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Article Citation - WoS: 1Citation - Scopus: 1Structural, Optical and Dielectric Performance of Molybdenum Trioxide Thin Films Sandwiched With Indium Sheets(inst Materials Physics, 2020) Abusaa, M.; Qasrawi, A. F.; Kmail, H. K.; Khanfar, H. K.; Department of Electrical & Electronics EngineeringIn this work, we report the enhancements in the structural, optical and dielectric properties of molybdenum trioxide that are achieved by insertion of 50 and 100 nm thick indium sheets between layers of MoO3. The films which are coated onto ultrasonically glass substrates under a vacuum pressure of 10 -5 mbar exhibited metal induced crystallization process upon insertion of indium sheets. Optically, indium sheets tuned the transmittance and reflectance, significantly, increased the absorption coefficient values and formed interbands in the band gap of MoO3. The energy band gap decreased with increasing indium sheets thickness. On the other hand, the insertion of indium layers into the structure of MoO3 is observed to improve the dielectric response of these films to values that nominate them for used in thin film transistor technology. In the same context, the analyses of the optical conductivity which are carried out with the help of Drude-Lorentz approach have shown that the presence of indium sheets can increase the optical conductivity and enhance the plasmon frequency and free charge carrier density of MoO3. The plasmon frequency is tuned in the range of 1.68-7.16 GHz making MoO3 films attractive for plasmonic applications.Article Citation - WoS: 5Citation - Scopus: 4Thickness and Annealing Effects on the Structural and Optical Conductivity Parameters of Zinc Phthalocyanine Thin Films(inst Materials Physics, 2020) Alharbi, S. R.; Qasrawi, A. F.; Khusayfan, N. M.; Department of Electrical & Electronics EngineeringIn this work, the effects of the thin film thicknesses on the structural, optical absorption, energy band gap, dielectric spectra and optical conductivity parameters of the Zinc phthalocyanine thin films are considered. Thin films of ZnPc of thicknesses of 50-600 nm which are coated onto glass substrates are observed to exhibit amorphous nature of growth. The polycrystalline monoclinic ZnPc phase of the films is obtained via annealing the films at 200 degrees C in a vacuum atmosphere. Increasing the ZnPc films thickness shrunk the energy band gap in the B- and Q- bands and decreased both of the optical conductivities and free holes density in the Q-band. The increase in the film thickness is also observed to decrease the plasmon frequency and the drift mobility of holes in the films. The highest dielectric constant is obtained for films of thicknesses of 100 nm. The annealing process enhanced the optical absorption, redshifts the energy band gap value and the critical energy of the absolute maxima of dielectric constant. In addition, while the heat treatment enhanced both of the scattering times at femtosecond level and the drift mobility, it reduced the free holes density, and the plasmon frequency.Article Citation - Scopus: 1Structural and Electrical Performance of Moo3 Films Designed as Microwave Resonators(inst Materials Physics, 2020) Al Garni, S. E.; Qasrawi, A. F.; Alharbi, S. R.; Department of Electrical & Electronics EngineeringIn this work, the effect of the insertion of lithium slabs of thicknesses of 50 nm between stacked layers of MoO3 is considered. Stacked layers of MoO3 comprising lithium slabs are prepared by the thermal evaporation technique onto Au substrates under vacuum pressure of 10(-5) mbar. The effects of Li slabs are explored by the X-ray diffraction, scanning electron microscopy, current-voltage characteristics and impedance spectroscopy techniques in the frequency domain of 0.01-1.80 GHz. While the presence of Li slabs did not alter the amorphous nature of structure, it forced the growth of rod-like grains of diameters of 100-160 nm and lengths of 1.5 mu m. Electrically, the presence of Li in the samples enhanced the rectifying properties of the devices and force reverse to forward current ratios larger than 60 times. Li slabs also controlled the negative capacitance effect and resonance -antiresonance regions in the Au/MoO3/MoO3/C stacked layers. While the Au/MoO3/MoO3/C devices displayed high conductance and low impedance values in the studied frequency domain, the Au/MoO3/Li/MOO3/C devices exhibited low conductance and high impedance mode in the frequency domain of 0.01-0.59 GHz. It is also found that the presence of Li slabs improved the performance of the devices through driving it to exhibit lower reflection coefficient and high return loss values near 0.80 GHz. The features of the devices nominate them for use as RF-Microwave traps or resonators.
