Phase mixture and anti-reflection window in visible of annealed beryllium-nitride thin films on silicon crystal

Beryllium-nitride (Be 3N 2) thin films were grown on silicon Si(1 1 1) substrates by pulsed laser deposition in a RIBER LDM-32 system, and characterized with in/ex situ XPS and SIMS. The structure of the films was analyzed with XRD. The films were further analyzed for surface topographic information with SEM and profilometry, and for optical properties with optical spectroscopy. It was observed that the material, prepared at room temperature and annealed at 700 °C for 2 h, had undergone a partial phase transition to a mixture of amorphous and crystalline phases, and the thin films showed a large anti-reflection window in the visible. Therefore, the annealed Be 3N 2 thin films would be potentially useful for stable electronic packaging with desired photonic features. © 2011 Elsevier GmbH. All rights reserved

Synthesis and characterization of (3-Aminopropyl)trimethoxy-silane (APTMS) functionalized Gd₂O₃:Eu³⁺ red phosphor with enhanced quantum yield

We report the surface modification of nanocrystalline Gd2O3:Eu3+ phosphor by (3-Aminopropyl)trimethoxysilane (APTMS). The nanoparticles were first coated with silica using the Stöber process, and then annealed at 650 °C for 2 h. Afterwards, APTMS was functionalized onto the silica layer to obtain Gd2O3:Eu3+ nanoparticles bearing amine groups on the surface. The effect of silica coating, and the subsequent annealing process on the crystallization of the nanophosphor were analyzed by x-ray diffraction (XRD). High-resolution transmission electron microscopy (HR-TEM) confirmed the presence of a silica layer of ∼45 nm thickness. X-ray photoelectron (XPS) and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of silica and the amine groups. Photoluminescence (PL) analysis demonstrated an increased emission after functionalization of nanoparticles. Absolute quantum yield (QY) measurements revealed an 18% enhancement in QY in functionalized nanoparticles compared with unmodified nanoparticles, which is of great importance for their biomedical applications