Yazar "Yilmaz, Ibrahim" seçeneğine göre listele

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    Generation of Gallium Nitride Nano Particles in Organic Solution Using Pulse Laser Ablation
    (Turgut Ozal Univ, 2012) Demirel, Abdulmelik; Oztas, Tugba; Ortac, Bulend; Yilmaz, Ibrahim
    We report the synthesis of colloidal GaN nanoparticles in organic solution through nanosecond pulsed laser ablation of GaN powder. The size, the structural, the optical and the chemical characteristics of GaN nanoparticles demonstrate that the colloidal GaN nanoparticles in ethanol were synthesized with spherical shape within 6-25 nm particle size distributions. Optical absorption of colloidal nanosolution presents strong absorption edge tailoring from 350 nm to 200 nm.
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    Long- range ordered vertical III- nitride nanocylinder arrays via plasma- assisted atomic layer deposition
    (Royal Soc Chemistry, 2018) Haider, Ali; Deminskyi, Petro; Yilmaz, Mehmet; Elmabruk, Kholoud; Yilmaz, Ibrahim; Biyikli, Necmi
    In this work, we demonstrate vertical GaN, AlN, and InN hollow nano-cylindrical arrays (HNCs) grown on Si substrates using anodized aluminum oxide (AAO) membrane templated low-temperature plasma-assisted atomic layer deposition (PA-ALD). III-Nitride HNCs have been characterized for their structural, chemical, surface, and optical properties. The material properties of nanostructured III-nitride materials have been compared with the thin-film counterparts which were also grown using PA-ALD. Our results revealed that long-range ordered arrays of III nitride HNCs were successfully integrated on Si substrates and possess hexagonal polycrystalline wurtzite crystalline structure. Such long-range ordered wafer-scale III-nitride nanostructures might be potentially used in piezotronic sensing, energy harvesting, resistive memory, flexible and wearable electronics, III-nitride photovoltaics, and (photo)catalysis.
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    Synthesis of blue-shifted luminescent colloidal GaN nanocrystals through femtosecond pulsed laser ablation in organic solution
    (Springer, 2016) Demirel, Abdulmelik; Oztas, Tugba; Kursungoz, Canan; Yilmaz, Ibrahim; Ortac, Bulend
    We demonstrate the synthesis of GaN nanocrystals (NCs) with the sizes of less than the doubled exciton Bohr radius leading quantum confinement effects via a single-step technique. The generation of colloidal GaN nanoparticles (NPs) in organic solution through nanosecond (ns) and femtosecond (fs) pulsed laser ablation (PLA) of GaN powder was carried out. Ns PLA in ethanol and polymer matrix resulted in amorphous GaN-NPs with the size distribution of 12.4 +/- 7.0 and 6.4 +/- 2.3 nm, respectively, whereas fs PLA in ethanol produced colloidal GaN-NCs with spherical shape within 4.2 +/- 1.9 nm particle size distribution. XRD and selected area electron diffraction analysis of the product via fs PLA revealed that GaN-NCs are in wurtzite structure. Moreover, X-ray photoelectron spectroscopy measurements also confirm the presence of GaN nanomaterials. The colloidal GaN-NCs solution exhibits strong blue shift in the absorption spectrum compared to that of the GaN-NPs via ns PLA in ethanol. Furthermore, the photoluminescence emission behavior of fs PLA-generated GaN-NCs in the 295-400 nm wavelength range is observed with a peak position located at 305 nm showing a strong blue shift with respect to the bulk GaN.