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۱Optical Properties of ZnO Nanowires and Nanorods Synthesized by Two Step Oxidation Process
نویسنده(ها): ، ،
اطلاعات انتشار: Journal of Ultrafine Grained and Nanostructured Materials، چهل و ششم،شماره۱، ۲۰۱۳، سال
تعداد صفحات: ۶
ZnO nanowires with a diameter of 70 nm and nanorods with a diameter in the range of 100–150 nm and two micrometer in length were grown on glass substrates by resistive evaporation method and applying a two step oxidation process at low temperatures, without using any catalyst, template or buffer layer. XRD pattern of these nanostructures indicated a good crystallinity property with wurtzite hexagonal structure. Photoluminescence measurement revealed three band emissions; one sharp strong peak in the UV region and two weaker peaks in the visible region, indicate good optical properties of nanorods synthesized by this method. Heat treatment in oxygen–rich atmosphere results to decrease of deep–level emission intensity in the PL spectra. The relatively high intensity of UV emission implies that this approach is a simple and promising method for fabricating ZnO nanorods in order to be used in optoelectronic devices especially in the UV range of the spectrum.

۲The effect of annealing time and temperature on morphology and optical properties of ZnO nanostructures grown by a self–assembly method
نویسنده(ها): ، ،
اطلاعات انتشار: Scientia Iranica، بيستم،شماره۳، ۲۰۱۳، سال
تعداد صفحات: ۱۰
Synthesis of ZnO nanostructures was achieved on glass substrate by the resistive evaporation of metallic zinc granules followed by dry oxidation process at 350, 450 and 550 °C. Characterization of the products with FESEM and TEM revealed that the structures obtained at 450 °C are mostly nanorods with diameters between 40 and 105 nm and lengths from 1 to 5 μm. One dimensional ZnO nanostructures such as ultra thin nanobelts, nanowires and nanorods were successfully synthesized at 550 °C, with lengths up to several micrometers. XRD patterns indicated that the structures are crystalline and that ZnO nanostructures grown at 550 °C are fully oxidized and are crystalline with wurtzite hexagonal structure. PL measurements were carried out at room temperature and they revealed that there are three band emissions; one sharp strong peak in the UV region and two weaker peaks in the visible region. A strong UV emission was observed in the spectra of the ZnO nanorods and nanowires which confirms the good optical properties of products. The PL spectra also exhibited a considerable shift toward the shorter wavelength in the UV region. It is clear that after the second annealing step photoluminescence of the 1D nanostructures, fabricated at 550 °C, have improved, especially in the UV region.
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