Hydrothermal synthesis of well-aligned ZnO nanorod arrays on Silicon

Zinc oxide (ZnO) nanorod arrays were fabricated on ZnO:Al seeded Si substrates with various reaction temperatures using a low temperature hydrothermal method. The morphology and structure of ZnO nanorod arrays were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). It reveals that the ZnO nanorods grow vertically on Si surface with (002) preferential orientation. The transmittance spectra show the ZnO nanorod arrays fabricated at low temperatures have high transmittance in the visible region and decrease with reaction temperature increasing. Moreover, the same trend was also observed in the reflectance spectra of the ZnO nanorod arrays. The optimal reaction temperature is of 120 degrees C for ZnO nanorod arrays with high transmittance (similar to 80%) and low reflectance (similar to 10%) in the visible region. The superior optical properties make ZnO nanorod arrays promising for applications as transparent electrodes.