Growth mechanism and characterization of zinc oxide hexagonal columns

We report on the growth mechanism, structure, and luminescence properties of ZnO hexagonal columns grown from Zn vapor and air plasma. Single-crystal ZnO columns grow in the [0001] direction through repeated nucleation and growth of epitaxial hexagonal pyramids on the c-planes. Homoepitaxial nucleation of three-dimensional ZnO pyramids is most likely due to the Ehrlich-Schwoebel effect. This mechanism produces columns that are a few hundred nanometers in diameter and up to 2 mum in length. Convergent beam electron diffraction shows that the columns grow with Zn polarity in the [0001] direction. Cathodoluminescence and photoluminescence measurements show near-bandedge emission (3.29 eV) with no emission associated with oxygen vacancies at 2.5 eV. (C) 2003 American Institute of Physics.