Youngbin Park

Hydrothermally grown boron-doped ZnO nanorods for various applications: Structural, optical, and electrical properties

The structural, optical, and electrical properties of ZnO and BZO nanorods were investigated using fieldemission scanning electron microscopy, x-ray diffraction (XRD), photoluminescence (PL), and van der Pauw Hall-effect measurements. All the nanorods had grown well on the ZnO seed layers and were hexagonal. The BZO nanorods were shorter than the undoped ZnO nanorods, and the BZO nanorods grew shorter with increasing concentration of B to 2.0 at. % while the average length of the nanorods doped with 2.5 at. % B increased from 1620 to 1830 nm. The XRD patterns suggest that the amount of residual stress in the nanorods decreased with increasing concentration of B in the nanorods. The PL spectra showed near-bandedge and deep-level emissions, and B doping also varied the PL properties of the ZnO nanorods. The Halleffect data suggest that B doping also varied the electrical properties such as the carrier concentration, mobility, and resistivity of the ZnO nanorods.

A novel regrowth mechanism and enhanced optical properties of Mg0.25Zn0.75O nanorods subjected to vapor-confined face-to-face annealing

Although the sol–gel spin-coating method is usually a technique for depositing thin films, here, we report on the sol–gel fabrication of one-dimensional Mg0.25Zn0.75O nanorods through the use of vapor-confined face-to-face annealing (VC-FTFA), in which mica is inserted between two films before annealing using the FTFA method. Mg0.25Zn0.75O nanorods are regrown when magnesium chloride hexahydrate is used as the solvent, because ZnCl2 and MgCl2 vapors are generated under these conditions. The near-band-edge emission intensity of the Mg0.25Zn0.75O nanorods is enhanced by VC-FTFA by a factor of 37 compared to that of the films annealed in open air at 700 °C. Our method may provide a route for the facile fabrication of Mg0.25Zn0.75O nanorods.

A novel regrowth method to simply prepare Li-doped ZnO nanorods and improve their photoluminescence properties

In this study, we report the fabrication of sol–gel prepared ZnO nanorods through the use of vapor-confined face-to-face annealing (VC-FTFA) in which mica was inserted between two films, followed by annealing using the FTFA method. LZO nanorods are regrown when lithium chloride is used as the solvent because ZnCl2 and LiCl vapors are generated. The near-band-edge emission intensity of the LZO nanorods is enhanced through annealing using the VC-FTFA method and is increased by a factor of 6 compared to that of LZO thin films annealed in open air at 600 °C. Our method may provide a route toward the facile fabrication of ZnO nanorods.

Effects of Precursor Concentration and Current on Properties of ZnO Nanorod Grown by Electrodeposition Method

ZnO nanorods have been deposited on ITO glass by electrodeposition method. The optimization of two process parameters (precursor concentration and current) has been studied in order to control the orientation, morphology, and optical property of the ZnO nanorods. The structural and optical properties of ZnO nanorods were systematically investigated by using field-emission scanning electron microscopy, X-ray diffractometer, and photoluminescence. Commonly, the results show that ZnO nanorods with a hexagonal form and wurtzite crystal structure have a c-axis orientation and higher intensity for the ZnO (002) diffraction peaks. Both high precursor concentration and high electrodeposition current cause the increase in nanorods diameter and coverage ratio. ZnO nanorods show a strong UV (3.28 eV) and a weak visible (1.9 ~ 2.4 eV) bands.

Effects of Growth Temperature and Time on Properties of ZnO Nanostructures Grown by Electrodeposition Method

The electrodeposition of ZnO nanorods was performed on ITO glass. The optimization of two process parameters (solution temperature and growth time) has been studied in order to control the orientation, morphology, density, and growth rate of ZnO nanorods. The structural and optical properties of ZnO nanorods were systematically investigated by using field-emission scanning electron microscopy, X-ray diffractometer, and photoluminescence. Commonly, the results of the structural property show that hexagonal ZnO nanorods with wurtzite crystal structures have a c-axis orientation, and higher intensity for the ZnO (002) diffraction peaks. Furthermore, the nanorods length increased with increasing both the solution temperature and the growth time. The results of the optical property show a strong UV (3.28 eV) peaks and a weak visible (1.9~2.4 eV) bands, the intensity of UV peaks was increased with increasing both the solution temperature and the growth time. Especially, the UV peak for growth of nanorods at 75oC blue-shift than different temperatures.