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Determining a Line Strength in the ν <sub/>3</sub> Band of the Silyl Radical Using Quantum Cascade Laser Absorption Spectroscopy
摘要： Silane (SiH4) plasmas are widely used for the deposition of hydrogenated amorphous silicon (a-Si:H) films. Nevertheless, the chemical processes governing film deposition are still incompletely understood. Moreover, there is still no general method available to determine the absolute concentration of the silyl radical (SiH3), which is the accepted chemical precursor of a-Si:H films. In this study, a 10% silane in helium RF plasma was spectroscopically investigated between 2085 and 2175 cm?1 using an external cavity quantum cascade laser (EC-QCL) based spectrometer. This led to the identification of 4 distinct species from their absorption features: SiH4, disilane (Si2H6), SiH3, and an unassigned short-lived species. Furthermore, 17 absorption features of SiH3 were identified and unambiguously assigned. Fast spectral scanning of selected absorption features belonging to the four species in a 10 Hz pulsed RF plasma enabled the measurement and interpretation of their temporal behavior in terms of plausible chemical reactions involving silicon containing species. By quantitatively measuring the decay of the SiH3 a ← a pP4 (5) transition at 2151.3207 cm?1 after the discharge was stopped, its line strength (S) was determined to be (7.5 ± 5.5) × 10?20 cm2 cm?1 mol?1.
关键词： quantum cascade laser absorption spectroscopy,hydrogenated amorphous silicon,Silane plasmas,line strength,silyl radical
更新于2025-09-12 10:27:22
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Nanosecond Pulsed Laser Processing Turns Engineering Metal Alloys Antireflective and Superwicking
摘要： In this work, superwicking and antireflective properties are achieved on engineering metal surfaces by creating surface pattern using a high pulse energy nanosecond laser followed by a chemical immersion treatment. The high-energy nanosecond pulse laser scans the metal surface in air. Subsequently, the laser-textured surface is further treated by immersion in a 3-cyanopropyltricholosilane reagent. As a result of these two processes, microgrooves with micro- and nano-scale surface features are generated on the metal surface. Due to the created surface structure and favorable surface chemistry, water sprints uphill defying the gravity. The fast self-propelling movement of water is due to the supercapillary effect of the surface microchannel and the superhydrophilic surface nitrile group. The wicking effect on the processed surface follows the classical square root of time dependence. The processed surface shows good antireflective properties in visible and infrared spectrum. Surface features, surface chemistry, surface wettability, surface reflectivity and surface wicking behavior are measured on AA6061 and Ti-6Al-4V specimens through Scanning Electron Microscopy (SEM), X-ray Photoelectron Spectroscopy (XPS), contact angle goniometer, UV-VIS-NIR spectrometer and high-speed camera.
关键词： Nitrile,Superwicking,Capillary,Nanosecond Laser,Silane
更新于2025-09-12 10:27:22
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AIP Conference Proceedings [AIP Publishing 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - Fes, Morocco (25–27 March 2019)] 15th International Conference on Concentrator Photovoltaic Systems (CPV-15) - P-type SiOx front emitters for Si heterojunction solar cells
摘要： We have applied p-type nanocrystalline silicon-oxide (p-SiOx) as front emitter in silicon heterojunction solar cells. The evolution of structural, optical, and electrical properties of p-SiOx as a function of the carbon-dioxide/silane flow rate ratio used in the gas mixture has been investigated, comparing also the film characteristics with those of p-type amorphous and nanocrystalline silicon thin films often used in the cells. Selected p-SiOx films with suitable electrical properties have been inserted in silicon heterojunction solar cells based on n-type FZ c-Si <100> wafers, passivated with ultrathin intrinsic a-Si:H buffers. Improvement of all the photovoltaic parameters has been observed with the emitter with higher oxygen content. The results have been correlated with the increased transparency and enhanced field-effect passivation obtained thanks to the presence of sufficient carbon dioxide in the gas mixture for the p-SiOx layer growth.
关键词： field-effect passivation,silicon heterojunction solar cells,p-type nanocrystalline silicon-oxide,optical and electrical properties,carbon-dioxide/silane flow rate ratio
更新于2025-09-11 14:15:04
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Photopolymerization synthesis of polyacrylic acid dispersant with methoxysilicon end groups and its application in nano-SiO <sub/>2</sub> aqueous system
摘要： In order to improve the dispersity and stability of nano-SiO2 aqueous system with high solid content, a kind of polyacrylic acid dispersant with methoxysilicon end groups (KH590-PAA) was synthesized by photopolymerization of acrylic acid (AA) initiated with (3-mercaptopropyl)trimethoxysilane (KH-590). After adding KH590-PAA into nano-SiO2 aqueous dispersion system (20 wt% solid content), the viscosity and the curing time of the system were measured by rotational viscometer and the inverted bottle method. Moreover, the dispersion mechanism of KH590-PAA for nano-SiO2 aqueous system was researched by measuring the adsorption capacity, the particle size and the zeta potential of nanoparticles with conductivity meter, dynamic light scattering (DLS), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The results showed that methoxysilicon groups in KH590-PAA could react with hydroxyl groups on the surface of nano-SiO2 in the process of stirring, which enhanced the adsorption capacity of the dispersant and then increased the surface charge of the particles. Therefore, electrostatic repulsion and steric hindrance effects between SiO2 nanoparticles could further be enhanced by adding the KH590-PAA dispersant, and then the nano-SiO2 aqueous system exhibited better dispersity and stability. Besides, the dispersion properties of SiO2 nanoparticles in water were closely related to the addition amount and the molecular weight of the KH590-PAA dispersant.
关键词： Dispersion,Photopolymerization,Silane coupling agent,SiO2 nanoparticle,Polyacrylic acid
更新于2025-09-10 09:29:36
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Surface grafting modification of titanium dioxide by silane coupler KH570 and its influences on the application of blue light curing ink
摘要： A series of reactive TiO2 pigments with olefinic double-bonds were prepared by grafting modification of silane coupler KH570 to be covalently anchored in the blue-light curing film, which improved the color fastness to crocking of the printed fabrics significantly. Effects of KH570 concentrations on particle size, surface wettability and dispersing stability of KH570-TiO2 pigments, photo-polymerization of KH570-TiO2 bule-light curing inks and tensile properties of curing films were investigated. Color fastness to crocking of KH570-TiO2 pigment on cotton fabric was explored. Results showed that compared to the native TiO2, all the properties of KH570-TiO2 improved. With the increases of KH570 concentrations, the grafting degrees of KH570-TiO2 had gradual increase. The surface hydrophobicity and dispersion stability of KH570-TiO2 pigments, photo-polymerization of KH570-TiO2 blue-light curing ink and tensile properties of curing films enhanced, especially those of 12KH570-TiO2~20KH570-TiO2 the best. Within the concentrations of KH570 12～20 wt %, the printed fabrics had dry/wet color fastness to crocking no less than 4 grades.
关键词： printing ink,grafting,blue-light curing,Titanium dioxide,silane coupler
更新于2025-09-09 09:28:46