GaN nanowires sputtered with Ag shell layers

We have demonstrated the fabrication of GaN-core/Ag shell nanowires and investigated their annealing effects. Scanning electron microscopy has revealed that the thermal annealing facilitated the surface-roughening of the heteronanowires. TEM investigations indicated that the thermal annealing has changed the shell morphology from continuous Ag layer to the discrete Au nanoparticles or islands. X-ray diffraction suggested that the thermal annealing has enhanced the crystallinity of Ag shell. Photoluminescence measurements revealed that the Ag-sputtering has induced an UV peak, in addition to the GaN-associated emission peaks. Thermal annealing has further changing the overall shape of the PL spectrum and we have discussed the possible emission mechanisms. (C) 2009 Elsevier B.V. All rights reserved.