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Article Citation - WoS: 9Citation - Scopus: 8Exploring the Optical Dynamics in the Ito/As2< Interfaces(Springer, 2019) Al Garni, S. E.; Qasrawi, A. F.In this work, the effects of indium tin oxide (ITO) substrates on the structural, compositional, optical dielectric and optical conduction properties of arsenic selenide thin films are investigated. The As2Se3 films which are prepared by the thermal deposition technique under vacuum pressure of 10(-5) mbar exhibit an induced crystallization process, improved stoichiometry, increased optical transmittance in the visible range of light and increased dielectric response in the infrared range of light upon replacement of glass substrates by ITO. The ITO/As2Se3 interfaces exhibit conduction and valence band offset values of 0.46 eV and 0.91 eV, respectively. The experimental optical conductivity spectra are theoretically reproduced with the help of the Drude-Lorentz approach for optical conduction. In accordance with this approach, owing to the improved crystallinity of the arsenic selenide, the deposition of As2Se3 onto ITO substrates increases the drift mobility value from similar to 17.6 cm(2)/Vs to 34.6 cm(2)/Vs. It also reduces the density of free carriers by one order of magnitude. The ITO/As2Se3/C heterojunction devices which are tested as band filters which may operate in the frequency domain of 0.01-3.0 GHz revealed low pass filter characteristics below 0.35 GHz and band pass filter characteristics in the remaining spectral range.Article Citation - WoS: 5Citation - Scopus: 4Nickel Doping Effects on the Structural and Dielectric Properties of Ba(zn1/3< Perovskite Ceramics(Springer, 2021) Qasrawi, A. F.; Sahin, Ethem Ilhan; Emek, MehribanThe effects of nickel doping into Ba(Zn1/3Nb2/3)O-3 (acronym: BZN) ceramics is structurally, morphologically and electrically investigated. The nickel substitution in sites of Zn which was carried out by the solid state reaction technique strongly enhanced the structural, morphological and electrical performances of the BZN. Specifically, while the lattice constant and crystallite sizes increased, the microstrain and the defect density decreased. The relative density of the BZN ceramics increased from 95.40% to 98.24% upon doping of Ni with content of x = 0.05. In addition, the Ni doping increased the values of electrical conductivity without significant changes in the dielectric constant values. It is also observed that the doping the BZN ceramics highly altered the temperature dependent variation of the relative dielectric constant. In the temperature range of 293-473 K, the x = 0.05 Ni doped BZN samples were less sensitive to temperature. The dynamics of the temperature dependent dielectric response is dominated by the coupled defects excitation mechanisms. Both of the temperatures and frequency dependent dielectric constant, dielectric loss and electrical conductivity suggests that the Ni doped Ba(Zn1/3Nb2/3)O-3 ceramics is more appropriate for electronic device fabrication than the pure ones.Article Citation - WoS: 5Citation - Scopus: 6Structural, Optical, Dielectric and Electrical Properties of Al-Doped Znse Thin Films(Springer, 2019) Kayed, T. S.; Qasrawi, A. F.; Elsayed, Khaled A.In this work, the heavy aluminum doping effects on the compositional, structural, optical, dielectric and electrical properties of ZnSe thin films are investigated. It is observed that the Zn/Se compositional ratio increases with increasing Al content. The major cubic phase of ZnSe becomes more pronounced compared to the hexagonal phase. In addition, the presence of Al in the structure of ZnSe causes lattice constant contraction, decreased the grain size and increased both of the strain and defect density. Optically, the Al doping increased the light absorbability and widens both of the energy band gap and energy interbands which are present in the band gap of ZnSe films. Moreover, the Al doping into ZnSe lowers the high frequency dielectric constant and enhances the optical conductivity. On the other hand, the capacitance spectra which are studied in the frequency domain of 0.01-1.80GHz displayed negative capacitance effect associated with resonance-antiresonance phenomena upon doping of ZnSe with Al. Such enhancements in the physical properties of ZnSe that are achieved via Al doping make the zinc selenide thin films more appropriate for electronic and optoelectronic technological applications.Article Citation - WoS: 11Citation - Scopus: 11Formation and Characterization of Cd2s3< Polycrystalline Films Onto Glass and Lanthanum Substrates(Springer, 2019) Qasrawi, A. F.; Omareya, Olfat A.In this article, the structural, optical and dielectric properties of the rarely investigated Cd2S3 thin films are reported. Particularly, Cd2S3 thin films prepared by the thermal evaporation technique onto glass, and 150-nm-thick lanthanum transparent substrate studied by means of energy-dispersive structural analysis have shown that the Cd2S3 thin films are of polycrystalline nature. The hexagonal unit cell parameters, which slightly differ from that of CdS, increased upon replacement of glass with lanthanum. All the other structural parameters including the grain size, strain and defect density are accordingly affected. While the optical band gap increased when La replaces glass, the high-frequency dielectric constant decreased. On the other hand, the Drude-Lorentz modeling of the dielectric spectra has shown that the La/Cd2S3 thin films are promising materials for production of thin film transistors as they exhibit drift mobility values of approximate to 13.3cm(2)/Vs. The response of the glass/Cd2S3 and La/Cd2S3 interfaces to the incident electromagnetic light is associated with hole-plasmon interactions that are limited by plasmon frequency values in the range of 0.4-8.1GHz. Such property makes this material attractive as microwave band pass/reject filters.
