0000000000013042
AUTHOR
Vincent Sallet
Structural characterization of one-dimensional ZnO-based nanostructures grown by MOCVD
Various one-dimensional (1D) ZnO-based nanostructures, including ZnO nano-wires (NWs) grown using vapour-liquid-solid (VLS) process, ZnO/ZnSe core/shell, nitrogen-doped ZnO and ZnMgO NWs were grown by metalorganic chemical vapour deposition (MOCVD). Transmission electron microscopy (TEM) analysis is presented. For all the samples, a high crystalline quality is observed. Some features are emphasized such as the gold contamination of ZnO wires grown under the metal droplets in the VLS process. It is concluded that MOCVD is a suitable technique for the realization of original ZnO nanodevices.
Effect of Growth Temperature on the Structural and Morphological Properties of MgCdO Thin Films Grown by Metal Organic Chemical Vapor Deposition
II-VI oxides ternary alloys have attracted considerable interest of the scientific community due to the possibility of modulating their interesting optoelectronic properties. Despite this interest, MgCdO has been poorly studied. In this work, by using the metal organic chemical vapor deposition method at low pressure, we have analyzed the synthesis of thin films of this alloy. Thus, for a fixed metal-organic precursors content, a change from Mg1-xCdxO (Mg-rich phase) to Cd1-xMgxO (Cd-rich phase) has been induced when decreasing the growth temperature. The temperature range where both phases coexist has been particularly analyzed. Using X-ray diffraction analysis and scanning electron micros…
Non radiative recombination centers in ZnO nanorods
ABSTRACTNowadays, the nature of the non radiative recombination centres in ZnO is a matter of controversy; they have been related to extended defects, zinc vacancy complexes, and surface defects, among other possible candidates. We present herein the optical characterization of catalyst free ZnO nanorods grown by atmospheric MOCVD by microRaman and cathodoluminescence spectroscopies. The correlation between the defect related Raman modes and the cathodoluminescence emission along the nanorods permits to establish a relation between the non radiative recombination centers and the defects responsible for the local Raman modes, which have been related to Zn interstitial complexes.
Some aspects of the MOCVD growth of ZnO on sapphire using tert-butanol
The growth of ZnO on (0001) sapphire substrates using metalorganic chemical vapor deposition is reported. Diethylzinc and tertiarybutanol were used, respectively, as zinc and oxygen sources. Growth conditions are detailed such as the substrate temperature and the precursors partial pressures. The influence of the cleanness state of the MOCVD silica reactor is emphasized, since it modifies both layer quality and crystalline orientation, and since it also affects growth process steps like sapphire thermal treatment and buffer layer deposition. ZnO epitaxial layers are characterised by scanning electron microscopy (SEM) to assess the surface orientation and morphology, X-ray diffraction (XRD) …
Morphology of ZnO grown by MOCVD on sapphire substrates
A quantitative roughness and microstructural analysis of ZnO grown on sapphire by atmospheric metalorganic chemical vapor deposition (MOCVD) is presented. In order to investigate the influence of the substrate on the morphology, different sapphire orientations have been employed. Scanning force microscopy data have been analyzed for a variety of thicknesses to elucidate, if possible, the growth mechanisms involved in the growth process. Our study reveals significant differences between morphologies depending on whether the substrate surface exhibits steps (misoriented a-, c- and r-planes) or not (m-plane); however, no major differences on the calculated roughness coefficients have been foun…
Morphology transitions in ZnO nanorods grown by MOCVD
Morphology transitions (nanorods–nanowalls and nanorods–nanotubes-layer) were induced in the growth of ZnO nanostructures by metal organic chemical vapor deposition (MOCVD) on c-sapphire, using helium as carrier gas, and dimethylzinc–triethylamine and nitrous oxide as zinc and oxygen sources, respectively. A systematic study of the influence of the VI/II ratio and precursor flow-rates on the morphology of ZnO nanorod arrays has been carried out, taking advantage of the ability of MOCVD to individually control the precursor partial pressures. Growth mechanisms are discussed to understand the evolution of the nanostructures morphology for different growth conditions. In particular, the influe…
Assessment of the out-plane and in-plane ordering of high quality ZnO nanorods by X-ray multiple diffraction
Abstract ZnO nanorods grown on buffered and non buffered sapphire substrates have been investigated by X-ray multiple diffraction using Renninger scans of the ZnO(0001) and ZnO(0003) forbidden reflections. In this technique the diffracted X-ray beam is simultaneously diffracted by several sets of planes, providing information on the broadening in different directions, as well as from nanorods, and from the layer on which they grow. The intensities and angular widths of peaks obtained by azimuthal and omega scans have been analyzed, making a direct comparison with conventional measurements of the full width at half-maximum of symmetric and asymmetric reflections. The analysis leads to establ…