Article

Well-aligned ZnO microprism arrays with umbrella-like tips: Low-temperature preparation, structure and UV photoluminescence improvement

State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Changning Road, Shanghai 200050, People's Republic of China
Physica E Low-dimensional Systems and Nanostructures (Impact Factor: 1.86). 08/2008; 40(9):2931-2936. DOI: 10.1016/j.physe.2008.02.012

ABSTRACT Catalyst-free, low-temperature (430 °C), high-density, well-aligned, single-crystalline zinc oxide (ZnO) microprism (ZMP) arrays have been synthesized over the entire c-ZnO/poly-Zn-coated Si substrates by simple thermal evaporation of Zn powder. Specially, the microprisms obtained possess hexagonal umbrella-like tips on which vertical thin ZnO nanowires grow. The growth mechanism of a three-stage thermodynamic process was discussed. Photoluminescence spectra show a strong ultraviolet (UV) emission enhancement of the ZMPs after H+ (hydrogen ions) implantation. This kind of special ZnO microstructure may find potential applications in field emission, UV laser emission devices, multifunctional microdevices and highly integrated multichannel nano-optoelectronic devices.

0 Followers
 · 
58 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Distinctive zinc oxide (ZnO) nanocrystals were synthesized on the surface of Zn probes using a counter-flow flame medium formed by methane/acetylene and oxygen-enriched air streams. The source material, a zinc wire with a purity of ∼99.99% and diameter of 1 mm, was introduced through a sleeve into the oxygen rich region of the flame. The position of the probe/sleeve was varied within the flame medium resulting in growth variation of ZnO nanocrystals on the surface of the probe. The shape and structural parameters of the grown crystals strongly depend on the flame position. Structural variations of the synthesized crystals include single-crystalline ZnO nanorods and microprisms (ZMPs) (the ZMPs have less than a few micrometers in length and several hundred nanometers in cross section) with a large number of facets and complex axial symmetry with a nanorod protruding from their tips. The protruding rods are less than 100 nm in diameter and lengths are less than 1 μm. The protruding nanorods can be elongated several times by increasing the residence time of the probe/sleeve inside the oxygen-rich flame or by varying the flame position. At different flame heights, nanorods having higher length-to-diameter aspect-ratio can be synthesized. A lattice spacing of ∼0.26 nm was measured for the synthesized nanorods, which can be closely correlated with the (0 0 2) interplanar spacing of hexagonal ZnO (Wurtzite) cells. The synthesized nanostructures were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high resolution TEM (HR-TEM), X-ray energy dispersive spectroscopy (EDS), and selected area electron diffraction pattern (SAED). The growth mechanism of the ZnO nanostructures is discussed.
    Materials Science and Engineering B 02/2013; 178(2):127–134. DOI:10.1016/j.mseb.2012.10.031 · 2.12 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Wet oxidation can be used to produce high quality zinc oxide (ZnO) nanostructures at moderately high temperatures with low requirements of equipment and experimental conditions. Zn precursor films were prepared by magnetron sputtering and controlled ZnO nanostructures were produced by oxidation of the Zn precursor films in wet O2. The growth mechanism of the ZnO nanowires and nanobelts in wet oxidation was discussed based on the experimental results. Silver and nitrogen doping were realized in the wet oxidation process, with different techniques. The structural and optical properties of the ZnO nanostructures were characterized by means of scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and photoluminescence (PL) measurements to understand the growth process of ZnO in wet oxidation. The production of ZnO porous films by wet oxidation process is also presented.
    Progress in Natural Science 04/2011; 21(2):81–96. DOI:10.1016/S1002-0071(12)60041-0 · 1.14 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A detailed comparative study of zinc oxide (ZnO) nanorods (NRs) grown by thermal annealing method in air, oxygen and water loaded oxygen environments was carried out. The number density, diameter and length of the NRs were studied as a function of annealing temperature and duration of anneal in all the three environments. Scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and photo-luminescence spectroscopy (PL) were used for the characterizations. The growth in water loaded oxygen environment was best and led to a very high density, good aspect ratio NRs of very good optical quality as compared to the other two environments. The environment and annealing temperature critically influenced the density and aspect ratio whereas the duration of annealing affected mainly the aspect ratio of NRs. It was also found that water vapor increased the density of NRs growth by an order. It has been proposed that the growth of NRs takes place due to the relaxation of stress accumulated in oxide film during the process of oxidation and annealing.
    Journal of Alloys and Compounds 10/2014; 611:117–124. DOI:10.1016/j.jallcom.2014.05.057 · 2.73 Impact Factor