Study on the structural and physical properties of ZnO nanowire arrays grown via electrochemical and hydrothermal depositions

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.