Self-assembled formation of ZnO hexagonal micropyramids with high luminescence efficiency

The authors have found the self-assembled formation of ZnO hexagonal micropyramids after the growth of a sufficiently thick ZnO layer on a (0001) Al2O3 substrate by rf-magnetron sputtering deposition. It was confirmed by scanning electron microscopy that the orientations of the micropyramids are well arranged. The reflection and photoluminescence spectra at 10 K demonstrate that optical properties of the total growth layer are of high quality. The noticeable discovery with the use of cathodoluminescence spectroscopy is that the luminescence intensity of the micropyramids is 30 times stronger than that of the underlying layer; namely, strong enhancement of luminescence is realized in the self-assembled micropyramids. (c) 2007 American Institute of Physics.