GaN-based core-shell nanowires sputtered with Pd target and their annealing characteristics

We have prepared GaN-cored heteronanowires by sputtering with the palladium (Pd) target, subsequently investigating the effects of thermal annealing. The surface of heteronanowires became rough by the thermal annealing, being attributed to the agglomeration of the shell layers into the cluster-like structures. X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction coincidentally indicated that the shell layer comprised the Ga2Pd5 phase. From Gaussian deconvolution studies, we observed that photoluminescence (PL) spectra consisted of red, green, and ultraviolet (UV) emission bands, regardless of shell-coating and subsequent thermal annealing. The integrated PL intensities of red, green, and UV emissions have been changed by the shell-coating and thermal annealing, presumably being associated with the surface-coverage by the shell layer.