Synthesis of Au in Ga2O3 peapodded nanorods and their photoluminescence properties

Abstract

Gold (Au) in gallium oxide (Ga2O3) peapodded one-dimensional (1D) nanostructures were synthesized by thermal evaporation of GaN powders on Si (100) 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 ∼410nm 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.