Low temperature synthesis and characterization of MgO/ZnO composite nanowire arrays.

Large scale dendritic MgO/ZnO composite nanowire arrays have been successfully synthesized on Si substrates using a two-step sequential hydrothermal synthesis at low temperature for the first time. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), and x-ray photoelectron spectroscopy (XPS) were systematically carried out to confirm and elaborate the potentially localized Mg surface alloying process into the ZnO nanowire arrays. Both room temperature and low temperature (40 K) photoluminescence results revealed an enhanced and blue-shifted near-band-edge (NBE) ultraviolet (UV) emission for the MgO/ZnO nanowires compared to those of the pure ZnO nanowire arrays, indicating the success of Mg alloying into ZnO nanowires. This enhancement might be due to the 155 degrees C hydrothermal process and the amorphous MgO layer in the MgO/ZnO nanowires. The specific template of densely packed ZnO nanowire arrays was suggested to be instrumental in enabling this type of MgO/ZnO composite nanowire growth.