Schottky junction study for electrodeposited ZnO thin films and nanowires

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.