Browsing by Author "AlGarni, Sabah E."

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Citation - WoS: 9
Citation - Scopus: 9
Indium Slabs Induced Structural Phase Transitions and Their Effects on the Electrical and Optical Properties of Stacked Layers of the Thermally Annealed Cu₂o Thin Films
(Elsevier, 2020) AlGarni, Sabah E.; Qasrawi, A. F.
In this work, the effects of the structural evolutions caused by the insertion of indium slabs (100 nm) between layers of cupric oxide on the electrical and optical properties are investigated. The stacked layers of Cu2O/Cu2O (CC) which are thermally annealed at 500 degrees C in a vacuum media is observed to comprise both of the CuO (45.9%) and Cu2O (54.1%) phases in its structure. The major structural phase of CuO and Cu2O are monoclinic and orthorhombic, respectively. Insertion of indium slabs which is followed by thermal annealing reduced the content of CuO to 29.2% and enriched the content of Cu2O to 70.8%. The CC samples exhibited structural phase transitions from monoclinic CuO to hexagonal Cu2O in the presence of indium and under thermal annealing. The insertion of indium slabs in the samples increased the crystallite size and enhanced the optical transmittance. It also decreased the microstrain, the defect density and the electrical resistivity. The donor states are shifted deeper below the conduction band edge. The nature of optical transitions also changed from direct allowed to direct forbidden with a decrease in the energy band gap values from 2.05 to 0.85 eV upon indium slabs insertion followed by annealing process.
Citation - WoS: 7
Citation - Scopus: 8
Nonlinear Optical Performance of Cdo/Inse Interfaces
(Iop Publishing Ltd, 2020) AlGarni, Sabah E.; Qasrawi, A. F.
In this article, the growth nature, structural and optical properties of CdO/InSe interfaces are investigated. The CdO/InSe interfaces are prepared by the thermal vacuum deposition technique. Structurally, while the CdO exhibited cubic structure, the InSe layer was amorphous in nature. The morphological analyses have shown that the interface is composed of randomly distributed circular grains of average sizes of similar to 170 nm. The interfacing of the CdO and InSe resulted in enhancing the light absorbability of CdO by similar to 21 times in the IR range. It also showed well aligned conduction bands and valence band offset of 0.72 eV. The Drude-Lorentz modeling of the imaginary part of the dielectric spectra of the CdO/InSe interfaces has shown that the device is suitable for the fabrication of field effect transistors. The drift mobility of free carriers at the interface reached 42.27 cm(2)/Vs. In addition, a quality factor larger than 10(3) is achieved in the IR range indicating the suitability of these optical interfaces to store electromagnetic energy. These properties are important as they shows the applicability of the CdO/InSe interface in solar cells and optoelectronics as optical signal receivers or converters.
Citation - WoS: 3
Citation - Scopus: 4
Preparation and Characterization of Cdo/In_{6< Thin Film Transistors}
(Univ Fed Sao Carlos, dept Engenharia Materials, 2020) AlGarni, Sabah E.; Qasrawi, A. F.
In this study, the design and characterization of CdO/InSe thin film transistors (TFT) that are grown onto Au substrates are investigated. The devices are also subjected to a vacuum annealing process at 300 degrees C to enhance the structure and electrical performance. It was observed that the growth of polycrystalline monoclinic In6Se7 phase of InSe is preferred at this annealing temperature when coated onto Au/CdO substrates. Electrically, noisy negative capacitance effect accompanied with resonance-antiresonance phenomena is observed in the capacitance spectra of the as prepared TFT devices. The annealing of the TFT devices reduced the noise in the capacitance, conductance, impedance, and reflection coefficient and return loss spectral responses. The heat treated TFT devices displayed low bandpass, high bandpass and bandstop filter characteristics in the studied frequency domain (0.01-1.80 GHz) indicating the applicability of these devices as radio wave-microwave resonators.
Citation - WoS: 9
Citation - Scopus: 9
Yb/Inse Straddling-Type Tunneling Devices Designed as Photosensors, Mos Capacitors, and Gigahertz Bandstop Filters
(Ieee-inst Electrical Electronics Engineers inc, 2021) Alfhaid, Latifah Hamad Khalid; Qasrawı, Atef Fayez Hasan; Qasrawi, A. F.; AlGarni, Sabah E.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics Engineering
In this work, amorphous InSe thin films coated with 30-160-nm-thick SiO2 are used as an active material to fabricate multifunctional devices. The n-InSe/p-SiO2 layers that are deposited onto ytterbium substrates are optically and electrically characterized. It was observed that the coating of SiO2 nanosheets onto the surface of InSe enhances the light absorbability in the near-infrared range without remarkable altering of the bandgap. Significant increase in the steady-state photocurrent values accompanied by faster photocurrent responses resulted from the coating of SiO2 nanosheets. Electrically, while the Yb/InSe/Au channels display tunneling Schottky barrier characteristics, the Yb/InSe/SiO2/Au channels show pn junction features. Both channels displayed metal-oxide-semiconductors (MOS) capacitance-voltage characteristics. In addition, the analyses of the current-voltage characteristics have shown that the currents in the Yb/InSe/Au and Yb/InSe/SiO2 (30 nm)/Au channel are dominated by electric field-assisted thermionic emission (tunneling) of charge carriers through barriers of widths of 18/14 and 30/16 nm under reverse-/forward-biasing conditions, respectively. Further increase in the oxide layer thickness lowered the barrier height of the devices. On the other hand, when an ac signal of low amplitude is imposed through the device channels, the conductance, capacitance, and reflection coefficient spectra displayed bandstop filter characteristics near 1.6 GHz. The microwave cutoff frequency spectra show a remarkable increase in the cutoff frequency values as a result of the coating of InSe with SiO2 nanosheets. The features of the device assure its applicability as rectifying diodes, fast photosensors, MOS capacitors, and microwave bandstop filters.