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Article Citation - WoS: 1Citation - Scopus: 1Ab Initio Study of Structural and Electronic Properties of Single Crystal and Core/Shell Ii-Vi Semiconductor Nanowires(Elsevier, 2016) Pekoz, R.Structural and electronic properties of pristine and H-passivated wurtzite type ZnSe, ZnTe nanowires and ZnX/ZnY (X = Se(Te) and Y = Te(Se)) core/shell nanowires oriented along the [0001] direction have been investigated using first-principles calculations. The changes in the electronic structure of the nanowires due to the quantum confinement and morphology have been searched. Quantum confinement increases the band gap energy as the diameters of ZnSe and ZnTe nanowires decrease. Both homostructured and heterostructured nanowires are found to show a semiconducting character with direct band gaps at Gamma-point. Changing the morphology from homostructured nanowires to heterostructured core/shell nanowires has an important impact on the electronic structure. For instance, the charge separation of electrons and holes along the infinite direction of core/shell nanowires shows a strong preference for electron(hole) states localized inside ZnSe(ZnTe) regions. (C) 2016 Elsevier B.V. All rights reserved.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: 12Citation - Scopus: 14Engineering the Structural, Optical and Dielectric Properties of Znse Thin Films Via Aluminum Nanosandwiching(Elsevier Gmbh, 2019) Qasrawi, A. F.; Alsabe, Ansam M.In this work, two stacked layers of ZnSe thin films are nanosandwiched with aluminum slabs of variable thickness in the range of 10-100 nm. The films which are studied by the X-ray diffraction and ultra-violet visible light spectroscopy techniques exhibit interesting features presented by extension of the cubic lattice parameter, increase in the grain size and reduction in both of the microstrains and defect density. The Al nanosandwiching successfully engineered the energy band gap through narrowing it from 2.84 to 1.85 eV. In addition, the Al nanosandwiching is observed to form interbands that widens upon increasing the Al layer thickness. It also changed the electronic transition nature from direct allowed to direct forbidden type. Moreover, remarkable enhancement in the light absorbability by 796 times is observed near 1.72 eV for two stacked ZnSe layers nanosandwiched with Al slab of thickness of 100 nm. The dielectric constant is also increased three times and the dielectric tenability vary in the range of 3.0-1.2 eV. The nonlinearity in the dielectric spectra and the engineering of the band gap that become more pronounced in the presence of Al slabs make the ZnSe more attractive for nonlinear optical applications.Article Citation - WoS: 5Citation - Scopus: 6Influence of Temperature on Optical Properties of Electron-Beam Znse Thin Film(Iop Publishing Ltd, 2020) Gullu, H. H.; Isik, M.; Gasanly, N. M.; Parlak, M.Structural and optical properties of ZnSe thin films grown by electron-beam evaporation technique were reported in the present paper. X-ray diffraction pattern exhibited a single peak around 27 degrees which is well-suited with cubic phase of the films. Energy dispersive X-ray spectroscopy analyses resulted in atomic composition ratio of Zn/Se nearly 1.0 which corresponds to the chemical formula of ZnSe. Transmission experiments were performed at various temperatures in between 10 and 300 K. The analyses of the transmission data showed that direct band gap energy of the ZnSe thin films increases from 2.72 to 2.83 eV as temperature was reduced to 10 K from room temperature. The Varshni and O'Donnell-Chen models giving the temperature-band gap energy relation were used to get various optical parameters of the evaporated thin films. Analyses resulted in absolute zero temperature band gap energy as 2.83 eV, temperature coefficient as -5.8 x 10(-4) eV K-1 and average phonon energy as 16 meV. Urbach tail state energies were also calculated using absorption coefficient in the low photon energy region as increasing from 173 meV (300 K) to 181 meV (10 K) with decreasing ambient temperature.
