This letter reports blue oxynitride phosphors of La1−xCexAl(Si6−zAlz)(N10−zOz) (z∼1) (termed JEM crystal phase) and their application for the white light-emitting diodes (LEDs). The JEM phosphor can be excited by 405nm light efficiently, and its spectrum can be tuned widely by changing the Ce concentration. The emission spectrum of this phosphor is as wide as 110nm in full width at half maximum, which is convenient to solid state lighting. The preparation of white LED was attempted by using a 405nm InGaN chip and oxynitride phosphors in this work. High color rendering index >95 was achieved in white LED with various correlated color temperatures, indicating the suitability of the JEM phosphor in solid-state lightings.
The photoluminescence (PL) and PL excitation (PLE) spectra of Si Al O N (β-sialon):Eu phosphors with small values (=0.025-0.24) were studied at room temperature and 6 K. The PL and PLE spectra exhibit fine structure with the PL lines being as sharp as 45-55 nm even at room temperature; this fine structure was enhanced by decreasing the value. These results can be used for expanding the color gamut of liquid crystal displays, particularly in the blue-green region. From low-temperature measurements, the fine PLE structure was ascribed to discrete energy levels ofF states. The 4f5d excited states of Eu are considered to be localized near the 4f orbital. This is because the bonding of Eu with surrounding atoms is ionic rather than covalent. Lattice phonon absorptions were also observed in the PLE spectrum, revealing that the optically active Eu ions are located in the β-sialon crystal. The PL spectrum of the sample with the smallest value (0.025) consists of a sharp zero-phonon line and lattice phonon replicas, which results in a sharp and asymmetric spectral shape.
In this work, SiAlON phosphor–glass films were investigated as wavelength converters in solid-state laser lighting. The phosphor–glass composite films were prepared by dispersing phosphor powders into a silica precursor solution and sintering at 500 °C. Both simulation and experiment were carried out to evaluate the optical properties of solid-state lighting devices using SiAlON:Eu or YAG:Ce–glass films. The device using SiAlON:Eu phosphors initially has lower brightness than that of the device using YAG:Ce at lower laser powers, but the latter has an illuminance saturation at 1000 lx whereas the SiAlON-based device is free of saturation even at higher laser powers. The device using SiAlON phosphor–glass composite films has a maximum illuminance 15% higher than that of the device using YAG when the temperature exceeds 250 °C. These better optical properties are ascribed to the higher thermal stability of SiAlON phosphors that are able to achieve high luminance and thermally robust solid-state lighting.
Cu interconnects are used in semiconductor devices and their dimensions are downscaled markedly. Cu interconnects are fabricated by a damascene process, and it becomes difficult to fill Cu into trenches and vias structures by electroplating below the 20 nm feature size. We evaluated the process integration for Cu interconnects using a Co wetting layer by chemical vapor deposition (CVD), a Cu seed by magnetic-field-assisted ionized sputtering (MFIS) and a Cu reflow technique. The properties of a CVD-Co film, such as composition, resistivity, step coverage, and adhesion between Cu and Co, were investigated. By using CVD-Co as the wetting layer, the properties of Cu gap filling in a trench structure were improved, and the filling of Cu into a 14-nm-wide trench structure was achieved.
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