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Article Citation - WoS: 15Citation - Scopus: 16Electrical Parameters of Al/Inse Rf Sensors(Iop Publishing Ltd, 2014) Qasrawi, A. F.An Al/InSe/C Schottky device is designed on the surface of amorphous InSe thin films. The device is observed to exhibit a switching property at particular biasing voltages. The 'on/off' current ratio is found to be 7.9 and 9.3 at forward and reverse biasing voltages of 2.0 and 2.25 V, respectively. The 'off' and 'on' operational modes are ascribed to the domination of the tunneling of charged particles through a barrier height of 0.83 eV with a depletion region width of 64 nm and due to the domination of the thermionic emission of charged carriers over a barrier height of 0.53 eV, respectively. In addition, the spectral analysis of the capacitance of the device which was carried in the frequency range of 10.0 k-3.0 GHz reflected dc voltage biasing-dependent high quality resonating peaks. The strongest one appeared at a frequency of 36.8 MHz for a biasing voltage of 0.70 V. Furthermore, the loss tangent of the Al/InSe/C device is found to be of the order of 10(-7) at 3.0 GHz. Consistently, the capacitance-voltage spectra of these sensors reflected pronounced tunability up to 100 MHz. The Al/InSe/C device performance, the switching properties and the quality of the resonance peaks indicate the possibility of using these sensors in RF technology.Article Citation - WoS: 7Citation - Scopus: 7Plasmon-Electron Dynamics at the Au/Inse and Y/Inse Interfaces Designed as Dual Gigahertz-Terahertz Filters(Elsevier Gmbh, Urban & Fischer verlag, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the X-ray diffraction, the Scanning electron microscopy, the energy dispersive X-ray, the Raman, The UV-vis light and the impedance spectral techniques are employed to explore the structural, vibrational, optical and electrical properties of the Au/InSe and Y/InSe thin film interfaces. It was shown that with its amorphous nature of crystallization, the InSe thin films exhibited n-type conductivity due to the 3% excess selenium. For this form of InSe, the only active Raman spectral line is 121 (cm(-1)). In addition to the design of the energy band diagram, the analysis the dielectric spectra and the optical conductivities were possible in the frequency range of 270-1000 THz. The modeling of the optical conductivities of the Au, Y, Au/InSe and Y/InSe with the help of Lorentz approach for optical conduction, assured that the conduction is dominated by the resonant plasmon-electron interactions at the metals and metals/semiconductors interfaces. It also allowed tabulating the necessary parameters for possible applications in terahertz technology: These parameters are the electron effective masses, the free electron densities, the electron bounded plasmon frequencies, the electron scattering times, the reduced resonant frequencies and the drift mobilities. On the other hand, the impedance spectral analysis of the Y/InSe/Au interfaces in the frequency range of 0.01-1.80 GHz, revealed negative capacitance effect associated with band filter features that exhibit maximum transition line at 1.17 GHz. This value nominates the interface as a member of filter classes in the gigahertz technology. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 7Citation - Scopus: 7Illumination Effects on the Capacitance Spectra and Signal Quality Factor of Al/Inse Microwave Sensors(Springer, 2013) Qasrawi, A. F.Amorphous indium selenide thin films have been used in the design of a microwave-sensitive Schottky barrier. The illumination effects on the capacitance spectra, on the signal quality factor, and on the capacitance (C)-voltage (V) characteristics of the Al/InSe/C device are investigated. Particular shifts in the amplitude and in the resonance peaks of the capacitance spectra which were studied in the frequency range of 10.0 kHz to 3.0 GHz are observed. While the photoexcitation of these devices increased the capacity level by similar to 1.6 times the original magnitude, the dark quality factor, which was 2.2 x 10(6) at 3.0 GHz, fell to 1.2 x 10(6) when subjected to luminance of 14.7 klux. Analysis of the C-V curves recorded at signal power ranging from wireless local area network (LAN) levels to the maximum output power of third generation (3G) mobiles reflected high tunability of capacitance upon increasing the voltage or power. The tunability of the biased capacitance was much more pronounced in the light than in the dark. The obtained characteristics of the Al/InSe/C sensors indicate their usability in radio and microwave technology.Article Citation - WoS: 11Citation - Scopus: 12Effect of Au Nanosandwiching on the Structural, Optical and Dielectric Properties of the as Grown and Annealed Inse Thin Films(Elsevier Science Bv, 2017) Omareya, Olfat A.; Qasrawi, A. F.; Al Garni, S. E.In the current work, the structural, optical and dielectric properties of the InSe/Au/InSe nanosandwiched structures are investigated by means of X-ray diffraction and UV-visible light spectrophotometry techniques. The insertion of a 20 and 100 nm thick Au metal slabs between two InSe layers did not alter the amorphous nature of the as grown InSe films but decreased the energy band gap and the free carrier density. It also increased; the absorption ratio and the values of dielectric constant by similar to 3 times. The insertion of 100 nm Au layers as a nanosandwich enhanced the drift mobility (31.3 cm(2)/V s) and plasmon frequency (1.53 GHz) of the InSe films. On the other hand, upon annealing, a metal induced crystallization process is observed for the InSe/Au (100 nm)/InSe sandwiches. Particularly, while the samples sandwiched with a layer of 20 nm thickness hardly revealed hexagonal gamma -In2Se3 when annealed at 300 degrees C, those sandwiched with 100 nm Au slab, displayed well crystalline phase of hexagonal gamma -In2Se3 at annealing temperature of 200 degrees C. The further annealing at 300 degrees C, forced the appearing of the orthorhombic In4Se3 phase. Optically, the annealing of the InSe/Au(100 nm)/InSe at 200 degrees C improved the absorption ratio by similar to 9 times and decreased the energy band gap. The nanosandwiching technique of InSe seems to be promising for the engineering of the optical properties of the InSe photovoltaic material.Article Citation - WoS: 20Citation - Scopus: 21Temperature-Tuned Band Gap Characteristics of Inse Layered Semiconductor Single Crystals(Elsevier Sci Ltd, 2020) Isik, M.; Gasanly, N. M.Layered structured InSe has attracted remarkable attention due to its effective characteristics utilized especially in optoelectronic device technology. This point directs researchers to investigate optical properties of InSe in great detail. The temperature dependent band gap characteristics of InSe and analyses performed on this dependency have been rarely studied in literature. Here, temperature-dependent transmission and room temperature reflection experiments were performed on InSe layered single crystals. The band gap energy was found around 1.22 eV at room temperature and 1.32 eV at 10 K. The temperature-gap energy dependency was analyzed using Varshni and O'Donnell-Chen models to reveal various optical parameters of the crystal. The structural characteristics; crystalline parameters like lattice constants, lattice strain, dislocation density and atomic compositions of InSe were also determined from the analyses of XRD and EDS measurements.Article Citation - WoS: 9Citation - Scopus: 10Growth and Characterization of Inse/Ge Interfaces(Elsevier Gmbh, Urban & Fischer verlag, 2017) Al Garni, S. E.; Omareye, Olfat A.; Qasrawi, A. F.In the current study, we report the effect of insertion of a 200 nm thick Ge film between two layers of InSe. The Ge sandwiched InSe films are studied by means of X-ray diffraction technique, energy dispersion X-ray spectroscopy attached to a scanning electron microscope, optical spectrophotometry and light power dependent photoconductivity. It was observed that, The InSe prefers the growth of InSe monophase when deposited onto glass and the growth of gamma-In2Se3 when deposited onto InSe/Ge substrate. The three layers interface (InSe/Ge/gamma-In2Se3) exhibits a Ge induced crystallization process at annealing temperature of 200 degrees C. The optical analysis has shown that the InSe films exhibit a redshift upon Ge sandwiching. In addition, the conduction and valence bands offsets at the first interface (InSe/Ge) and at the second (Ge/gamma-In2Se3) interface are found to be 0.55 eV and 1.0 eV, and 0.40eVand 1.38 eV, respectively. Moreover, the photocurrent of the Ge sandwiched InSe exhibited higher photocurrent values as compared to those of InSe. On the other hand, the dielectric spectral analysis and modeling which lead to the identifying of the optical conduction parameters presented by the plasmon frequency, electron scattering time, free electron density and drift mobility have shown that the Ge sandwiching increased the drift mobility values from 10 cm(2)/Vs to 42 cm(2)/Vs. The main plasmon frequency also increased from 1.08 to 1.68 GHz. (C) 2017 Elsevier GmbH. All rights reserved.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.
