Metal oxide nanowires as building blocks for light detectors, gas sensors and biosensors

Metal oxide nanowires are promising structures for the development of novel electronic and optoelectronic devices. In this work, we describe the synthesis of ZnO and CuO nanowires by vapor phase transport and Cu oxidation, respectively. After removal from the substrate, the nanowires are deposited on pairs of conductive electrodes previously evaporated on SiO2/Si substrates by dielectrophoresis. Al-doped ZnO (AZO) electrodes present good stability during the process and enable the fabrication of ultraviolet photoconductors and sensors along with ZnO nanowires. On the other hand, the deposition of CuO on AZO electrodes yields rectifying behavior related to the p-type conduction in CuO and the formation a diode-to-diode structure with the n-type electrodes. In contrast to ZnO photoconductors, these structures present optical response under illumination with visible and near-infrared light and short turn-on and recovery times.