Browsing by Author "Alharbi, Seham Reef"

Now showing 1 - 4 of 4

Citation Count: 2
Characterization of the Ge/Bi_{2< Interfaces}
(Univ Fed Sao Carlos, dept Engenharia Materials, 2019) Alharbi, Seham Reef; Qasrawı, Atef Fayez Hasan; 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 Count: 23
Effects of Au Nanoslabs on the Performance of Cdo Thin Films Designed for Optoelectronic Applications
(Elsevier, 2021) Alharbi, Seham Reef; Qasrawı, Atef Fayez Hasan; Qasrawi, A. F.; Department of Electrical & Electronics Engineering
In this work, the effect of 50 nm thick gold nanosheets on the structural, morphological, optical and electrical properties of stacked layers of CdO are investigated. The insertion of Au nanoslabs decreased the lattice parameters of the cubic unit cells of CdO. It also decreased the microstrain, the defect density, the stacking fault percentage and increased the crystallite and grain sizes. Optically, the light absorbability is enhanced, the energy band gap is shrunk and the optical conductivity is increased. The optical conductivity parameters presented by scattering time, plasmon frequency, drift mobility and free carrier density are all engineered via participation of Au nanosheets. On the other hand, electrical measurements in the frequency domain of 0.01-1.80 GHz indicated that the Au nanosheets forced the capacitance spectra to exhibit negative values and increased the electrical conductivity in the studied frequency domain. The terahertz cutoff frequency is tuned in the range of 5.0-22.0 THz indicating the applicability of the CdO/Au/CdO (CAC) films as terahertz filters. The direct current electrical conductivity measurements have shown that while the CC samples exhibit nondegenerate extrinsic nature of conduction, the CAC samples displayed degenerate/nondegenerate transitions at 400 K. With the feature of negative capacitance that can be used for noise reduction and parasitic capacitance cancellation, the CAC films can be regarded as promising structure for multifunctional device applications.
Citation Count: 7
Enhancing the Optoelectronic Performance of As₂se_{3< Thin Films Via Ag Slabs Sandwiching}
(Elsevier Gmbh, 2020) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Alharbi, Seham Reef; Department of Electrical & Electronics Engineering
In this work, the effects of insertion of Ag slabs of thicknesses of 50, 100 and 200 nm between layers of arsenic selenide are reported. The glassy structured As2Se3 is characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, ultraviolet-visible light spectrophotometry and impedance spectroscopy techniques. While the two stacked layers of As2Se3 exhibited high absorption and energy band gap values that nominate them for optoelectronic applications, the Ag slabs enhanced the light absorbability by 3.98, 5.77, 6.13 times and shrunk the energy band gap by 1.16 %, 7.40 % and 13.8 % for Ag slabs of thicknesses of 50, 100 and 200 nm, respectively. In addition, even though the As2Se3/As2Se3 layers exhibited negative capacitance effect in the frequency domain of 0.01-1.80 GHz, the insertion of Ag slabs removed the negative capacitance effect and forced the capacitance spectra to exhibit resonance at critical frequency of value of 0.23 GHz. The modeling of the capacitance spectra have shown that the geometrical capacitance is increased by one order of magnitude upon Ag slabs insertion. The dynamic capacitance is limited by electrons (holes) plasmonic interaction at the interface between the As2Se3/Ag/As2Se3 layers. Furthermore, the capacitance- voltage characteristics of the As2Se3/Ag/As2Se3 films confirmed the suitability of the devices to exhibit MOS device features. The characteristics of the stacked layers of As2Se3 indicate their multi-functionality as an optical absorbers/receivers and as microwave cavities.
Citation Count: 10
Structural and Optoelectronic Properties of Moo₃ Interfaces
(Wiley-v C H verlag Gmbh, 2019) Alharbi, Seham Reef; Qasrawı, Atef Fayez Hasan; 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.