Synthesis and electrical characterization of vertically-aligned ZnO-CuO hybrid nanowire p-n junctions

In order to form nanowire (NW)-based p-n junctions, vertically-aligned ZnO-CuO hybrid NW arrays were synthesized by a two-step thermal chemical vapor deposition process. The diameter of parallel-connected ZnO and CuO NWs were estimated to be 146 ± 12 nm and 55 ± 11 nm, respectively, as observed by scanning electron microscopy. Chemical and structural characterizations of ZnO-CuO hybrid NW arrays were performed using X-ray photoelectron spectroscopy and X-ray diffraction, resulting in the formation of high-quality hexagonal ZnO and monoclinic CuO NWs. The temperature dependence of I-V curves and impedance spectra suggested that clear rectifying behavior related with thermionic emission of carriers and the presence of an electrical potential barrier between the ZnO and CuO NWs.