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Article Citation - WoS: 12Citation - Scopus: 12Band Offsets, Optical Conduction, and Microwave Band Filtering Characteristics of Γ-in2se3< Heterojunctions(Wiley-v C H verlag Gmbh, 2020) Qasrawi, Atef F.; Kmail, Reham R.Herein, the design and experimental characterization of gamma-In2Se3/CuO interfaces are considered. Thin films of gamma-In(2)Se(3)are coated with thin layers of CuO at room temperature. The heterojunction device is structurally, morphologically, and optically characterized. It is observed that the coating of CuO onto gamma-In(2)Se(3)engenders the formation of CuSe(2)at the ultrathin interface. The gamma-In2Se3/CuO heterojunctions exhibit maximum possible conduction and valence band offsets of values 0.47 and 0.96 eV, respectively. The dielectric spectra display two dielectric resonance peaks at 2.96 and 1.78 eV. In addition, analyses of the optical conductivity spectra reveal accurate drift mobility and plasmon frequency values of 31.31 cm(2) Vs(-1)and 1.5 GHz, respectively. The ability of the device to control the signal propagation at gigahertz level is experimentally tested by the impedance spectroscopy technique which proved the ability of the device to behave as bandpass filters of notch frequency of 1.49 GHz. The gamma-In2Se3/CuO heterojunction devices are also observed to display terahertz cutoff frequency values of approximate to 24 THz in the infrared (IR) range of incident photon energy and approximate to 193 THz in the ultraviolet light range. The nonlinear optical performance of the device nominates it for use as terahertz/gigahertz band filters.Article Citation - WoS: 9Citation - Scopus: 11Thickness 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: 3Citation - Scopus: 3Enhancement of Nonlinear Optical and Dielectric Properties of Cu2o Films Sandwiched With Indium Slabs(Wiley-v C H verlag Gmbh, 2020) Omar, Ahmad; Qasrawi, Atef F.In this work, the effects of the insertion of indium slabs of thickness 100 nm on the performance of stacked layers of Cu2O are reported. Cu2O/In/Cu2O thin films coated onto ultrasonically cleaned glass substrates are structurally, morphologically, optically, and dielectrically studied. The glassy films of Cu2O display larger, well-ordered grains in an amorphous sea of Cu2O upon insertion of indium slabs between layers of Cu2O. Optically, the indium slabs increase the light absorbability in the IR region by 12.5 times, narrow the energy bandgap, and widen the energy band tails region. They also enhance the nonlinearity in the dielectric response and increase the dielectric constant values by 2.5 times. In addition, the optical conductivity parameters are obtained from the fittings of the dielectric spectra. The analyses reveal an enhancement in the drift mobility, plasmon frequency, and free carrier density via stacking of the indium layer between layers of Cu2O. The drift mobility and plasmon frequency values reach 232.4 cm(2) V-1 s(-1) and 3.95 GHz at a reduced hole-plasmon frequency value of 6.0 x 10(14) Hz (2.48 eV). The values are promising as they indicate the applicability of Cu2O/In/Cu2O interfaces in optoelectronics as thin film transistors and electromagnetic wave cavities.Article Citation - WoS: 7Citation - Scopus: 8Nonlinear Optical Performance of Cdo/Inse Interfaces(Iop Publishing Ltd, 2020) AlGarni, Sabah E.; Qasrawi, A. F.In this article, the growth nature, structural and optical properties of CdO/InSe interfaces are investigated. The CdO/InSe interfaces are prepared by the thermal vacuum deposition technique. Structurally, while the CdO exhibited cubic structure, the InSe layer was amorphous in nature. The morphological analyses have shown that the interface is composed of randomly distributed circular grains of average sizes of similar to 170 nm. The interfacing of the CdO and InSe resulted in enhancing the light absorbability of CdO by similar to 21 times in the IR range. It also showed well aligned conduction bands and valence band offset of 0.72 eV. The Drude-Lorentz modeling of the imaginary part of the dielectric spectra of the CdO/InSe interfaces has shown that the device is suitable for the fabrication of field effect transistors. The drift mobility of free carriers at the interface reached 42.27 cm(2)/Vs. In addition, a quality factor larger than 10(3) is achieved in the IR range indicating the suitability of these optical interfaces to store electromagnetic energy. These properties are important as they shows the applicability of the CdO/InSe interface in solar cells and optoelectronics as optical signal receivers or converters.
