Byunggu Kim

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.

Facile Synthesis and Enhanced Ultraviolet Emission of ZnO Nanorods Prepared by Vapor-Confined Face-to-Face Annealing

In this study, we report a novel regrowth method of sol-gel-prepared ZnO films using a vapor-confined face-to-face annealing (VC-FTFA) technique in which mica was inserted between two films, followed by annealing with the FTFA method. The ZnO nanorods are regrown when zinc acetate dihydrate and zinc chloride (ZnCl2) are used as the solvent, because these generate ZnCl2 vapor. The near-band-edge emission intensity of the ZnO nanorods was enhanced through the VC-FTFA method, increasing significantly by a factor of 56 compared to that of ZnO films annealed in open air at 700 °C. Our method may provide a route toward the facile fabrication of ZnO 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.