ZnO/Al2O3 core-shell nanorod arrays: growth, structural characterization, and luminescent properties

We report an aqueous chemical method to fabricate well-aligned ZnO/Al2O3 nanocrystal (NC) core-shell nanorod arrays (NRAs). Structural characterization showed that the shell layers are composed of alpha-Al2O3 nanocrystals. Photoluminescence measurements showed the enhancement of near-band-edge (NBE) emission of ZnO NRAs due to the presence of Al2O3 NC shells. The Al2O3 NC shell layer resulting in the flat-band effect near the ZnO surface leads to a stronger overlap of the wavefunctions of electrons and holes in the ZnO core, further enhancing the NBE emission. This approach should be very useful in designing many other core-shell NRAs for creating varieties of high-efficiency optoelectronic devices.