Toward laser emission of epitaxial nanorod arrays of ZnO grown by electrodeposition

Arrays of epitaxial, vertically oriented nanorods of ZnO are grown at low temperature $(80°\mathrm{C})$ on the (0002) plane of GaN single crystals by electrodeposition in an aqueous solution. The freestanding nanocolumns are prepared by a template-free method based on simple solution chemistry. At room temperature, the nanorods present an amplified ultraviolet emission centered at $381\mathrm{nm}$ with an excitation threshold at $4.4\mathrm{MW}{\mathrm{cm}}^{-2}$ . The amplified emission of the ZnO columns is dominated by the radiative recombination of excitons.