8 results
Search Results
Now showing 1 - 8 of 8
Article Citation - WoS: 15Citation - Scopus: 17Dielectric Dispersion in Ga2s3< Thin Films(Springer, 2017) Alharbi, S. R.; Qasrawi, A. F.In this work, the structural, compositional, optical, and dielectric properties of Ga2S3 thin films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray analysis, and ultraviolet-visible light spectrophotometry. The Ga2S3 thin films which exhibited amorphous nature in its as grown form are observed to be generally composed of 40.7 % Ga and 59.3 % S atomic content. The direct allowed transitions optical energy bandgap is found to be 2.96 eV. On the other hand, the modeling of the dielectric spectra in the frequency range of 270-1,000 THz, using the modified Drude-Lorentz model for electron-plasmon interactions revealed the electrons scattering time as 1.8 (fs), the electron bounded plasma frequency as similar to 0.76-0.94 (GHz) and the reduced resonant frequency as 2.20-4.60 x10(15) (Hz) in the range of 270-753 THz. The corresponding drift mobility of electrons to the terahertz oscillating incident electric field is found to be 7.91 (cm (2)/Vs). The values are promising as they nominate the Ga2S3 thin films as effective candidates in thin-film transistor and gas sensing technologies.Article Citation - WoS: 9Citation - Scopus: 9Effect of Ytterbium, Gold and Aluminum Transparent Metallic Substrates on the Performance of the Ga2s3< Thin Film Devices(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, the structural, optical, dielectric and electrical properties of the Ga2S3 thin films which are deposited onto transparent thin Al, Yb and Au metal substrates are characterized by means of transmittance electron microscopy, X-ray diffraction, ultraviolet visible light spectroscopy and impedance spectroscopy techniques. The effects of the metallic substrates on the crystalline nature, energy band gap and dielectric spectra are also investigated. The modeling of the dielectric spectra allowed determining the effect of the Al, Yb and Au thin layers on the electron scattering time, the plasmon frequency, free electron density and drift mobility. In addition, a Yb/Ga2S3/Au Schottky barrier and All Ga2S3/Au back to back Schottky barrier devices (metal-semiconductor-metal (MSM) device) are fabricated and characterized by means of capacitance-voltage characteristics and capacitance and conductance spectra in the frequency range of 10-1800 MHz. While the Schottky barrier device displayed three distinct positions of resonance-antiresonance phenomena, the MSM device displayed one peak with narrow bandwidth of 10 MHz. The MSM devices exhibited an inversion, depletion and accumulation modes within a voltage range of 0.25 V width at 250 MHz. The study indicates the applicability of these device as smart capacitive switches, as Plasmon devices and as wavetraps. (C) 2017 Elsevier B.V. All rights reserved.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: 7Design of the Zns/Ge pn Interfaces as Plasmonic, Photovoltaic and Microwave Band Stop Filters(Elsevier Science Bv, 2017) Alharbi, S. R.; Qasrawi, A. F.In the current work, we report and discuss the features of the design of a ZnS (300 nm)/Ge (300 nm)/GaSe (300 nm) thin film device. The device is characterized by the X-ray diffraction, electron microscopy, energy dispersive X-ray spectroscopy (EDS), optical spectroscopy, microwave power spectroscopy and light power dependent photoconductivity. While the X-ray diffraction technique revealed a polycrystalline ZnS coated with two amorphous layers of Ge and GaSe, the hot probe tests revealed the formation of pn interface. The optical spectra which were employed to reveal the conduction and valence band offsets at the ZnS/Ge and Ge/GaSe interface indicated information about the dielectric dispersion at the interface. The dielectric spectra of the ZnS/Ge/GaSe heterojunction which was modeled assuming the domination of surface plasmon interactions through the films revealed a pronounced increase in the drift mobility of free carriers in the three layers compared to the single and double layers. In the scope of the fitting parameters, a wave trap that exhibit filtering properties at notch frequency of 2.30 GHz was designed and tested. The ac signals power spectrum absorption reached similar to 99%. In addition, the photocurrent analysis on the ZnS/Ge/GaSe interface has shown it is suitability for photovoltaic and photosensing applications. (C) 2017 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND licenseArticle Citation - WoS: 1Citation - Scopus: 1Characterization of the Nanosandwiched Ga2s3< Interfaces as Microwave Filters and Thermally Controlled Electric Switches(Elsevier Gmbh, 2018) Alharbi, S. R.; Nazzal, Eman O.; Qasrawi, A. F.In this work, an indium layer of 50 nm thicknesses is sandwiched between two 500 nm thick Ga2S3 layers. The effect of indium nansandwiching on the composition, structure, morphology, light absorbability, capacitance and reactance spectra, and temperature dependent electrical conductivity of the Ga2S3 films are investigated by means of X-ray diffraction, scanning electron microscopy, energy dispersion X-ray spectroscopy, Raman spectroscopy, visible light spectrophotometry, impedance spectroscopy and current voltage characteristics. While the nansandwiched films are observed to exhibit an amorphous nature of structure with indium content of Owing to the nucleation mechanisms that take place during the film growth, the accumulation of some unit cells in groups to form grains should be a significant reason for the existence of many different sizes of grains in the nanosand-wiched films (Alharbi and Qasrawi, 2016). 0, the Raman spectra displayed three vibrational modes at 127.7,145.0 and 274.3 cm(-1). It was also observed that the indium insertion in the structure of the Ga2S3 shrinks the energy band gap by 0.18 eV. The nanosandwiched films are observed to exhibit a semiconductor metal (SM) transition at 310 K. The SM transition is associated with thermal hysteresis that exhibited a maximum value of 16% at 352 K. This behavior of the nanosandwiched films nominate it for use as thermally controlled electric switches. In addition, the impedance spectral analysis in the range of 10-1800 MHz has shown a capacitance tunability of more than 70%. The measurements of the wave trapping property displayed a bandpass/reject filter characteristics above 1.0 GHz which allow using the Ga2S3/In/Ga2S3 thin films as microwave resonator. (C) 2017 Elsevier GmbH. All rights reserved.Article Citation - WoS: 1Citation - Scopus: 1Structural, Optical and Electrical Properties of Ybinse Thin Films(Elsevier Science Sa, 2016) Alharbi, S. R.; Qasrawi, A. F.In this work, the compositional, the structural, the vibrational, the optical and the electrical characterizations of the YbInSe compound are investigated by means of energy dispersion X-ray analysis, scanning electron microscopy and X-ray diffraction, Raman spectroscopy, ultraviolet-visible light spectrophotometry, impedance spectroscopy and temperature dependent electrical conductivity, respectively. The 300 nm thick YbInSe films which were prepared by the co-evaporation of the source materials under a vacuum pressure of 10(-5) mbar, are observed to exhibit nanocrystalline clusters of size of 27 nm regularly distributed among an amorphous structure. The most intensive Raman active lines are observed at 150 and 254 cm(-1). In addition, the optical analysis has shown that the films exhibit a direct forbidden electronic transitions type energy band gap of 1.07 eV. The optical transitions are associated with interband tail states of width of 0.28 eV. Moreover, the real and imaginary parts of dielectric spectra which were analyzed in the frequency range of 270-1000 THz, were analyzed in accordance with the single oscillator and the Lorentz models, respectively. The modeling allowed determining the oscillator and dispersion energies, the terahertz free carrier scattering time, the free holes effective mass, the carrier density, the drift mobility and the reduced resonant frequency for the YbinSe films. In the electronic part of study, the temperature dependent dc electrical conductivity analysis, indicated the domination of the variable range hopping transport mechanism below 335 K, the thermal excitation of charge carriers in the range of 337390 K and the extrinsic-intrinsic transition property at 390 K. The ac conductivity spectra which were recorded in the frequency range of 10-1500 MHz, revealed the domination of the correlated barrier hopping of free carriers between pairs of localized states at the Fermi level. (C) 2016 Elsevier B.V. All rights reserved.Article Citation - WoS: 18Citation - Scopus: 21Engineering the Optical and Dielectric Properties of the Ga2s3< Nanosandwiches Via Indium Layer Thickness(Springer, 2018) Nazzal, Eman O.; Qasrawi, A. F.; Alharbi, S. R.In this study, the effect of the nanosandwiched indium slab thickness (20-200 nm) on the performance of the Ga2S3/In/Ga2S3 interfaces is explored by means of X-ray diffraction, Raman spectroscopy, and optical spectroscopy techniques. The indium slab thickness which was varied in the range of 20-200 nm is observed to enhance the visible light absorbability of the Ga2S3 by 54.6 times, engineered the energy band gap in the range of 3.7-1.4 eV and increases the dielectric constant without, significantly, altering the structure of the Ga2S3. The broad range of the band gap tunability and the increased absorbability nominate the Ga2S3 thin films for photovoltaic applications. In addition, the dielectric spectral analysis and modeling have shown that a wide variety in the plasmon resonant frequency could be established within the Ga2S3/In/Ga2S3 trilayers. The plasmon frequency engineering in the range of 0.56-2.08 GHz which is associated with drift mobility of 12.58-5.76 cm(2)/Vs and electron scattering time at femtosecond level are promising for the production of broad band high frequency microwave filters.Article Citation - WoS: 11Citation - Scopus: 11Optical and Electrical Performance of Yb/Inse Interface(Elsevier Sci Ltd, 2016) Alharbi, S. R.; Qasrawi, A. F.In this study a 300 nm ytterbium transparent thin film is used as substrate to a 300 nm thick InSe thin film. The optical transmittance, reflectance and absorbance of the glass/InSe and Yb/InSe films are measured and analyzed. The optical data allowed determining the effects of the Yb layer on the energy band gap, on the dielectric and on optical conductivity spectra. The band gap of the InSe films shrunk from 2.38/139 to 1.90/1.12 eV upon Yb layer interfacing leading to a band offset of 0.48/0.27 eV. On the other hand, the modeling of the optical conductivity in accordance with the Lorentz theory revealed a free carrier scattering time, carrier density and mobility of 0.225 (fs), 3.0 x 10(19)(cm(-3)) and 2.53 cm(2)/Vs for the Yb/InSe interface, respectively. As these values seem to be promising for employing the Yb/InSe interface in thin film transistor technology, the current voltage characteristics of Yb/InSe/C Schottky diode were recorded and analyzed. The electrical analysis revealed the removal of the tunneling channels by using Yb in place of Al. In addition, the "on/off' current ratios, the Schottky barrier height and the switching voltage of the Yb/InSe/C device are found to be 18.8, 0.76/0.60 eV and 0.53 V, respectively. (C) 2015 Elsevier Ltd. All rights reserved.
