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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: 8Citation - Scopus: 7Negative Capacitance Effect in Ag/-in2< Dual Band Stop Filters(Springer, 2019) Khanfar, Hazem K.; Qasrawi, A. F.; Shehada, Sufyan R.In the current study, a 1.5m thick three channel microwave band filter is designed and characterized. The thin film device which was constructed from the indium selenide, cadmium sulfide and cadmium selenide stacked dielectric materials sandwiched between silver and carbon films is studied by means of x-ray diffraction, energy dispersive x-ray analysis and impedance spectroscopy techniques. It was observed that the Ag thin film substrate induced the formation of the hexagonal -In2Se3 phase of indium selenide. The x-ray analysis has also shown that the deposition of hexagonal CdS over Ag/-In2Se3 and that of hexagonal CdSe over -In2Se3/CdS under vacuum pressure of 10(-8) bar is of a highly strained and mismatched physical nature. The impedance spectroscopy analysis in the frequency domain of 0.10-1.80GHz has shown that; while the Ag/-In2Se3/C channel exhibit negative capacitance (NC) effects in the frequency domain of 0.10-1.40GHz, the Ag/-In2Se3/CdS/C and the Ag/-In2Se3/CdS/CdSe/C channels displayed a NC feature in the domains of 1.24-1.40GHz and 1.10-1.56GHz, respectively. The fitting of the capacitance spectra in accordance with the modified Ershov model allowed determining the NC and band filtering parameters. It was also observed that, although the Ag/-In2Se3/C channel behaves as a high frequency low pass filter, the second and third channels displayed band stop filter features with notch frequencies of 1.38GHz and 1.49GHz, respectively. The features of the device nominate it for use as a parasitic capacitance canceller and as a three channels microwave filter.
