Growth mechanism and characterization of ZnO microbelts and self-assembled microcombs

We report the structural characterization and growth mechanism of ZnO microbelts and microcombs synthesized by direct thermal evaporation and post-oxidation of the pure Zn powders. The synthesized ZnO products are hexagonal wurtzite structured and in the range of micrometer size. The formation of the microcombs follows a two-step process: the comb-stems are formed by a fast vapor–solid (VS) growth along [112¯0] direction, and the comb-teeth are grown by a subsequent faceted epitaxial growth parallel to the (0001) polar surface. A novel structure of enantiomorphous twin-microcombs is also detected in the synthesized products. Photoluminescence (PL) spectrum shows that the prepared products are green emission, centered at about 507 nm.