Browsing by Author "Qasrawi, Atef Fayez"

Now showing 1 - 6 of 6

Citation - WoS: 6
Citation - Scopus: 5
Characterization of Au/As_{2< Multifunctional Tunneling Devices}
(Wiley-v C H verlag Gmbh, 2020) Qasrawi, Atef Fayez; Department of Electrical & Electronics Engineering
Herein, the physical design and characterization of the Au/As2Se3 Schottky barrier that is prepared under a vacuum pressure of 10(-5) mbar are reported. The Schottky diodes are characterized by means of X-ray diffraction, energy-dispersive X-ray spectroscopy, current-voltage characteristics, and conductivity, capacitance, and impedance spectroscopy. It is observed that the Schottky barriers exhibit a biasing-dependent large rectification ratio with current conduction mechanisms dominated by the electric field-assisted quantum mechanical tunneling through a barrier height of 0.29 eV and depletion width of 13.3 nm. While the spectral analysis of the alternating current (AC) conductivity reveals mixed conduction with the contribution of both of the tunneling and correlated barriers hopping mechanisms, the capacitance spectra display resonance-antiresonance phenomena at 0.201 GHz. A wide range (0.21-1.80 GHz) of negative capacitance (NC) effects is observed in devices. In addition, the impedance spectroscopy analyses show that the Au/As2Se3 devices exhibit band-stop features with a notch frequency of 1.14 GHz and return loss value of 16 dB. The NC effect, resonance-antiresonance, filtering features, as well as the high rectification ratio at a relatively low biasing voltage (approximate to 0.30 V) nominate the Au/As2Se3 devices for applications which require noise reduction, parasitic effect cancellations, and microwave filtering.
Citation - WoS: 3
Citation - Scopus: 3
Characterization of the Ge/Bi_{2< Interfaces}
(Univ Fed Sao Carlos, dept Engenharia Materials, 2019) Alharbi, Seham Reef; Qasrawi, Atef Fayez; Department of Electrical & Electronics Engineering
In this article, the properties of the Ge/Bi2O3 interfaces as microwave cavities are reported and discussed. The interface is composed of monoclinic Bi2O3 films grown onto polycrystalline cubic Ge substrate. It is observed that consistent with the theoretical design of the energy band diagram, the experimental current-voltage characteristics of the Yb/Ge/Bi2O3/C hybrid device structure exhibits electronic switching property. In addition, the capacitance, resistance and microwave cutoff frequency spectral analysis in the frequency domain of 0.01-1.50 GHz revealed a frequency dependent tunability of the device. Moreover, while the Yb/Bi2O3/C interface displays negative capacitance effect, the Yb/Ge/Bi2O3/C interfaces are also found to have the ability of altering the resistance up to three orders of magnitude. Such property allowed reaching a cut off frequency up to 116 GHz. The electronic features of the device indicated that the Ge/Bi2O3 interfaces are attractive for production of negative capacitance field effect transistors and band pass/reject filters.
Citation - WoS: 6
Citation - Scopus: 6
Fabrication of (au, Mn)/Znpc Interfaces as Radiowave/Microwave Band Filters
(Wiley-v C H verlag Gmbh, 2020) Qasrawi, Atef Fayez; Zyoud, Hadeel Mohammad; Department of Electrical & Electronics Engineering
Herein, zinc phthalocyanine (ZnPc) layers are used as an active material to fabricated radiowave/microwave band filters. The thin layers of ZnPc are coated onto Au and Mn thin-film substrates to form ohmic and Schottky interfaces, respectively. The Au/ZnPc and Mn/ZnPc devices are structurally and electrically characterized by means of X-ray diffraction and impedance spectroscopy techniques in the frequency domain of 0.01-1.80 GHz, respectively. The structural investigations show that both interfaces exhibit strained structures of the monoclinic phase of ZnPc. It is also observed that while the Au/ZnPc/Ag devices display negative capacitance (NC) effects in the microwave region above 1.46 GHz, the Mn/ZnPc/Ag devices show resonance-antiresonance capacitive response in the radiowave region accompanied with NC effects in the range of 0.06-1.80 GHz. In addition, analyses of the reflection coefficient spectra have shown the ability of the (Mn, Au)/ZnPc/Ag interfaces to behave as a typical high-/low-bandpass filters. The filters can be operated in microwaves and radiowave ranges. The return loss spectral investigations on these filters have shown their ability to reach the market standards.
Citation - WoS: 3
Citation - Scopus: 3
Hot aluminum substrate induced hexagonal-tetragonal phase transitions in InSe and performance of Al/InSe/Cu₂O pn tunneling devices
(Wiley, 2020) Qasrawi, Atef Fayez; Kmail, Reham Reda; Department of Electrical & Electronics Engineering
In the current study, we have considered the induced phase transitions in Al/InSe thin film substrates and employing them for fabrication of InSe/Cu2O tunneling channels. The InSe substrates are observed to prefer the transition from the hexagonal gamma-In(2)Se(3)to the rarely observed tetragonal InSe. The phase transitions are obtained by the thermally assisted diffusion of aluminum, which was already kept at 250 degrees C in a vacuum media of 10(-5)mbar before the compensation of InSe. The tetragonal InSe also induced the crystallization of orthorhombic Cu2O with acceptable level of lattice matching along thea-axis. The Al/InSe/Cu2O/Au heterojunctions, which are electrically analyzed are observed to exhibit rectifying features with the current conduction being dominated by electric fields assisted thermionic emission (tunneling) through a barrier of width of 5.5 to 14.0 nm and barrier height of 0.19 to 0.30 eV. The ac analyses of the capacitance and conductance spectra of this device have shown that it can exhibit high/low capacitance and frequency dependent conductance switching modes at 0.12 GHz in addition to negative capacitance effect in the range of 0.12 to 1.80 GHz. The features of the device are promising as they indicate the suitability of the device for fabrication of field effect transistors, memory devices, and ultrafast switches.
Citation - WoS: 2
Citation - Scopus: 1
Hydrogen Implantation Effects on the Electrical and Optical Properties of Inse Thin Films
(Tubitak Scientific & Technological Research Council Turkey, 2012) Qasrawi, Atef Fayez; Ilaiwi, Khaled Faysal; Polimeni, Antonio; Department of Electrical & Electronics Engineering
The effects of hydrogen ion implantation on the structural, electrical and optical properties of amorphous InSe thin films have been investigated. X-ray diffraction analysis revealed no change in the structure of the films. An implantation of 7.3 x 10(18) ions/cm(2) decreased the electrical conductivity by three orders of magnitude at 300 K. Similarly, the conductivity activation energy, which was calculated in the temperature range of 300-420 K, decreased from 210 to 78 meV by H-ion implantation. The optical measurements showed that the direct allowed transitions energy band gap of amorphous InSe films has decreased from 1.50 to 0.97 eV by implantation. Furthermore, significant decreases in the dispersion and oscillator energy, static refractive index and static dielectric constants are also observed by hydrogen implantation.
Citation - WoS: 10
Citation - Scopus: 9
Structural and Optoelectronic Properties of Moo₃ Interfaces
(Wiley-v C H verlag Gmbh, 2019) Alharbi, Seham Reef; Qasrawi, Atef Fayez; Department of Electrical & Electronics Engineering
In this article, the authors discuss the growth nature, the structural, optical and dielectric properties of CuSe thin films deposited onto MoO3 substrate. The films are studied by the X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and ultraviolet-visible light spectroscopy techniques. CuSe thin films are observed to exhibit strained nature of growth when grown onto MoO3 amorphous substrates. Optically, the MoO3/CuSe films are found to exhibit conduction (Delta Ec) and valence (Delta Ev) band offsets of values of 3.70 and 3.42 eV, respectively. In addition, a remarkable increase in the absorbability (R lambda) of MoO3 by 72 times at 3.0 eV is obtained as a result of coating it with CuSe. The Delta Ec, Delta Ev, and R lambda values are significantly high and nominate the MoO3/CuSe interfaces for use in many optoelectronic applications. In addition, the dielectric analysis shows that the MoO3/CuSe heterojunction exhibit optical conductivity parameters that make it suitable for use in optical communications. Particularly, the Drude-Lorentz modeling of the imaginary part of the dielectric constant for the MoO3/CuSe interfaces displays mobility and plasmon frequency values of 7.76 cm(2) V-1 s(-1) and 3.78 GHz, respectively. The obtained plasmon frequency values indicate the applicability of this device in microwave technology.