Yazar "Ates, Sule" seçeneğine göre listele

Listeleniyor 1 - 3 / 3
  • Küçük Resim Yok
    Öğe
    Photonic bandgap engineering in (VO2) n /(WSe2) n photonic superlattice for versatile near- and mid-infrared phase transition applications
    (Iop Publishing Ltd, 2022) Basyooni, Mohamed A.; Zaki, Shrouk E.; Tihtih, Mohammed; Eker, Yasin Ramazan; Ates, Sule
    The application of the photonic superlattice in advanced photonics has become a demanding field, especially for two-dimensional and strongly correlated oxides. Because it experiences an abrupt metal-insulator transition near ambient temperature, where the electrical resistivity varies by orders of magnitude, vanadium oxide (VO2) shows potential as a building block for infrared switching and sensing devices. We reported a first principle study of superlattice structures of VO2 as a strongly correlated phase transition material and tungsten diselenide (WSe2) as a two-dimensional transition metal dichalcogenide layer. Based on first-principles calculations, we exploit the effect of semiconductor monoclinic and metallic tetragonal state of VO2 with WSe2 in a photonic superlattices structure through the near and mid-infrared (NIR-MIR) thermochromic phase transition regions. By increasing the thickness of the VO2 layer, the photonic bandgap (PhB) gets red-shifted. We observed linear dependence of the PhB width on the VO2 thickness. For the monoclinic case of VO2, the number of the forbidden bands increase with the number of layers of WSe2. New forbidden gaps are preferred to appear at a slight angle of incidence, and the wider one can predominate at larger angles. We presented an efficient way to control the flow of the NIR-MIR in both summer and winter environments for phase transition and photonic thermochromic applications. This study's findings may help understand vanadium oxide's role in tunable photonic superlattice for infrared switchable devices and optical filters.
  • Küçük Resim Yok
    Öğe
    Study of the local structure and electrical properties of gallium substituted LLZO electrolyte materials
    (Elsevier Science Sa, 2019) Aktas, Sevda; Ozkendir, Osman Murat; Eker, Yasin Ramazan; Ates, Sule; Atav, Ulfet; Celik, Gultekin; Klysubun, Wantana
    The solid-state lithium batteries are more stable than the batteries with liquid electrolyte, however their performance are also worse especially due to the low ionic conduction of their electrolyte. Garnet-type Li7La3Zr2O12 is a promising solid-state electrolyte candidate for lithium batteries. In this work the influence of gallium substitution on the electrical, crystal and electronic structure properties in the Li7La3Zr2O12 material were studied. Li7-3xGaxLa3Zr2O12 solid electrolytes were synthesized by solid state reaction method and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), AC impedance spectroscopy and X-ray absorption spectroscopy (XAS) techniques. XRD and XAS analyses showed that the x = 0.05 sample is formed in the tetragonal phase with a space group of I4(1)/ acd:2 and the rest are formed in the cubic phase with a space group of I-43d due to strong coupling between outer shell electrons of the oxygen (O) and gallium (Ga) atoms. Electrochemical impedance spectroscopy (EIS) studies indicated that the tetragonal phase has the highest ionic conductivity, 3.04 x 10(-6) S cm(-1), among all other cubic phases. (C) 2019 Published by Elsevier B.V.
  • Küçük Resim Yok
    Öğe
    Thermionic Emission of Atomic Layer Deposited MoO3/Si UV Photodetectors
    (Mdpi, 2023) Basyooni, Mohamed A.; Gaballah, A. E. H.; Tihtih, Mohammed; Derkaoui, Issam; Zaki, Shrouk E.; Eker, Yasin Ramazan; Ates, Sule
    Ultrathin MoO3 semiconductor nanostructures have garnered significant interest as a promising nanomaterial for transparent nano- and optoelectronics, owing to their exceptional reactivity. Due to the shortage of knowledge about the electronic and optoelectronic properties of MoO3/n-Si via an ALD system of few nanometers, we utilized the preparation of an ultrathin MoO3 film at temperatures of 100, 150, 200, and 250 degrees C. The effect of the depositing temperatures on using bis(tbutylimido)bis(dimethylamino)molybdenum (VI) as a molybdenum source for highly stable UV photodetectors were reported. The ON-OFF and the photodetector dynamic behaviors of these samples under different applied voltages of 0, 0.5, 1, 2, 3, 4, and 5 V were collected. This study shows that the ultrasmooth and homogenous films of less than a 0.30 nm roughness deposited at 200 degrees C were used efficiently for high-performance UV photodetector behaviors with a high sheet carrier concentration of 7.6 x 10(10) cm(-2) and external quantum efficiency of 1.72 x 10(11). The electronic parameters were analyzed based on thermionic emission theory, where Cheung and Nord's methods were utilized to determine the photodetector electronic parameters, such as the ideality factor (n), barrier height (f(0)), and series resistance (R-s). The n-factor values were higher in the low voltage region of the I-V diagram, potentially due to series resistance causing a voltage drop across the interfacial thin film and charge accumulation at the interface states between the MoO3 and Si surfaces.