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Article Citation - WoS: 8Citation - Scopus: 10Thickness Effects on the Dielectric Dispersion and Optical Conductivity Parameters of Cuo Thin Films(Wiley, 2020) Qasrawi, Atef F.; Qasrawı, Atef Fayez Hasan; Hamamdah, Alaa A.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringIn this article, the effect of film thickness on the structural, optical, dielectric, and optical conductivity parameters of CuO thin films are reported. CuO thin films which are prepared by the physical vapor deposition technique under vacuum pressure of 10(-5) mbar with various thicknesses in the range of 50 to 1000 nm are observed to exhibit amorphous nature of growth. The values of the energy bands gaps, the spectral response of the dielectric constant and of the optical conductivity parameters are highly sensitive to the film thickness. Particularly, while the 50 nm thick CuO films exhibits quantum confinement which forces the material to have wide band gap (2.70 eV), the thicker films display an energy band gap in the infrared range of spectrum. It was also observed that the thicker the films, the more pronounced the nonlinear dielectric response. In addition, analysis of the optical conductivity parameters using Drude-Lorentz approach for optical conduction has shown that the 50 nm thick films can display drift mobility value of 4.65 cm(2)/Vs accompanied with plasmon frequency of 1.20 GHz and free carrier density of 7.5x10(17) cm(3). The Drude-Lorentz analysis has also shown that the free carrier density and the plasmon frequency of CuO decreases with increasing film thickness. This decrement is accompanied with enhancement in the drift mobility values which reaches 12.56 cm(2)/V s as the film thickness exceeds 250 nm. Such features of the thin layer of CuO make them suitable for the production of nano/microthin film transistors.Article Citation - WoS: 2Citation - Scopus: 2Effect of Insertion of Aluminum Nanosheets on the Structural, Optical and Dielectric Properties of Stacked Layers of Selenium(Natl inst R&d Materials Physics, 2019) Qasrawi, A. F.; Qasrawı, Atef Fayez Hasan; Abu Al Rob, O. H.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringIn this work, the time dependent metal induced crystallization process in stacked layers of selenium that are sandwiched with aluminum nanosheets of thicknesses of 50 nm are investigated by means of X-ray diffraction and optical spectrophotometry techniques. The Al nanosheets motivated the growth of orthorhombic phases of selenium and lowered the energy bang gap of the amorphous films from 2.26 to 1.82 eV when the orthorhombic phase is achieved. The time dependent monitoring of the structural and optical properties over eighteen months have shown that both of the orthorhombic and amorphous phases exhibit a second transformation to hexagonal and stabilize at that phase within ten days of the growth time. The presence of the aluminum nanosheets enhanced the light absorbability by 15 and 5 times in the orthorhombic and hexagonal phases, respectively. In addition, the dielectric spectra of the studied films display similar characteristics in the hexagonal phase with slight differences that results from Al nanosheets. The dielectric spectra for both of the amorphous and orthorhombic phases displayed resonance peaks in the visible and infrared ranges of light. The structural and optical analysis that are carried out through this study represent a guide for using the selenium films in optoelectronic technology.Article Citation - WoS: 3Citation - Scopus: 3Enhancement of the Performance of the Cu2se Band Filters Via Yb Nanosandwiching(Wiley, 2019) Khusayfan, Najla M.; Qasrawı, Atef Fayez Hasan; Qasrawi, A. F.; Khanfar, Hazem K.; Qasrawı, Atef Fayez Hasan; Department of Electrical & Electronics Engineering; Department of Electrical & Electronics EngineeringIn this article, we report the experimental and theoretical modeling on the band pass filters that are made of two thin film layers of Cu2Se coated onto aluminum substrates and nanosandwiched with 50 nm ytterbium layers. The nanosandwiching of Yb between two layers of Cu2Se is found to decrease the lattice constant, the defect density, and the strain and increase the grain size in the Cu2Se. Electrically, it is observed that, Al/Cu2Se/Al structure exhibits wave trap characteristics with notch frequency of 1.31 GHz. The Yb-layers improved the performance of the band pass filters by increasing the amplitude of the reflection coefficients, increasing the return loss values and decreasing the voltage standing wave ratios. The calculated conduction and wave trapping parameters nominate the Yb-nanosandwiched Cu2Se films for use in communication technology as they exhibit negative capacitance effect and narrow band pass range.
