Structural and emission properties of Tb3+-doped nitrogen-rich silicon oxynitride films

Growth of Homogeneous Luminescent Silicon-Terbium Nanowires by One-Step Electrodeposition in Ionic Liquids

An electrodeposition method for the growth of homogeneous silicon-terbium nanowires (NWs) with green light emission is described. The method involves template-assisted electrochemical co-deposition of Si/Tb NWs with 90-nm diameter from an electrolyte bath containing Si and Tb precursors in an ionic liquid (IL). This method of deposition is advantageous over other conventional techniques as it is relatively simple and cost-effective and avoids harsh deposition conditions. The deposited NWs are of uniform dimensions with homogeneous composition incorporating 10% of Tb and exhibit intense room temperature (RT) luminescence in the visible range due to Tb emission. These results were confirmed by combining classical characterization such as scanning electron microscopy (SEM) and photoluminescence (PL) performed on an assembly of NWs with spatially resolved experiments such as transmission electron microscopy (TEM) and cathodoluminescence (CL). This electrodeposition method provides an alternative and extremely simple approach for depositing silicon-rare earth nanostructures for optical and sensing applications.

A Review: Preparation, Performance, and Applications of Silicon Oxynitride Film

Silicon oxynitride (SiN_xO_y) is a highly promising functional material for its luminescence performance and tunable refractive index, which has wide applications in optical devices, non-volatile memory, barrier layer, and scratch-resistant coatings. This review presents recent developments, and discusses the preparation methods, performance, and applications of SiN_xO_y film. In particular, the preparation of SiN_xO_y film by chemical vapor deposition, physical vapor deposition, and oxynitridation is elaborated in details.

Correlation between composition, microstructure, and emission properties in Nd-doped Si-rich Si oxynitride films: investigation into the nature of the sensitizer

Rare earth (RE) ions doped in Si-based materials, compatible with Si technology, are promising compounds with regards to optical communication and energy conversion. In this article, we show the emission properties of Nd-doped Si-rich Si oxynitride (Nd-SRSON) films, and their dependence on the dangling bond density and the nature of the sensitizer. These films were prepared by reactive magnetron sputtering and post-annealing. The film composition, microstructure, and emission properties were investigated as a function of deposition parameters and annealing temperatures. Both Fourier transform infrared (FTIR) and ellipsometry spectroscopy measurements have confirmed that the sample composition (Si/N ratio) can be carefully tuned by varying the ratio of reactive nitrogen to argon in the sputtering plasma. Moreover, FTIR and x-ray photoelectron spectroscopy measurements demonstrate the existence of both nitrogen and oxygen dangling bonds (N· and O·) in as-deposited samples. These dangling bonds were passivated during annealing. Under non-resonant excitation at 488 nm, the films exhibit a significant photoluminescence (PL) signal from Nd³⁺ ions demonstrating the occurrence of an effective sensitization of Nd³⁺ ions in the host matrix. Both PL excitation and ellipsometry results (the energy band gap from new amorphous model) exclude the sensitization by an exciton with energy over the band gap, whereas the presence of Si agglomerates, at the atomic scale, have been identified as effective sensitizers towards Nd³⁺ ions. This work not only provides knowledge to optimize Si-based materials for favorable emission properties, but also, presents a universal methodology to investigate the nature of sensitizers for RE emitters. This allows one to find correlations between composition, microstructure, and emission properties.

Tuning the N-bonded cerium(iii) fraction/g-C3N4 interface in hollow structures using an in situ reduction treatment for superior photochemical hydrogen evolution

Hybridized N-CeO₂/g-C₃N₄ hollow structures show CeO₂ surface oxygen vacancy population for enhanced hydrogen evolution.

The nitrogen concentration effect on Ce doped SiOxNy emission: towards optimized Ce3+ for LED applications

Ce-Doped SiO_xN_y films are deposited by magnetron reactive sputtering from a CeO₂ target under a nitrogen reactive gas atmosphere. Visible photoluminescence measurements regarding the nitrogen gas flow reveal a large emission band centered at 450 nm for a sample deposited under a 2 sccm flow. Special attention is paid to the origin of such an emission at high nitrogen concentration. Different emitting centers are suggested in Ce doped SiO_xN_y films (e.g. band tails, CeO₂, Ce clusters, Ce³⁺ ions), with different activation scenarios to explain the luminescence. X-ray photoelectron spectroscopy (XPS) reveals the exclusive presence of Ce³⁺ ions whatever the nitrogen or Ce concentrations, while transmission electron microscopy (TEM) shows no clusters or silicates upon high temperature annealing. With the help of photoluminescence excitation spectroscopy (PLE), a wide excitation range from 250 nm up to 400 nm is revealed and various excitations of Ce³⁺ ions are proposed involving direct or indirect mechanisms. Nitrogen concentration plays an important role in Ce³⁺ emission by modifying Ce surroundings, reducing the Si phase volume in SiO_xN_y and causing a nephelauxetic effect. Taking into account the optimized nitrogen growth parameters, the Ce concentration is analyzed as a new parameter. Under UV excitation, a strong emission is visible to the naked eye with high Ce³⁺ concentration (6 at%). No saturation of the photoluminescence intensity is observed, confirming again the lack of Ce cluster or silicate phase formation due to the nitrogen presence.