A novel metal-insulator heterostructure made of twinned Ga2O3 nanowires embedding discrete gold particles along the twin boundary was formed through a reaction between gold, gallium, and silica at 800 degrees C during simple thermal annealing. The Au-in-Ga2O3 peapods spontaneously crystallized under phase separation induced by the formation of twin boundaries. The nanostructures were analyzed by field emission scanning (FESEM) and transmission electron microscopes (FETEM), and their photoresponse was investigated using a double-frequency Nd:YAG laser with a wavelength of 532 nm on a designed single-nanowire device. The surface plasmon resonance (SPR) effects of embedded Au nanoparticles are proposed to be responsible for the remarkable photoresponse of these novel structures.

Functional 1D metal oxides have attracted much attention because of their unique applications in electronic, optoelectronic, and spintronic devices.[1] For semiconducting oxide nanowires (NWs) (e.g., ZnO, In 2 O 3 , and SnO 2 NWs), field-effect transistors and light-emitting diodes have been demonstrated. [2] Metallic oxide nanoscale materials, such as nanoscale RuO 2 , can be good candidates as interconnects in electronic applications.[3] RuO 2 nanomaterials have been produced by chemical vapor deposition (CVD) and through chemical reaction. [3b,4] Recently, RuO 2 NWs have been synthesized using pure Ru as metal target under different flux ratios of O 2 /Ar in a reactive sputtering system.[5]For core/shell structures, extensive research has been carried out on systems such as Ge/Si, [6] GaN/AlN/AlGaN, [7] Ta 2 O 5 /SiO 2 , [8] and Fe 3 O 4 /MgO. [9] The Ge/Si core/shell NW, for example, is a high-performance field-effect transistor because of the reduced carrier scattering. GaN/AlN/AlGaN core/shell NWs exhibit a high electron mobility. For the SiO 2 / Ta 2 O 5 core/shell structure, the axial confinement of light propagation can effectively reduce the energy loss owing to the difference in refractive index between Ta 2 O 5 and SiO 2 . Following the successful synthesis of a RuO 2 /TiO 2 core/ shell structure by reactive sputtering, [10] we mainly focus on the investigation of the physical properties of the RuO 2 NWs in the present study. The detailed epitaxial relationship and electronic structures of the RuO 2 /TiO 2 core/shell structure synthesized by reactive sputtering are investigated. The mechanical, optical, and electrical properties and photocatalyst response to UV irradiation are characterized. Our results suggest the potential application of the NWs as interconnects and optoelectronic devices. Figure 1a shows a scanning electron microscopy (SEM) image of RuO 2 NWs synthesized by the reactive sputtering approach at a synthesis temperature of 450°C for 3 h, and indicates a high density of uniform RuO 2 NWs more than several micrometers long. In addition, most of the RuO 2 NWs have a square cross section, as shown in the inset of Figure 1a. The corresponding X-ray diffraction (XRD) spectrum, shown in Figure 1b, confirms that the phase of the NWs is rutile-structured RuO 2 with lattice-constant values of a = 0.45 nm and c = 0.31 nm. After deposition of a thin TiO 2 layer via reactive sputtering deposition, the morphology of these NWs remains unchanged, but the sizes increase, as shown in Figure 1c. The corresponding XRD spectrum of the NWs is shown in Figure

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Gold-peapodded Ga(2)O(3) nanowires were fabricated successfully in a well-controlled manner by thermal annealing of core-shell gold-Ga(2)O(3) nanowires. During the heating process, the core gold nanowires were broken up into chains of nanoparticles at sufficiently high temperature by the mechanism of Rayleigh instability. In addition, the size, shape, and interspacing between the particles can be manipulated by varying the annealing time and/or the forming gas. The plasmonic behaviors of these nanostructures are investigated by optical spectroscopy. A single nanowire optical device was designed, and its photonic characteristics were investigated. A remarkably high on/off photocurrent ratio in response to a 532 nm Nd:YAG laser light was found. As the size of the particle (pea) increases, the corresponding spectra are red-shifted. In addition, morphological changes of the peas lead to a distinct spectral response. The results may usher in the diverse applications in optoelectronics and biosensing devices with peapod nanostructures.