Optical properties of highly luminescent zinc oxide tetrapod powders

Abstract

Zinc oxide tetrapod powders with high luminescent characteristics have been grown by simple evaporation and direct oxidation of zinc. Their structural and optical properties have been studied by transmission electron microscopy and by cathodoluminescence. The legs of the tetrapods have a pure hexagonal structure and form an arrowhead joint at the center. The tetrapod legs exhibit strong band edge and weak green luminescence. Monochromatic cathodoluminescence images show that the band-edge emission originates from the bulk of the legs, while the green emission emanates from the surface, indicative of it being related to oxygen vacancies. Low temperature cathodoluminescence shows a direct correlation of near-band-edge emission with specific sites within the structure.