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Article Citation - WoS: 6Citation - Scopus: 6Gold and Ytterbium Interfacing Effects on the Properties of the Cdse/Yb Nanosandwiched Structures(Elsevier Science Bv, 2018) Alharbi, S. R.; Qasrawi, A. F.Owing to the performance of the CdSe as an optoelectronic material used for the production of quantum dots, photosensors and wave traps we here, in this article, report the enhancements in structural and electrical properties that arises from the nanosandwiching of a 40 nm thick Yb film between two films of CdSe (CYbC-40). The CdSe films which were deposited onto glass, Yb and Au substrates are characterized by X-ray diffraction, temperature dependent electrical conductivity and impedance spectroscopy measurements in the frequency range of 10-1800 MHz. The analysis of the XRD patterns have shown that the glass/CdSe/Yb/CdSe films exhibit larger grain size and lower strain, defect density and lower stacking faults compared to the not sandwiched CdSe. In addition, it was observed that the Yb shifts the donor states of the n-type CdSe from 0.44 to 0.29 eV leading to a modification in the built in voltage of the material. On the other hand, the design of the energy band diagram has shown the ability of the formation of the Au/CYbC-40/Yb as Schottky (SB) and the Au/CYbC-40/Au as back to back Schottky barriers (BBSB). While the SB device show low band pass filter characteristics, the BBSB device performed as band stop filters. The BBSB device exhibited negative capacitance effects with filtering features that reveal a return loss of 42 dB at similar to 1440 MHz.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: 4Citation - Scopus: 4Band Offsets and Optical Conduction in the Cdse/Gase Interface(Elsevier Science Bv, 2016) Kayed, T. S.; Qasrawi, A. F.; Elsayed, Khaled A.In this work, the design and characterization of CdSe/GaSe heterojunction is considered. The CdSe/GaSe thin film interface was prepared by the physical vapor deposition technique. Systematic structural and optical analysis were performed to explore the crystalline nature, the optical band gaps, the conduction and valence band offsets, the dielectric spectra, and the frequency dependent optical conductivity at terahertz frequencies. The X-ray diffraction analysis revealed a polycrystalline interface that is mostly dominated by the hexagonal CdSe oriented in the (002) direction. It was also found that the CdSe/GaSe interface exhibits conduction and valence band offsets of 1.35 and 1.23/1.14 eV, respectively. The dielectric spectra displayed two dielectric resonance peaks at 530 and 445 THz. Moreover, the computational fittings of the optical conductivity of the interface revealed a free carrier scattering time of 0.41 (fs) for a free carrier density of 7.0 x 10(18) (cm(-3)). The field effect mobility for the CdSe/GaSe interface was found to be 5.22 (cm(2)/Vs). The remarkable features of this device having large band offsets and qualitative optical conduction dominated by a scattering time in the order of femtoseconds in addition to the dielectric property nominate the device to be used in optoelectronic technology. (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.
