ZnO hollow nanosphere (HNS) arrays decorated with Ag nanoparticles (NPs) were fabricated on silicon substrates using self-assembled monolayer polystyrene (PS) nanospheres as the template. The O 2 plasma etching was introduced to manipulate the diameters of the ZnO HNSs. This fabrication method has the advantages of simplicity, large scale production, easy size and shape manipulations, low cost and bio-compatibility. Scanning electron microscopy (SEM) images show that the obtained Ag NP-ZnO HNS hybrid structures are hexagonally arranged, with the uniform size and shape, and the X-ray diffraction (XRD) pattern shows that the ZnO HNS arrays are of high crystal quality and have a dominant orientation of <0001> direction. Resonant Raman scattering spectra reveal the multiphonon A1 (LO) modes of ZnO hollow nanospheres at 574, 1147 and 1725 cm À1 . Enhanced resonant Raman scattering from the Ag NP modified ZnO HNSs was observed, indicating a strong energy coupling effect located at the metal/semiconductor interface. Surface enhanced Raman scattering (SERS) application for the Ag NP decorated ZnO HNS arrays was verified using a Rhodamine 6G (R6G) chromophore as a standard analyte, which is proved to be an effective SERS template for Raman signal detection. SERS substrates with different structures have been compared, and the Ag NP modified ZnO HNS system exhibits superior Raman scattering enhancements induced by the local surface plasmon resonance (LSPR) effect. The SERS mechanism was well explained by theoretical calculation results. This study is helpful to fabricate controllable Ag NP arrays using the ZnO HNS as the supporting structure and to understand the mechanism of bio-sensing enhancements due to the LSPR effect originated from the metal NPs and metal/semiconductor interface.

A correlation between the structural and optical properties of GaN thin films grown in the ͓1120͔ direction has been established using transmission electron microscopy and cathodoluminescence spectroscopy. The GaN films were grown on an r-plane sapphire substrate, and epitaxial lateral overgrowth was achieved using SiO 2 masks. A comparison between the properties of GaN directly grown on sapphire and GaN laterally grown over the SiO 2 mask is presented. The densities and dimensions of the stacking faults vary significantly with a high density of short faults in the window region and a much lower density of longer faults in the wing region. The low-temperature luminescence spectra consist of peaks at 3.465 and 3.41 eV, corresponding to emission from donor-bound excitons and basal-plane stacking faults, respectively. A correlation between the structural defects and the light emission characteristics is presented.

InGaN quantum wells, grown on non-polar m-plane GaN and emitting light at 560 nm, experience lattice mismatch strain relaxation by the generation of stacking faults. Each stacking fault terminates a basal plane from the substrate side, generating misfit dislocations that have a Burgers vector with a 1/2[0001] component. The structural and optical properties of such thin film structures are reported.

Recently, multipole plasmonic mode resonances in metal hollow structures, such as dipole, quadrupole, and octupole modes, have been widely investigated by researchers with the aim for potential applications in bio-sensing, fluorescence, nanolasers or nonlinear nano-photonics. Here, in this work, the multipole plasmon resonances in self-assembled metal hollow-nanospheres (HNSs) are theoretically and experimentally demonstrated and the hot spots originating from the higher order mode plasmonic resonance and interparticle coupling effect are proposed to be used for Raman scattering enhancements. Dipole, quadrupole, octupole and hexadecapole mode plasmonic resonances were clearly resolved in the extinction spectra of these Ag HNS arrays showing good agreement with the theoretical simulation results. Strong regular hot spots were obtained around the surface and in the gaps of the Ag HNSs through the higher order mode plasmonic resonances and corresponding interparticle coupling effect between the HNSs. Maximum local field intensity was accomplished by optimizing the size of as well as the coupling distance between the HNSs and then it was applied to SERS sensing. Raman mapping also demonstrated these self-assembled plasmonic cavity arrays to be a stable and uniform SERS-active substrate.