ABSTRACT
High quality GaN epilayers were obtained by using a magnesium nitride (MgxNy) inter-layer. X-ray photoelectron spectroscopy (XPS) reveals Mg 2p core-level spectra from the MgxNy inter-layers. The roughness of the MgxNy layers increased with the growth time, though a prolonged processing time resulted in a decrease in the roughness. A high-resolution X-ray diffraction ω-scan rocking curve was used to reveal that the screw dislocation density (TDD) of GaN with an MgxNy inter-layer was reduced and the crystalline quality of the GaN epitaxial layer was enhanced. Furthermore, the luminous efficiency of an LED with the MgxNy layers was increased by 20% relative to a reference LED.
ABSTRACT
The surface plasmon resonance (SPR) properties of Au/Ag bimetallic thin-film nanostructures were investigated to improve the chemical stability and the figure of merit (FOM) in the SPR sensors. The SPR characteristics such as resonance angle, extinction ratio, and full width half maximum (FWHM) were calculated by the simulation of the finite-difference time-domain method and were measured using the laser with a 632.8 nm wavelength in the Kretschmann-Raether configuration. The measured resonance angle, extinction ratio, FWHM of Au(20 nm)/Ag(20 nm) thin-film nanostructure were found to be 44°, 0.8, and 1.4°, respectively. The FOM values were determined to be 56.9 for Au/Ag bimetallic thin-film, 47.9 for Au(50 nm) single thin-film, and 89.1 for Ag(50 nm) single thin-film. Also the sensitivity values were about 53.5, 57.0, and 57.8°/RIU for Au(50 nm), Ag(50 nm), and Au(20 nm)/Ag(20 nm) thin-film nanostructures in the SPR sensors, respectively. The SPR properties of Au/Ag bimetallic thin-film nanostructures were compared with those of the Au and Ag single thin-film nanostructures.
ABSTRACT
The Zn0.8-xMg0.2BexO/Cu/Ag/Zn0.8-xMg0.2BexO multilayer structures were designed, sputter-deposited at room temperature, and characterized in detail. Results indicated that the multilayer structures with high transmission (higher than 90% at the visual wavelength range) can be readily obtained by simply inserting a thin (â¼5 nm) Cu wetting layer, which renders the thin Ag layers (â¼5 nm thick) continuous and smooth. It was also observed that the optical absorption edges of the multilayer structures increase as the energy band-gaps of the top/bottom oxide layers increase and the multilayer structures with the energy band gap of â¼6.0 eV can be obtained by employing the ZnMgBeO layers, with an excellent resistivity of â¼1.7 × 10-4 Ω cm. These results represent a significant improvement over the previous reports and the first report on the design and fabrication of the highly conducting transparent materials for the UV-C application.
