Growth and properties of well-aligned ZnO hexagonal cones prepared by carbonthermal reaction

Well-aligned ZnO double-cones were successfully synthesized on Si (1 0 0) substrates by carbonthermal reaction. The double-cone consists of a reverse-cone and a bottom-cone connected by a tenuous neck. Scanning electron microscopy, X-ray diffraction, Raman spectroscopy and low temperature photoluminescence measurements were employed to study crystal structure and optical properties of the cones. It is shown that the double-cones have hexagonal crystal structure, uniform sizes and high crystal quality. A growth mechanism was proposed to understand the formation of this novel structure, which involves the variation of chemical composition of the vapor phase and the temperature gradient in the tube. (C) 2004 Elsevier B.V. All rights reserved.