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Article Citation - WoS: 2Citation - Scopus: 2Effects of Laser Excitation and Temperature on Ag/Gase0.5< Microwave Filters(Springer, 2014) Qasrawi, A. F.; Khanfar, H. K.The effects of temperature, illumination, and microwave signals on Ag/GaS0.5S0.5/C Schottky-type microwave filters have been investigated. The devices, which were produced from thin layers of GaSe0.5S0.5 single crystal, had room temperature barrier height and ideality factor of 0.65 eV and 3.28, respectively. Barrier height increased uniformly with increasing temperature, at 2.12 x 10(-2) eV/K, and the ideality factor approached ideality. The devices can even function at 95A degrees C. A current switching phenomenon from low to high injection ("On/Off") was also observed; this current switching appears at a particular voltage, V (s), that shifts toward lower values as the temperature is increased. When the devices were reverse-biased and illuminated with a laser beam of wavelength 406 nm, a readily distinguishable V (s) was observed that shifted with increasing laser power. When the devices were run in passive mode and excited with an ac signal of power 0.0-20.0 dBm and frequency 0.05-3.0 GHz they behaved as band filters that reject signals at 1.69 GHz. Device resistance was more sensitive to signal amplitude at low frequencies (50 MHz) than at high frequencies. The features of these Ag/GaS0.5S0.5/C Schottky devices imply that they may be used as optical switches, as self standing, low band-pass, band reject filters, and as high band-pass microwave filters.Article Citation - WoS: 7Citation - Scopus: 7Physical Design and Dynamical Analysis of Resonant-Antiresonant Ag/MgO/GaSe/Al Optoelectronic Microwave Devices(Springer, 2015) Kmail, Renal R. N.; Qasrawi, A. F.In this work, the design and optical and electrical properties of MgO/GaSe heterojunction devices are reported and discussed. The device was designed using 0.4-mu m-thick n-type GaSe as substrate for a 1.6-mu m-thick p-type MgO optoelectronic window. The device was characterized by means of ultraviolet-visible optical spectrophotometry in the wavelength region from 200 nm to 1100 nm, current-voltage (I-V) characteristics, impedance spectroscopy in the range from 1.0 MHz to 1.8 GHz, and microwave amplitude spectroscopy in the frequency range from 1.0 MHz to 3.0 GHz. Optical analysis of the MgO/GaSe heterojunction revealed enhanced absorbing ability of the GaSe below 2.90 eV with an energy bandgap shift from 2.10 eV for the GaSe substrate to 1.90 eV for the heterojunction design. On the other hand, analysis of I-V characteristics revealed a tunneling-type device conducting current by electric field-assisted tunneling of charged particles through a barrier with height of 0.81 eV and depletion region width of 670 nm and 116 nm when forward and reverse biased, respectively. Very interesting features of the device are observed when subjected to alternating current (ac) signal analysis. In particular, the device exhibited resonance-antiresonance behavior and negative capacitance characteristics near 1.0 GHz. The device quality factor was similar to 10(2). In addition, when a small ac signal of Bluetooth amplitude (0.0 dBm) was imposed between the device terminals, the power spectra of the device displayed tunable band-stop filter characteristics with maximum notch frequency of 1.6 GHz. The energy bandgap discontinuity, the resonance-antiresonance behavior, the negative capacitance features, and the tunability of the electromagnetic power spectra at microwave frequencies nominate the Ag/MgO/GaSe/Al device as a promising optoelectronic device for use in multipurpose operations at microwave frequencies.Article Citation - WoS: 11Citation - Scopus: 11Design and Applications of Al/Inse Hybrid Device(Ieee-inst Electrical Electronics Engineers inc, 2015) Qasrawi, Atef F.; Khanfar, Hazem K.In this paper, a hybrid device made of Ag/BN Schottky barrier and anisotype InSe/BN heterojunction is designed and characterized. The design of the energy band diagram of the device revealed a valance band splitting at the InSe/BN interface and a barrier height at the Ag/BN junction of 3.04 and 6.49 eV, respectively. These parameters which were designed to force current conduction by tunneling were experimentally confirmed by the dark I-V characteristics which revealed an electric field assisted tunneling process. The hybrid device exhibited high/low current switching property at Vs = 2.60 V when forward biased. When the device was exposed to 850-nm lasers light, Vs regularly increased with increasing light power indicating the applicability of these devices as IR photodetectors. In addition, when it was used as capacitor and depleted with signal of frequency of 0.1 GHz and varying amplitude it showed good energy storing property with a quality factor of similar to 200. On the other hand, when the hybrid device was used as microwave resonator it behaves like bandstop filter that blocks signals of various notch frequencies in the range of 1.58-2.30 GHz. The features of the device are promising as they indicate the applicability of the Al/InSe/BN/Ag in communication technology.Article Citation - WoS: 4Citation - Scopus: 5Znse/Al Nanosandwiched Structures as Dual Terahertz-Gigahertz Signal Receivers(Iop Publishing Ltd, 2019) Qasrawi, A. F.; Alsabe, Ansam M.In the current work, we focus on the enhancements in performance of the ZnSe terahertz/gigahertz signal receivers which are achieved by the insertion of nanosheets of Al layers of thickness of 30 nm between two 500 nm thick layers of ZnSe. The Al nanosandwiching which decreased the defect density, stacking faults and increased the grain size in the films increased the optical conductivity by more than 125%, increased the drift mobility to 313 cm(2) V-1 s(-1) and widens the plasmon frequency ranges to 0.49-4.92 GHz. In addition, the analysis of the terahertz cutoff (f(co)) frequency spectra have shown that the presence of Al nanosheets improves the cutoff frequency value by three orders of magnitude making the ZnSe receivers more suitable for visible light and IR communication technology. The value of f(co) is 49.6 THz when light signal of wavelengths of 408 nm that suits blue lasers is irradiated. Moreover, the impedance spectroscopy analysis in the gigahertz frequency domain has shown that the Al sandwiched ZnSe exhibits negative capacitance spectra in the frequency domain of 0.01-1.04 GHz. This property is useful for parasitic capacitance cancelling and noise reducing in circuits. Furthermore, the study of the microwave cutoff frequency spectra has shown that the value of f(co) is enhanced by three orders of magnitude above 1.5 GHz.Article Citation - WoS: 2Citation - Scopus: 2Mgo/Gase0.5< Heterojunction as Photodiodes and Microwave Resonators(Ieee-inst Electrical Electronics Engineers inc, 2016) Qasrawi, Atef F.; Khanfar, Hazem K.; Gasanly, N. M.In this paper, a multifunctional operating optoelectronic device that suits visible light (VLC) and microwave communication systems is designed and characterized. The device which is composed of p-type MgO and n-type GaSe0.5S0.5 heterojunction is characterized by means of optical absorbance in the incident light energy (E) region of 3.5-1.1 eV, dark and illuminated current (I)-voltage (V) characteristics, and impedance spectra in the frequency range of 1M-1.8 GHz. Four types of lasers which generate light of wavelengths 406, 632, 850, and 1550 nm are used to excite the active region of the device. The device was also illuminated by non-monochromatic light. The incident light power was varied in the range of 1.12-10.17 mu W. It was observed that the heterojunction exhibits an optical energy bandgap (E-g) of 1.85 eV. For laser excitation with E > Eg, the photosensitivity (S) exceeds 67 while it is less than unity for excitations with E < Eg. These behaviors are assigned to the intrinsic and extrinsic nature of absorption, respectively. In addition, S increases as a result of energy barrier height lowering with increasing light power. On the other hand, when the device was excited with ac signal, the capacitance and impedance of the device displayed a resonance-antiresonance property associated with negative differential resistance and very high signal quality factor (10(3)) above 1.37 GHz. The bandwidth of the two resonance-antiresonance peaks is 319 and 12.6 MHz at 1.475 and 1.649 GHz, respectively. These results are attractive for using the heterojunction in VLC and microwave communication technologies.
