phisics S.R.L. All rights reserved.
Citation Count: 1
Structural, Optical and Dielectric Performance of Molybdenum Trioxide Thin Films Sandwiched With Indium Sheets
(S.C. Virtual Company of Phisics S.R.L, 2020) Abusaa,M.; Qasrawı, Atef Fayez Hasan; Qasrawi,A.F.; Kmail,H.K.; Khanfar,H.K.; Department of Electrical & Electronics Engineering
In this work, we report the enhancements in the structural, optical and dielectric properties of molybdenum trioxide that are achieved by insertion of 50 and 100 nm thick indium sheets between layers of MoO3. The films which are coated onto ultrasonically glass substrates under a vacuum pressure of 10-5 mbar exhibited metal induced crystallization process upon insertion of indium sheets. Optically, indium sheets tuned the transmittance and reflectance, significantly, increased the absorption coefficient values and formed interbands in the band gap of MoO3. The energy band gap decreased with increasing indium sheets thickness. On the other hand, the insertion of indium layers into the structure of MoO3 is observed to improve the dielectric response of these films to values that nominate them for used in thin film transistor technology. In the same context, the analyses of the optical conductivity which are carried out with the help of Drude-Lorentz approach have shown that the presence of indium sheets can increase the optical conductivity and enhance the plasmon frequency and free charge carrier density of MoO3. The plasmon frequency is tuned in the range of 1.68-7.16 GHz making MoO3 films attractive for plasmonic applications. © 2020, S.C. Virtual Company of Phisics S.R.L. All rights reserved.