Photoluminescence study of ZnO nanowires with Zn residue

► Growth of ZnO nanowires by thermal annealing of Zn films is demonstrated. ► Diameter of wires varies between 15 and 100 nm. ► Zn residue in the nanowires is controlled by annealing temperature. ► Photoluminescence (PL) and PL Excitation are dependent on fraction of Zn.