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Article Citation - WoS: 9Citation - Scopus: 8Exploring the Optical Dynamics in the Ito/As2< Interfaces(Springer, 2019) Al Garni, S. E.; Qasrawi, A. F.In this work, the effects of indium tin oxide (ITO) substrates on the structural, compositional, optical dielectric and optical conduction properties of arsenic selenide thin films are investigated. The As2Se3 films which are prepared by the thermal deposition technique under vacuum pressure of 10(-5) mbar exhibit an induced crystallization process, improved stoichiometry, increased optical transmittance in the visible range of light and increased dielectric response in the infrared range of light upon replacement of glass substrates by ITO. The ITO/As2Se3 interfaces exhibit conduction and valence band offset values of 0.46 eV and 0.91 eV, respectively. The experimental optical conductivity spectra are theoretically reproduced with the help of the Drude-Lorentz approach for optical conduction. In accordance with this approach, owing to the improved crystallinity of the arsenic selenide, the deposition of As2Se3 onto ITO substrates increases the drift mobility value from similar to 17.6 cm(2)/Vs to 34.6 cm(2)/Vs. It also reduces the density of free carriers by one order of magnitude. The ITO/As2Se3/C heterojunction devices which are tested as band filters which may operate in the frequency domain of 0.01-3.0 GHz revealed low pass filter characteristics below 0.35 GHz and band pass filter characteristics in the remaining spectral range.Article Citation - WoS: 16Citation - Scopus: 15Design and Characterization of the Ge/Ga2< Heterojunction(Springer, 2017) Al Garni, S. E.; Qasrawi, A. F.In this work, the formation and properties of Ga2S3 thin films deposited onto polycrystalline Ge substrates are studied by means of scanning electron microscopy, energy dispersive x-ray analyzer, Raman spectroscopy, x-ray diffraction techniques, ultraviolet-visible light spectrophotometry in the range of 300-1100 nm and by ac signal power spectroscopy in the range of 0.2-3.0 GHz. The first four techniques allowed the determining of the stoichiometry, the vibrational frequencies, the lattice parameters, the plane orientations, the strain and the defect density for the interface. In addition, it was observed that the Ge/Ga2S3 interface exhibited conduction and valence band offsets of 0.83 eV and 0.82 eV, respectively, and the real part of the dielectric spectra experimentally exhibited four resonance peaks centered at frequencies above 357 THz. Moreover, the computational analysis of the imaginary part of the dielectric constant via the Drude-Lorentz model has shown that the interface wave filtering properties are controlled by the electron-plasmon coupling with plasma frequencies in the range of 1.33-2.30 GHz. The drift mobility of electrons in this range was found to be 15.61 cm(2)/Vs. The real ability of the interface to control wave propagation was confirmed with ac signals propagating tests. The plasmonic features of the interface nominate it for use in microwave cavities and as wireless terahertz receivers.Article Citation - WoS: 9Citation - Scopus: 8Plasmon Interactions at the (ag, Al)/Inse Thin-Film Interfaces Designed for Dual Terahertz/Gigahertz Applications(Springer, 2017) Al Garni, S. E.; Omar, A.; Qasrawi, A. F.In this article, we investigate the plasmon-dielectric spectral interaction in the Ag/InSe and Al/InSe thin-film interfaces. The mechanism is explored by means of optical absorbance and reflectance at terahertz frequencies and by the impedance spectroscopy at gigahertz frequencies. It was observed that the interfacing of the InSe with Ag and Al metals with a film thickness of 250 nm causes an energy band gap shift that suits the production of thin-film optoelectronic devices. The reflectance and dielectric constant and optical conductivity spectral analysis of these devices displayed the properties of wireless band stop filters at 390 THz. The physical parameters which are computed from the conductivity spectra revealed higher mobility of charge carriers at the Al/InSe interface over that of Ag/InSe. The respective electron-bounded plasmon frequencies are found to be 2.61 and 2.13 GHz. On the other hand, the impedance spectral analysis displayed a microwave resonator feature with series resonance peak position at 1.68 GHz for the Al/InSe/Ag interface. In addition, the temperature-dependent impedance spectra, which were recorded in the temperature range of 300-420 K, revealed no significant effect of temperature on the wave trapping properties of the Al/InSe/Ag interface. The sensitivity of the interfaces to terahertz and gigahertz frequencies nominates it as laser light/microwave traps, which are used in fibers and communications.
