Physics / Fizik

Permanent URI for this collectionhttps://hdl.handle.net/11147/6

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Access Right: Closed AccessAuthor: search.filters.author.Tarhan, Enver

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  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Room Temperature Emission From Single Defects in Wo3 Enhanced by Plasmonic Nanocrystals
    (American Institute of Physics, 2021) Özçeri, Elif; Polat, Nahit; Balcı, Sinan; Tarhan, Enver
    Room temperature light emission from optically active defect centers in two-dimensional layered materials has attracted great interest in recent years owing to the critical applications in the field of quantum information technologies. Therefore, efficient generation, detection, characterization, and manipulation of spatially localized emission from the defect centers are of crucial importance. Here, we report localized, stable, and bright room temperature photoluminescence (PL) emission from defects in WO3. In particular, the experimentally observed polarized and power dependent PL emission shows single photon characteristics. In addition, density functional theory calculations indicate that the source of the emission is most probably oxygen vacancy defects in WO3. The PL emission obtained from the localized defect centers in WO3 at room temperature has been, further, enhanced more than 20 times by using plasmonic gold nanoparticles.
  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Effect of the Synthesis Conditions on the Properties of Co Embedded Porous Si Nanostructures
    (Elsevier Ltd., 2019) Çetinel, Alper; Artunç, Nurcan; Tarhan, Enver
    The electrodeposition of cobalt in the porous silicon (PSi) substrate was investigated in terms of the deposition times and current densities. The PSi/Co samples were characterized by SEM, XRD, Raman, and photoluminescence (PL) spectroscopies. The results indicated that for all current densities, the PL intensities of PSi/Co samples with shorter deposition times (t(s) <= 20 min) increased due to spherical Co nanoparticles (NPs) could be created the new recombination centers, compared to that of the undeposited PSi. On the other hand, the PL intensity of PSi/Co samples significantly decreased at longer deposition times (t(1) > 20 min) because of larger Co NP cluster promoted the formation of non-radiative centers. The increased PL intensities in samples with t(s) were attributed to both the quantum confinement effect and surface effects. PL analyses also suggested that after exposure to air for 60 days, PL characteristics of PSi/Co were stabilized depending on deposition time and current density.
  • Article
    Citation - WoS: 6
    Citation - Scopus: 6
    The Growth of Silver Nanostructures on Porous Silicon for Enhanced Photoluminescence: The Role of Agno3 Concentration and Deposition Time
    (EDP Sciences, 2019) Çetinel, Alper; Artunç, Nurcan; Tarhan, Enver
    Silver nanostructures were obtained by using the electrodeposition method on n-type porous silicon (PSi) under different deposition times and concentrations of AgNO3 solutions. The analyses of the structural and photoluminescence properties of PSi/Ag were studied by SEM, XRD and photoluminescence spectroscopy. SEM analysis showed that the shape and size of Ag nanostructures significantly depend on the deposition time and concentration. It was found that spherical nanoparticles and thin Ag dendrites were obtained in short deposition times at 1 and 5 mM AgNO3 concentrations, whereas, Ag complex dendrite nanostructures formed in long deposition times. It was also found that only micro-sized Ag particles were formed at 10 mM. XRD results revealed that the degree of crystallization increases with increasing concentration. Photoluminescence analysis showed that the deposition time and concentration of AgNO3 remarkably affect the PL intensity of PSi/Ag samples. We determined a PL enhancement of similar to 2.7 for the PSi/Ag deposited at 120 s for 1 mM AgNO3. The improved PL intensity of PSi/Ag nanostructures can be explained by the combination of quantum confinement and surface states. PL analyses also indicated that with increasing deposition time and AgNO3 concentrations, the PL intensity of PSi/Ag structures significantly decreases due to the auto-extinction phenomenon.