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Article Citation - WoS: 6Citation - Scopus: 6Design and characterization of (Al, C)/p-Ge/p-BN/C isotype resonant electronic devices(Wiley-v C H verlag Gmbh, 2015) Al Garni, S. E.; Qasrawi, A. F.In this work, a Ge/BN isotype electronic device that works as a selective microwave bandstop filter is designed and characterized. The interface is designed using a 50-m thick p-type BN on a 0.2-m thick p-type germanium thin film. The modeling of current-voltage characteristics of the Al/Ge/BN/C channel of the device revealed that the current is dominated by thermionic emission and by the tunneling of charged particles through energy barriers. The evaluation of the conduction parameters reflected a resonant circuit with a peak-to-valley current ratio of (PVCR) of 63 at a peak (V-p) and valley (V-v) voltages of 1.84 and 2.30V, respectively. The ac signal analysis of the Al/Ge/BN/C channel that was carried out in the frequency range of 1.0-3.0GHz displayed a bandstop filter properties with notch frequency (f(n)) of 2.04GHz and quality factor (Q) of 102. The replacement of the Al electrode by C through the C/Ge/BN/C channel caused the disappearance of the PVCR and shifted f(n) and Q to 2.70GHz and 100, respectively. The features of the Ge/BN device are promising as they indicate the applicability of these sensors in communication technology.Article Citation - WoS: 4Citation - Scopus: 4Characterization of Bi2o3< Heterojunctions Designed for Visible Light Communications(Iop Publishing Ltd, 2019) Al Garni, S. E.; Qasrawi, A. F.In the current work, the structural, morphological and optical properties of the Bi2O3/ZnS heterojunctions as visible light communication (VLC) technology element are explored. Bismuth oxide layers of thicknesses of 200 nm are used as substrate to evaporate ZnS films of thicknesses of 500 nm by the thermal evaporation technique under vacuum pressure of 10(-5) mbar. The heterojunction devices are studied by the x-ray diffraction, scanning electron microscopy, optical spectrophotometry and microwave spectroscopy techniques. The Bi2O3/ZnS heterojunctions are found to form a highly strained structure with extremely large lattice mismatches. By the strained structure and with the valence and conduction band offsets that exhibit values of 1.04 and 0.41 eV, respectively, it was possible to enhance the light absorbability of ZnS by 459 times at 3.10 eV. In addition, the dielectric constant spectra of the device display a linear and nonlinear optical properties below and above 1.94 eV, respectively. Moreover, the optical conductivity parameters including the drift mobility and plasmon frequency and the cutoff frequency spectra of an area of 0.50 cm(2) of Bi2O3/ZnS interfaces have shown the ability of using these heterojunction devices as light signal receivers that attenuate signals at terahertz frequencies in the range of 0.27-1.00 THz. As an additional demonstration, the Bi2O3/ZnS heterojunction devices were subjected to a microwave signal propagation in the frequency domain of 0.01-2.90 GHz. The device performed as band filters at gigahertz frequencies.Article Citation - WoS: 9Absorption and Optical Conduction in Inse/Znse Thin Film Transistors(World Scientific Publ Co Pte Ltd, 2016) Al Garni, S. E.; Qasrawi, A. F.In this work, (n)InSe/(p)ZnSe and (n)InSe/(p)ZnSe/(n)InSe heterojunction thin film transistor (TFT) devices are produced by the thermal evaporation technique. They are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy and optical spectroscopy techniques. While the InSe films are found to be amorphous, the ZnSe and InSe/ZnSe films exhibited polycrystalline nature of crystallization. The optical analysis has shown that these devices exhibit a conduction band offsets of 0.47 and valence band offsets of 0.67 and 0.74 eV, respectively. In addition, while the dielectric spectra of the InSe and ZnSe displayed resonance peaks at 416 and 528 THz, the dielectric spectra of InSe/ZnSe and InSe/ZnSe/InSe layers indicated two additional peaks at 305 and 350 THz, respectively. On the other hand, the optical conductivity analysis and modeling in the light of free carrier absorption theory reflected low values of drift mobilities associated with incident alternating electric fields at terahertz frequencies. The drift mobility of the charge carrier particles at femtoseconds scattering times increased as a result of the ZnSe sandwiching between two InSe layers. The valence band offsets, the dielectric resonance at 305 and 350 THz and the optical conductivity values nominate TFT devices for use in optoelectronics.Article Citation - WoS: 10Citation - Scopus: 9Tunable 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 EngineeringIn 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.Article Citation - WoS: 5Citation - Scopus: 5Formation 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 EngineeringIn 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.
