Synthesis of Au in Ga2O3 peapodded nanorods and their photoluminescence properties

Gold (Au) in gallium oxide (Ga2O3) peapodded one-dimensional (1D) nanostructures were synthesized by thermal evaporation of GaN powders on Si (1 0 0) substrates coated with Au thin films followed by annealing. At the initial stages of annealing, Au formed a continuous linear core located along the long axis of each Ga2O3 nanorod. The morphology of the Au core changed from a continuous line to a discrete line, and then to a droplet-like chain, finally evolving into a peapod in which crystalline Au nanoparticles were encapsulated in crystalline Ga2O3 with increasing annealing temperature. The Ga2O3 nanorods with the Au core showed an emission band at ∼410 nm in the violet region. The violet emission intensity increased rapidly with increasing annealing temperature. The intensity of emission from the Au in Ga2O3 pepodded nanorods (annealed at 800 °C) was approximately six times higher than that of the emission from the Au-core/Ga2O3-shell nanorods with a continuous linear shaped-Au core (annealed at 600 °C). This intense violet emission from the core-shell nanorods annealed at 800 °C might have originated mainly from the surface plasmon resonance (SPR) of Au-peapods whereas the less intense violet emission from the core-shell nanorods annealed at 600 or 700 °C might have originated mainly from the band-to-band transition of the Ga2O3 shells.

► Gold in Ga2O3 peapodded nanorods were synthesized.
► The morphology of the Au core depended on the annealing temperature strongly.
► The gold in Ga2O3 peapodded nanorods showed the strongest violet emission.
► The ultraintense violet emission might be due to the surface.