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Article Citation - WoS: 8Citation - Scopus: 8Optical Interactions in the Inse/Cdse Interface(Wiley-v C H verlag Gmbh, 2016) Qasrawi, A. F.; Rabbaa, S.In this work, the structural and optical properties of the InSe/CdSe heterojunction are investigated by means of X-ray diffraction and ultraviolet-visible light spectrophotometry techniques. The hexagonal CdSe films that were deposited onto amorphous InSe and onto glass substrates at a vacuum pressure of 10(-5)mbar, exhibited interesting optical characteristics. Namely, the absorption, transmission, and reflection spectra that were recorded in the incident light wavelength range of 300-1100nm, for the InSe, CdSe, and InSe/CdSe interface revealed direct allowed transition energy bandgaps of 1.44, 1.85, and 1.52eV, respectively. The valence-band offset for the interface is found to be 0.36eV. On the other hand, the dielectric constant spectral analysis displayed a large increase in the real part of the dielectric constant associated with decreasing frequency below 500THz. In addition, the optical conductivity spectra that were analyzed and modeled in accordance with the Drude theory displayed a free-carrier average scattering time of 0.4fs and a drift mobility of 6.65cm(2)V(-1)s(-1) for the InSe/CdSe interface. The features of this interface nominate it as a promising member for the production of optoelectronic Schottky channels and as thin-film transistors.Article Citation - WoS: 10Citation - Scopus: 9Structural and Optoelectronic Properties of Moo3 Interfaces(Wiley-v C H verlag Gmbh, 2019) Alharbi, Seham Reef; Qasrawi, Atef FayezIn 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.Article Citation - WoS: 9Absorption and Optical Conduction in Inse/Znse Thin Film Transistors(World Scientific Publ Co Pte Ltd, 2016) Al Garni, S. E.; Qasrawi, A. F.In this work, (n)InSe/(p)ZnSe and (n)InSe/(p)ZnSe/(n)InSe heterojunction thin film transistor (TFT) devices are produced by the thermal evaporation technique. They are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion X-ray spectroscopy and optical spectroscopy techniques. While the InSe films are found to be amorphous, the ZnSe and InSe/ZnSe films exhibited polycrystalline nature of crystallization. The optical analysis has shown that these devices exhibit a conduction band offsets of 0.47 and valence band offsets of 0.67 and 0.74 eV, respectively. In addition, while the dielectric spectra of the InSe and ZnSe displayed resonance peaks at 416 and 528 THz, the dielectric spectra of InSe/ZnSe and InSe/ZnSe/InSe layers indicated two additional peaks at 305 and 350 THz, respectively. On the other hand, the optical conductivity analysis and modeling in the light of free carrier absorption theory reflected low values of drift mobilities associated with incident alternating electric fields at terahertz frequencies. The drift mobility of the charge carrier particles at femtoseconds scattering times increased as a result of the ZnSe sandwiching between two InSe layers. The valence band offsets, the dielectric resonance at 305 and 350 THz and the optical conductivity values nominate TFT devices for use in optoelectronics.Article Citation - WoS: 7Citation - Scopus: 7Enhancements of Light Absorbability, Optical Conductivity, and Terahertz Cutoff Frequency in Stacked Layers of Selenium Via Ag Nanoslabs Sandwiching(Wiley-v C H verlag Gmbh, 2019) Qasrawi, Atef F.; Abu Al Rob, Osama H.Herein, the effects of insertion of Ag layer of thickness of 100 nm between two stacked layers of selenium are investigated by means of X-ray diffraction, scanning electron microscopy, and optical spectrophotometry techniques. While the structural analysis shows the amorphous nature of growth of the stacked layers of Se, the morphology analysis shows the formation of nanorods and nanowires that exhibit lengths and diameters in the ranges of 1.5-2.5 mu m and 36-146 nm, respectively. The optical spectroscopy analysis shows that the presence of Ag between stacked layers of selenium enhances the light absorbability, increases the optical conductivity, and widens the range of the terahertz cutoff frequency. In addition, Ag layers increase the drift mobility from 15.07 to 35.64 cm(2) Vs(-1) and extend the plasmon frequency domain of stacked layers of selenium from 0.45-5.60 to 0.62-5.90 GHz. The calculated optical conductivity parameters and the spectral analysis of the terahertz cutoff frequency that vary in the range of 0.35-13.20 THz indicate the applicability of the Ag sandwiched selenium stacked layers as terahertz cavities suitable for visible-light communications as band-pass filters.Article Citation - WoS: 11Citation - Scopus: 11in Situ Monitoring of Heat Assisted Oxidation and Its Effects on the Structural, Dielectric and Optical Conductivity Parameters of Pb Thin Films as Promising Terahertz Transmitters(Iop Publishing Ltd, 2019) Qasrawi, A. F.; Abu Ghannam, Arwa N.In this work, thermal vacuum deposited lead thin films are subjected to an in situ monitoring of the oxidation process during heating in the temperature range of 300-480 K by the x-ray diffraction technique. The heating effects on the crystallinity, phase formation and structural parameters are additionally investigated with the help of computer simulation to explore the possible formed oxides. In addition, the heating effects of the optical transmission, reflection and absorption, optical conduction and terahertz signal transmission spectra are also investigated. It is found that, the cubic crystalline Pb films comprises tetragonal Pb3O4 in it's as grown form. When heated, while the Pb3O4 content increases from 18.5% to 21.3%, tetragonal PbO phase with weight of 30.9% is formed. Even though more than half of the film content relates to the oxides after the samples were left to cool, the microstrain and defect density in the films decreased and the grain size increased. Optically, the oxidation process enhanced, the light transitivity, reflectivity and decreased the absorption coefficient. Two energy band gaps one is assigned to Pb3O4 with value of 2.12 eV before heating and the other is assigned to PbO with value of 2.60 eV after cooling are detected. Dielectrically, the oxidation increased the real part and the quality factor in the infrared region of light. On the other hand, the optical conductivity analyses which are treated via Drude-Lorentz approach has shown that Pb films exhibit plasmon frequency and mobility values of 3.2 GHz and 0.62 cm(2) V-1 s(-1), respectively. The oxidation slightly lowered the optical conductivity parameters. Application directed analysis of the terahertz cutoff frequency has shown that the oxidized Pb films behaves as promising layers for use as terahertz wave transmitters suitable for visible light communications.
