Plasma Deposited Electrocatalytic Films with Controlled Content of Pt Nanoclusters

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Surface Texturing of n- and p-Doped c-Si Using a Novel Plasma Chemical Texturing Process

Abstract n- and p-doped c-Si (100) are textured by a SF 6 /O 2 plasma chemical etching, under conditions avoiding ion bombardment. The study of the effects of plasma parameters on morphology and on surface reflectance of textured c-Si reveals a strong impact of silicon doping on texturing characteristics. SF 6 /O 2 plasma etches anisotropically n-type c-Si creating a square-based hillock-like morphology with a surface reflectivity of 6%. Conversely, for p-type Si, a H 2 plasma pretreatment is necessary to activate silicon etching and obtain a nano-textured surface with a reflectivity of 16%

Interlaboratory study on Sb2S3 interplay between structure, dielectric function, and morphous-to-crystalline phase change for photonics

Antimony sulfide, Sb2S3, is interesting as the phase-change material for applications requiring high transmission from the visible to telecom wavelengths, with its band gap tunable from 2.2 to 1.6 eV, depending on the amorphous and crystalline phase. Here we present results from an interlaboratory study on the interplay between the structural change and resulting optical contrast during the amorphous-to-crystalline transformation triggered both thermally and optically. By statistical analysis of Raman and ellipsometric spectroscopic data, we have identified two regimes of crystallization, namely 250_C % T < 300_C, resulting in Type-I spherulitic crystallization yielding an optical contrast Dn _ 0.4, and 300 % T < 350 _ C, yielding Type-II crystallization bended spherulitic structure with different dielectric function and optical contrast Dn _ 0.2 below 1.5 eV. Based on our findings, applications of on-chip reconfigurable nanophotonic phase modulators and of a reconfigurable high-refractive-index core/phase-change shell nanoantenna are designed and proposed.The authors acknowledge the support from the European Union’s Horizon 2020 research and innovation program (No 899598 - PHEMTRONICS)

Plasma Deposited Electrocatalytic Films with Controlled Content of Pt Nanoclusters

Combining platinum sputtering with plasma polymerization in argon-ethylene plasmas, nanocomposite Pt-hydrocarbon thin films, useful as catalytic layers for proton exchange membrane fuel cells, can be deposited. Pulsing the ethylene flow rate allowed for a fine tuning of the Pt amount in deposited films at low RF input power. The proposed deposition process seems to be an efficient strategy to control the metal content over a wide range of atomic percentages (5-80%). Deposited films were characterized in terms of their chemical, electrochemical and structural properties. The XPS spectra revealed that platinum is included in the films in metallic state. SEM and TEM analyses showed that nanosized Pt clusters (3-7 nm diameter) are uniformly distributed in a porous columnar film structure. The best electrochemical activity (202 cm 2 · mg Pt-1) was achieved with a 500 nm thick thin film containing 0.56 mg Pt · cm -2 of catalyst. High performance electro-catalytic hydrocarbon thin films containing Pt nano-clusters are deposited combining platinum sputtering with plasma polymerization in Ar-ethylene plasmas. The process originality relies on pulsing the monomer mass flow rate that permits an accurate and reproducible control of the metal content over a wide range of concentrations at low power

Electrophoretic deposition of Au NPs on MWCNT-based gas sensor for tailored gas detection with enhanced sensing properties

Multiwalled carbon nanotube (MWCNT)-based gas sensors were decorated by an electrophoretic deposition of electrochemically preformed gold nanoparticles (Au NPs) with controlled size and loading, for the detection of gaseous pollutants at sub-ppm concentrations and operating temperature in the range of 100-200 °C. The effects of the tailored Au content on the sensitivity and selectivity of MWCNT-based gas sensors were evaluated towards the NO2 monitoring, and also towards some interfering reducing gases, such as NH3 and H2S. Gas sensing measurement revealed the highest NO2 response up to sub-ppm level by using MWCNTs functionalized by the lowest Au content; instead, the worse NO2 response was obtained by modified MWNTs containing the highest Au loading. Moreover, the control of the deposited gold loading has allowed to control the MWCNT sensing response; specifically the increase of gold content on MWCNT has reduced the selectivity and sensitivity towards NO2 gas, and, on the contrary, at the same time it has improved those towards H2S and NH3 interfering gases. Finally, binary gas mixtures (NO2/H2S and NO2/NH3) were performed to evaluate the detection of the targeted NO2 gas, simulating possible real-world conditions

Interplay between solid-state organization and optical properties of thin films of poly-arylene-vinylene and -difluorinated vinylene: Fullerene blends

application in organic polymer solar cells. A large variety of low bandgap polymers are prepared by alternating copolymerization of electron-donating donor and electron-withdrawing acceptor units. The interaction between these two units can reduce the polymer bandgap, increasing the sunlight absorption. Benzothiadiazole is commonly used as acceptor block unit in low bandgap polymers. In this contribution we investigate the supramolecular organization and optical properties of thin films of conjugated polymers consisting of benzothiadiazole and thiophene with electron-withdrawing difluorovinylene, and electron-donating vinylene substituents. Atomic force microscopy and spectroscopic ellipsometry are exploited for the analysis of the morphology and optical transitions, respectively. It is found that F-atoms in the vinylene unit yield a blue-shift of the absorption peaks of 0.2 eV respect to the hydrogenated polymer and an increase in the absorption coefficient of fluorinated polymers, which indicates their potential application as photovoltaic material. The morphology evolution of the conjugated polymers blended with a fullerene derivate ([6,6]-phenyl C61-butyric acid methyl ester, PCBM) is also investigated by atomic force microscopy.??