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International audience; Wereport in this work the fabrication of ZnO nanowires and nano-pillars by electrodeposition using three types of micro- and nano-structured templates. First, ZnO nanowires were synthesized in a nanoporous polycarbonate template and their morphology and monocrystalline structure were checked by conventional transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) techniques. The optical properties of the monocrystalline ZnO nanowires were also studied by measuring the photo-fluorescence spectra of the sample. Then, the micro-structured template was made by optical lithography and the electrodeposited ZnO micro-rods were analysed by scanning electron microscopy (SEM) imaging and X-ray diffraction (XRD). Finally, UV-nanoimprint templates were used for the fabrication of regular ZnO nano-pillar array. SEM images showed quite homogenous ZnO nano-pillar array on which the collective I–V characteristic has been carried out in order to determine the nature of the Au/ZnO contact. SEM images also revealed an effect of size increase of the ZnO microrods and nano-pillars with respect to that of the PMMA template. XRD patterns showed the hexagonal Wurtzite crystalline structure with cell parameters slightly larger than the literature ones.

ZnO thin films and well-aligned nanowire arrays have been synthesized via electrochemical deposition method, a low temperature and low cost synthesis method. For the ZnO nanowires growth, the electrodeposition consists of two steps: the ZnO buffer layer was firstly deposited on the substrate using galvanostatic method at room temperature following by the ZnO nanowires growth under potentiostatic method at 80 °C. This second step has also used for the ZnO thin films growth directly on substrate. The morphological and microstructural properties of the as-deposited ZnO have been characterized using scanning and transmission electron microscopy (SEM and TEM), X-ray diffraction (XRD), as well as photoluminescence spectroscopy (PL). The electrical transport of the ZnO thin films and nanowire arrays have been studied at room temperature both in the symmetrical Al/ZnO/Al electrode configuration guarantying a good Ohmic contact and in the asymmetrical Al/ZnO/Au electrode configuration demonstrating a typical Schottky contact at the interface ZnO/Au. The feature parameters such as the series resistance, the Schottky barrier height, and the ideality factor, have been systematically analyzed. Comparing the diode parameters between thin films and nanowire arrays, we deduced that about 1/3 of the ZnO nanowires come into effective contact with the top Al electrode.

We report here the systematic study of well controlled ZnO nanowire arrays grown via two different chemical ways: electrodeposition and hydrothermal method, which are frequently used for low cost synthesis of ZnO nanowire arrays. Both methods consist of two elaboration steps: a seed layer ZnO was first deposited on the substrate and then the growth of the ZnO nanowire arrays on the seed layer was performed. Scanning electron microscopy observations show a similar morphology, while x-ray diffraction (XRD) and Raman spectra revealed a preferred orientation of ZnO nanowires towards the c-axis. High resolution transmission electron microscopy analysis showed excellent monocrystallinity of the nanowire. A p-n junction structure based on above two kinds of nanowire arrays with a p-CuSCN layer was fabricated and their photoluminescence (PL) and conductance were measured in comparison. PL measurements demonstrated a higher defects concentration in ZnO nanowires obtained by hydrothermal method which leads to a very high current in the corresponding p-n junction with the p-CuSCN layer. This property is very important in prospective to future applications such as photovoltaic cell, nanogenerator, or gas sensor.