Hydrothermal fabrication and optical properties of wheatear-like ZnO array

A simple secondary process under hydrothermal conditions was employed to fabricate the wheatear-like ZnO array. The microstructure, morphology and photoluminescence property of the as-prepared products were characterized by x-ray diffractometer (XRD), high-resolution transmission electron microscopy (TEM), field emission environment scanning electron microscope (SEM) and photoluminescence spectrum (PL) respectively. The experimental results indicate that the kernel-like nanorods from wheatear-like structure, hexagonal wurtzite monocrystal, are epitaxial on the nonpolar planes of needle-like ZnO. A possible growth mechanism of the wheatear-like ZnO array related to the secondary hydrothermal process is proposed. The PL spectrum of the wheatear-like ZnO array shows a strong ultraviolet emission at 380nm and a relative inferior yellow emission at 557nm. Compared with the ultraviolet emission of the needle-like ZnO array, the red shift of 2nm for the ultraviolet peak of the wheatear-like product is obvious, which results from its energy gap narrowing.