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Author: Qasrawi, Atef FayezSubject: tunneling diodes

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    Article
    Citation - WoS: 6
    Citation - Scopus: 5
    Characterization of Au/As2< Multifunctional Tunneling Devices
    (Wiley-v C H verlag Gmbh, 2020) Qasrawi, Atef Fayez
    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.
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    Article
    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
    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.