Characterization of silicon nitride thin films deposited by hot-wire CVD at low gas flow rates

We examined the chemical, structural, mechanical and optical properties of amorphous hydrogenatedsilicon nitride thin films deposited by hot-wire chemical vapour deposition using SiH4, NH3and H2gases at total flow rates below 33 sccm. Time of flight secondary ion mass spectroscopy reveal that thefilm surfaces consist of predominantly Si with hydrogenated SixNyOzspecies. Energy dispersive X-rayspectroscopy and X-ray photoelectron spectroscopy corroborate on the N/Si ratio. Electron energy lossspectroscopy discloses that the thickness of the nitrogen rich oxidized interface between the SiNxfilmsand the c-Si substrate decrease with an enhancing NH3flow rate. By varying the NH3flow rate, denseSiNxfilms can be realized with hydrogen content between 16 and 9 at.%, a refractive index between 3.5and 1.9 and optical band gap ranging from 2 to 4.5 eV. The SiNxfilm stress is compressive for N/Si 0.55. Mechanisms relating the HWCVD conditions and the film structure andproperties are proposed.Web of Scienc

Controlled deposition of lead iodide and lead chloride thin films by low-pressure chemical vapor deposition

Lead halide thin films, such as lead iodide (PbI2) and lead chloride (PbCl2), are used as precursor films for perovskite preparation, which is frequently achieved by vacuum thermal evaporation but rarely by the low-pressure chemical vapor deposition (CVD) method. Here, we report on the deposition of PbI2 and PbCl2 thin films on glass substrates by employing the low-pressure CVD method. The effect of the substrate temperature on the structure and morphology of the lead halide films is investigated. Crystalline films were realized for both lead halides, with PbI2 films showing high texture compared to the reduced texture of the PbCl2 films. Large lateral grain sizes were observed for the PbI2 films with a flat platelet grain morphology and an average grain size up to 734.2 ± 144.8 nm. PbCl2 films have columnar grains with an average grain size up to 386.7 ± 119.5 nm. The PbI2 films showed a band gap of about 2.4 eV, confirming its semiconducting properties, and the PbCl2 had a wide band gap of 4.3 eV, which shows the insulating properties of this material

Influence of Synthesis Method on Structural, Morphological, Magnetic, and Antimicrobial Properties of Fe-Ag Nanoparticles

This contribution reports on the development of two versatile and efficient methods, namely the green and gamma radiolysis for Fe-Ag nanoparticles (NPs) synthesis, characterization, and further their growth inhibition potential on some spoilage microorganisms. Green Ag/Fe2O3 NPs were obtained at Fe-Ag [3:1], annealing temperature of 800 °C for 2 h, and gamma irradiated Ag/Fe3O4 NPs were obtained at Fe-Ag [7:1], a 50 kGy dose. The characterization techniques were performed with these two samples whereby the sizes from crystallographic and microscopic analyses were 39.59 and 20.00 nm for Ag/Fe2O3 NPs, 28.57 and 15.37 nm for Ag/Fe3O4 NPs, respectively. The polycrystallinity nature observed from X-ray diffraction was in accordance with the selected area electron diffraction. The vibrational properties confirmed the presence of bimetallic Fe-Ag NPs with the depiction of chemical bonds, Fe–O and Ag–O from attenuated total reflection-Fourier transform infrared spectroscopy and elements Ag, Fe, O from energy-dispersive X-ray spectroscopy analyses. The magnetic properties carried out using a vibrating sample magnetometer suggested a superparamagnetic behavior for the Ag/Fe2O3 NPs and a ferromagnetic behavior for the Ag/Fe3O4 NPs. Overall, the green Ag/Fe2O3 NPs successfully inhibited the growth of spoilage yeasts Candida guilliermondii, Zygosaccharomyces fermentati, Zygosaccharomyces florentinus, and spoilage molds Botrytis cinerea, Penicillium expansum, Alternaria alstroemeriae

Self-Catalytic Growth of Tin Oxide Nanowires by Chemical Vapor Deposition Process

We report on the synthesis of tin oxide (SnO 2 ) nanowires by a chemical vapor deposition (CVD) process. Commercially bought SnO nanopowders were vaporized at 1050 ∘ C for 30 minutes with argon gas continuously passing through the system. The assynthesized products were characterized using UV-visible absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM). The band gap of the nanowires determined from UV-visible absorption was around 3.7 eV. The SEM micrographs revealed "wool-like" structure which contains nanoribbons and nanowires with liquid droplets at the tips. Nanowires typically have diameter in the range of 50-200 nm and length 10-100 m. These nanowires followed the vapor-liquid-solid (VLS) growth mechanism

Grain structure orientational change in Ti6Al4V alloys induced by sea water quenching and novel stress relief annealing process

We report on the microstructures and properties of Ti6Al4V alloys, which were achieved upon quenching in sea water medium with potential high cooling rate. The Ti6Al4V alloys were quenched at 1000 and 1100 ◦C, respectively. Moreover, the effect of post-quenching annealing performed at 900 ◦C was analyzed. As a result, the quenched alloy experienced surface thermal stress, due to rapid cooling and thermal shock, due to exposure to high temperature annealing

Comparative study: the effect of annealing conditions on the properties of P3HT:PCBM blends

This paper presents a detailed study on the role of various annealing treatments on organic poly(3-hexylthiophene) and [6]-phenyl-C61-butyric acid methyl ester blends under different experimental conditions. A combination of analytical tools is used to study the alteration of the phase separation, structure and photovoltaic properties of the P3HT:PCBM blend during the annealing process. Results showed that the thermal annealing yields PCBM ‘‘needle-like’’ crystals and that prolonged heat treatment leads to extensive phase separation, as demonstrated by the growth in the size and quantity of PCBM crystals. The substrate annealing method demonstrated an optimal morphology by eradicating and suppressing the formation of fullerene clusters across the film, resulting in longer P3HT fibrils with smaller diameter. Improved optical constants, PL quenching and a decrease in the P3HT optical bad-gap were demonstrated for the substrate annealed films due to the limited diffusion of the PCBM molecules. An effective strategy for determining an optimized morphology through substrate annealing treatment is therefore revealed for improved device efficiency.Web of Scienc

Complete Genome Sequences of Cluster A Mycobacteriophages BobSwaget, Fred313, KADY, Lokk, MyraDee, Stagni, and StepMih

Seven mycobacteriophages from distinct geographical locations were isolated, using Mycobacterium smegmatis mc2155 as the host, and then purified and sequenced. All of the genomes are related to cluster A mycobacteriophages, BobSwaget and Lokk in subcluster A2; Fred313, KADY, Stagni, and StepMih in subcluster A3; and MyraDee in subcluster A18, the first phage to be assigned to that subcluster

Elemental Cu doped Co3O4 thin film for highly sensitive non-enzymatic glucose detection

We report on the non-enzymatic glucose sensing ability of elemental Cu doped Co3O4 thin film deposited on FTO in this study. A facile chemical solution method was used to substitute elemental Cu into the Co3O4 host lattice. The morphology of the electrode was characterized by XRD, SEM, HRTEM, SAED and EELS. The as prepared thin film exhibited very high sensitivity of 1850 μAcm-2 mM−1, and linear range up to 7.6 mM. The sensor showed a limit of detection of 153 nM at a signal to noise ratio of 3. The developed sensor was used successfully to measure glucose level in human serum and spiked saliva samples. Keywords: Co3O4, Non-enzymatic sensor, Glucose sensor, Thin fil

Controlled Deposition of Lead Iodide and Lead Chloride Thin Films by Low-Pressure Chemical Vapor Deposition

Lead halide thin films, such as lead iodide (PbI2) and lead chloride (PbCl2), are used as precursor films for perovskite preparation, which is frequently achieved by vacuum thermal evaporation but rarely by the low-pressure chemical vapor deposition (CVD) method. Here, we report on the deposition of PbI2 and PbCl2 thin films on glass substrates by employing the low-pressure CVD method. The effect of the substrate temperature on the structure and morphology of the lead halide films is investigated. Crystalline films were realized for both lead halides, with PbI2 films showing high texture compared to the reduced texture of the PbCl2 films. Large lateral grain sizes were observed for the PbI2 films with a flat platelet grain morphology and an average grain size up to 734.2 ± 144.8 nm. PbCl2 films have columnar grains with an average grain size up to 386.7 ± 119.5 nm. The PbI2 films showed a band gap of about 2.4 eV, confirming its semiconducting properties, and the PbCl2 had a wide band gap of 4.3 eV, which shows the insulating properties of this material