Papers by Keyword: SiO₂

Abstract: This paper presents process integration of atomic layer deposition (ALD) SiO₂ as gate dielectric in the 1.7 kV SiC trench UMOSFET. This integration provides a solution for embedding complementary metal oxide semiconductor (CMOS) circuits into the UMOSFET power device, enabling the realization of smart power management integrated circuit (IC) functions in the future. 4H-SiC power MOSFETs have gained increased attention in medium to high power applications recently due to their wide bandgap, high breakdown electric field, and excellent thermal conductivity. The electric vehicle (EV) is one example of an application where the Tesla Model 3 utilizes SiC 650V VDMOSFETs as driving components in its inverter design. Trench MOSFETs are key to achieving these requirements to further scale down power devices while decreasing the specific on-state resistance (R_on,sp). This is challenging with thermal gate oxide on SiC trench MOSFETs due to the anisotropic thermal oxide growth rate on the sidewalls and the bottom of trench or mesa region. Therefore, we propose a novel fabrication process by integrating ALD SiO₂ gate oxide into trench UMOSFET. The R_on,sp of the fabricated device can be reduced to 2.3mΩ-cm², accompanied by a very low density of interface states (D_it) of approximately 5.36x10¹⁰ eV^-1cm^-2. Another feature of this ALD SiO₂ solution for gate oxide is the monolithic integration of the CMOS circuit with the UMOSFET, enabling the realization of smart power IC management.

Abstract: The total ionising dose (TID) reliability of a phosphorous pentoxide (P₂O₅) treated SiO₂ (silicon dioxide) layer is compared for the first time to other industrially relevant oxides formed on 4H-silicon carbide (SiC). Metal-oxide-semiconductor capacitors (MOSCAPs) are characterised before and after irradiation to ascertain changes in flat band voltage shift, leakage current, and dielectric breakdown (BV). Secondary ion mass spectrometry (SIMS) profiling reveals a significant phosphorus concentration near the SiO₂/SiC interface, which led to improved TID resistance. The P₂O₅ treated oxide had the lowest leakage current at high voltage bias due to the high-temperature (1,000°C) anneal, though it had a significantly negative flat band voltage due to the high concentration of deposited phosphorus atoms. The thermal and P₂O₅ oxides demonstrated a TID resistance, suffering only minor shifts in flat band voltage, while the P₂O₅ oxide suffered the smallest decrease in its BV and the smallest leakage current rise, post-irradiation.

Abstract: In this work, we investigate the use of reflectance spectroscopy as an accurate, fast, and non-destructive method for measuring the thickness of transparent layers, such as SiO₂, with thicknesses below 200 nm for microelectronic applications. To this end, we fabricated different oxides and analyzed their reflectance spectra using reflectance spectroscopy. The results were compared to theoretical reflectance spectra to validate the method. We introduce key factors to ensure accurate measurement by modeling the reflectance spectra of thin oxide layers with thicknesses ≥ 15 nm on 4H-SiC using the transfer matrix method (TMM).

Abstract: Bitumen, a fundamental component of asphalt used in road construction, plays a vital role in determining the performance and longevity of pavements. The assessment of bitumen characteristics is crucial to ensure its suitability for specific applications and environmental conditions. This research paper explores the use of fumed silica, a high-purity, fine particulate form of silicon dioxide, as an additive in bitumen to improve its properties. The study investigates the impact of Fumed Silica SiO2 on the results obtained. The following tests, including the specific gravity test, penetration test, softening point test, and flash and fire test were used to determine the rheological characteristics of bitumen. In particular, the treated bitumen qualities were concentrated after performing lab testing by breaking down the rheological properties. The research aims to enhance the understanding of how SiO2 affects bitumen properties and its potential benefits in enhancing the performance of road pavements. According to this study, 0.1 wt. % of fumed silica produces the results mentioned above better than larger concentrations of fumed silica.

Abstract: Metal is widely used in various industrial fields such as transportation because of its physical and mechanical strength. However, during its utilization, metal materials are often damaged by corrosion due to chemical reactions between the metal surface and the surrounding environment. Coating is one way to prevent corrosion by isolating metal surfaces from the environment. Conventional anti-corrosion coatings generally use chromate and phosphate-based materials. However, this material has been banned in some countries because it is toxic to the environment. Meanwhile, other methods with the addition of more active metals such as magnesium are considered unaffordable. Therefore, the researchers developed alternative materials that are environmentally friendly and reduce costs by using metal oxide-based materials such as Silicon dioxide (SiO₂). The advantage of SiO₂ is that it is chemically stable and harmless. SiO₂ modification produces hydrophobic properties which increase corrosion resistance. One of the methods to make SiO₂ is sol-gel method. The advantages of sol-gel method are simple, affordable, capable of forming a film for attaching chemical properties, flexible for incorporation with other compounds and the coating can be applied in several ways, such as dip coating, spray coating, electrophoretic deposition (EPD), etc. As an anti-corrosion coating, products can be tested for their resistance by analyzing the corrosion rate. This paper reviews silica-based metal coatings as anti-corrosion. The scope of the discussion in this paper is the mechanism, fabrication route, application technique, characterization, and analysis of anti-corrosion ability by studying the corrosion rate of anti-corrosion silica-based coating products for metal substrates.

Abstract: In this paper a combination of colloidal silica and different gelling agents are studied in order to observe the effect of gelation rate on the formed sol-gel structure. Proper ratios of sol matrix materials and gelation agents were determined. Sets of samples based on these recipes were prepared with added filling material and tested for mechanical properties. Samples with added solution of NaCl gelling agent showed the highest flexural strength observed and also lower doses of this gelling agent are required for one of the studied sols which can positively effect the final price of product.

Abstract: Photocatalysts that can utilize sunlight energy have attracted attention. In this study, g-C₃N₄ and mesoporous SiO₂@TiO₂ particles were mixed by hydrothermal synthesis. g-C₃N₄ was made by a simple method of directly heating melamine. Mesoporous SiO₂@TiO₂ was prepared using the stover method. These two types of particles were then mixed by hydrothermal synthesis. Hydrothermal synthesis reduced the size of the g-C₃N₄ particles, and they bound more closely with the TiO₂ particles. The degradation of methylene blue dye by visible light was performed to evaluate the organic degradation of the mixed particles. In addition, the mixed particles were formed into a thin film by the spin-coating method. The film's methylene blue degradation performance and the film's power generation performance in a battery were evaluated. The film showed high convenience in the practical application of photocatalytic degradation of organic pollutants because it can be easily separated from the treated liquid after organic matter degradation.

Abstract: SiO₂ were successfully synthesized by sol–gel process via in-situ modification. The SiO₂ consists of two kinds of co-precursor namely raw material from quartz sand and methyltrimethoxysilane (MTMS) as main SiO₂ source. By introducing SiO₂ with different sizes of particle micro-submicron scale, it was suggested to construct hierarchical structure. The sample was characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) to analyze crystal structure, morphology of particles, and surface roughness of the samples. In this research, SiO₂ co-precursor from quartz sand were extraction and synthesis to be SiO₂ quartz (SQ) phase and SiO₂ amorphous (SA) phase respectively which is combine with SiO₂ based MTMS by sol–gel process via in-situ modification. Based on the results, it can be concluded that SiO₂ with high purity levels maintains its crystal structure even after in-situ modification, resulting in an increase in particle size to approximately 12-20 μm. SEM images showed that particle was irregular shape due to agglomeration which is SiO₂ based quartz sand stick by SiO₂ based MTMS. AFM showed the surface roughness of MTMS/SQ have a larger roughness than MTMS/SA with Sa 3.3 ± 0.8 nm and Sq 5.0 ± 1.0 nm. The formation of hierarchical structure layers based on SiO₂ has a promising potential for wide applications in various fields such as hydrophobic surface.

Abstract: The magnetic photocatalyst of CoZnFe₂O₄/SiO₂ nanoparticles has been synthesised to degrade methylene blue (MB) dye. The CoZnFe₂O₄ nanoparticles were prepared by co-precipitation method under mechanical stirring and coated with SiO₂ by stöber method using Na₂SiO₂ with various concentrations of 5%, 10%, 15%, 20%, 30%, and 50%. The properties of CoZnFe₂O₄/SiO₂ was confirmed by x-ray diffraction (XRD), Fourier transforms infrared (FTIR), vibrating sample magnetometer (VSM), and UV-Visible spectroscopy. XRD analysis revealed that CoZnFe₂O₄ had the spinel ferrite phase structure with crystalite size of 17.0 nm, and then after coating with SiO₂, the size became 17.1 nm. FTIR clearly show an M-O octahedral vibrational bond found with a wavelength of 378 cm^-1, O-Si-O, Si-OH, and Si-O-Fe at 1087, 794, and 570 cm^-1, respectively. The saturation magnetization (Ms) and coercivity of CoZnFe₂O₄/SiO₂ was 29.0 emu/g and 251.9 Oe, respectively. Furthermore, the results of UV-Visible data presented that the absorption edges CoZnFe₂O₄/SiO₂ in the range of 190 - 600 nm. The percentage of CoZnFe₂O₄ degradation is 88.4%, while after coted SiO₂ 50%, the degradation becomes 98.9%.

Abstract: The performance of the SiO₂ MOSFET-based absorber as a solution to arching within transmission lines (used for RF signal transportation) has been realized and analyzed at 28 GHz using the reflected signal from the R_X branch of 5G massive MIMO base station. The reflected signal from the receiver (R_X) branch of base stations may lead to interference, thus creating a performance reducing condition (arching) within the transmission lines. For optimum performance in the 5G regime, the SiO₂ MOSFET has been used to solve the problem of arching within the transmission line under large field intensities of a standing wave resulting from the impedance. The SiO₂ MOSFET-based absorber has been observed for a reflectivity of -79.5 dB and a rectification efficiency greater than 17 %