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- 2018
- interdigital resonator
- microwave gas sensor
- PSE-coated
- Optoelectronic Information Science and Engineering
- King Mongkut’s University of Technology North Bangkok
- Rajamangala University of Technology Suvarnabhumi
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SiO <sub/>2</sub> etch characteristics and environmental impact of Ar/C <sub/>3</sub> F <sub/>6</sub> O chemistry
摘要： Perfluorocarbon gases are commonly used for nanoscale etching in semiconductor processing; however, they have the disadvantages of a long lifetime and inducing global warming effects when released into the atmosphere. In this study, the SiO2 etch characteristics and global warming effects of C3F6O gas chemistry, which has a low global warming potential, were compared with those of C4F8 chemistry, which is commonly used in semiconductor processing. Using Ar/C3F6O, the SiO2 etch rate was higher and the etch selectivity of SiO2 over the amorphous carbon hardmask layer was lower than the etch rate and etch selectivity using Ar/C4F8/O2, with all other etch conditions the same. Furthermore, using Ar/C3F6O exhibited more anisotropic SiO2 etch profiles by suppressing the bowing, narrowing, and necking effects compared to the etch profiles using Ar/C4F8/O2. The global warming effects were evaluated by calculating the million metric ton carbon equivalents (MMTCEs) from the volumetric concentrations of the emitted by-product species and process gases, and the results showed that, in the optimized conditions, Ar/C3F6O exhibited a lower environmental impact with an MMTCE of <24% than that of Ar/C4F8/O2. Therefore, it is suggested that the Ar/C3F6O gas mixture is a potential replacement for Ar/C4F8/O2 because of its lower MMTCE and acceptable SiO2 etch characteristics.
关键词： C4F8 chemistry,C3F6O gas chemistry,SiO2 etch characteristics,semiconductor processing,global warming effects
更新于2025-09-09 09:28:46
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Normal mode splitting in quantum degenerate Fermi gas in nano-cavity
摘要： We report the normal mode splitting in the fermionic displacement spectrum as a single mode light field interacts with a mechanical mode of ultra-cold quantum degenerate Fermi gas trapped inside a Fabry–Pérot cavity in the strong coupling regime. We explain the normal mode splitting in the outgoing field of the cavity field and in the field quadratures as well. As a function of system parameters, such as coupling strength between fermionic mode and field mode, number of fermionic atoms, cavity decay rate and fluctuations associated with the fermionic mode we explain the phenomenon of normal mode splitting. The low-lying fermions ensemble displays a collective density oscillation associated with particle-hole excitations, which interacts with cavity light field and lead to the observation of NMS in the fermion quadratures and light modes. The numerical results based on the present day laboratory experiments agree with the obtained analytical results.
关键词： Fabry–Pérot cavity,quantum degenerate Fermi gas,Normal mode splitting,fermionic displacement spectrum,strong coupling regime
更新于2025-09-09 09:28:46
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Nanocavities cause a stir
摘要： Reactions between gases and liquids are important in industry but are typically slow and difficult to monitor in situ. Elevated temperatures and pressures are often required to increase the efficiency of reactions between immiscible gases and liquids. Now, reporting in Angewandte Chemie International Edition, Xing Yi Ling and colleagues introduce a platform composed of an array of solid nanoparticles coated in a metal–organic framework (MOF) that substantially increases gas–liquid reaction efficiency owing to the formation of interfacial nanocavities. The platform can also be adapted for the in situ monitoring of reactions.
关键词： nanocavities,gas–liquid reactions,metal–organic frameworks,in situ monitoring,solid@MOF
更新于2025-09-09 09:28:46
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CuO Thin Films Functionalized with Gold Nanoparticles for Conductometric Carbon Dioxide Gas Sensing
摘要： Metal oxides (MOx) are a well-established material for gas sensing. MOx-based gas sensors are sensitive to a wide variety of gases. Furthermore, these materials can be applied for the fabrication of low-cost and -power consumption devices in mass production. The market of carbon dioxide (CO2) gas sensors is mainly dominated by infra-red (IR)-based gas sensors. Only a few MOx materials show a sensitivity to CO2 and so far, none of these materials have been integrated on CMOS platforms suitable for mass production. In this work, we report a cupric oxide (CuO) thin film-based gas sensor functionalized with gold (Au) nanoparticles, which exhibits exceptional sensitivity to CO2. The CuO-based gas sensors are fabricated by electron beam lithography, thermal evaporation and lift-off process to form patterned copper (Cu) structures. These structures are thermally oxidized to form a continuous CuO film. Gold nanoparticles are drop-coated on the CuO thin films to enhance their sensitivity towards CO2. The CuO thin films fabricated by this method are already sensitive to CO2; however, the functionalization of the CuO film strongly increases the sensitivity of the base material. Compared to the pristine CuO thin film the Au functionalized CuO film shows at equal operation temperatures (300 ?C) an increase of sensitivity towards the same gas concentration (e.g., 2000 ppm CO2) by a factor of 13. The process flow used to fabricate Au functionalized CuO gas sensors can be applied on CMOS platforms in specific post processing steps.
关键词： metal oxides,CMOS integration,CO2,gas sensors,CuO
更新于2025-09-09 09:28:46
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High resolution TPC based on optically readout GEM
摘要： Large granularity and high sensitivity commercial CMOS readout systems open the possibility of developing particle detectors with very interesting performance for different applications, from the search of rare and exotic events, such as dark matter directional candidates, to high quality neutron/ion/hadron beam monitor, mainly for medical applications. The gas scintillation mechanism was exploited for starting an R&D on large TPC-based detector, equipped with a Triple GEM amplification stage optically readout. By this approach, a 7 litre sensitive volume detector was built and tested. Space resolutions of 35 μm on the GEM plane (X,Y) and 100 μm on Z and energy measurements with a precision of about 25% were obtained. Analysis of the track shapes provides precious information allowing very good particle discrimination.
关键词： Micro-pattern Gas Detectors,GEM,Tracking detectors
更新于2025-09-09 09:28:46
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ZnO Nanostructure Based QCM Sensor to Detect Ethanol at Room Temperature Fabricated by All Wet Process
摘要： QCM is one of major sensing methods for volatile organic compounds (VOC) at room temperature. Nanostructure is effective to increase the sensitivity because of its large surface area. We introduced ZnO nanostructure to detect ethanol gas. ZnO nanostructure was fabricated by all wet process such as electrodeposition and chemical bath deposition (CBD). In this case, seed layer was obtained by electrodeposition, and nanostructure was formed by the CBD. The thickness of seed layer was controllable by charge amount on the electrodeposition, and that of nanostructure was controllable by deposition time on the CBD. As the results, the sensitivity increased with the thickness of the seed layer when the deposition time on CBD was set as 30 min. These results indicate that we can obtain high sensitive VOC sensor by using all wet process which is fit to large scale production with cost-effective.
关键词： nanostructure,QCM,gas sensing
更新于2025-09-09 09:28:46
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Planar Microstrip Ring Resonator Structure for Gas Sensing and Humidity Sensing Purposes
摘要： A planar microstrip ring resonator structure on alumina was developed. It was covered with a zeolite film. The device was successfully operated at around 8.5 GHz at room temperature as a humidity sensor. In the next step, an additional planar heater will be included on the reverse side of the resonator structure to allow for testing of gas sensitive materials under sensor conditions.
关键词： zeolite in operando spectroscopy,radio frequency gas sensing (RF),microwave sensors
更新于2025-09-09 09:28:46
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Low-temperature silicon oxidation using oxidizing radicals produced by catalytic decomposition of H <sub/>2</sub> O/H <sub/>2</sub> on heated tungsten wire
摘要： The surface oxidization of Si(100) substrates by oxidizing species generated by the catalytic decomposition of H2O precursors on a heated tungsten wire in a mixed H2O/H2 gas atmosphere was investigated. The formation of Si oxide layers was realized at stage temperatures of not more than 350 °C. From X-ray photoelectron spectroscopy measurements, their thicknesses were estimated to be 1–2 nm. In the tungsten wire temperature range from 1000 to 1450 °C, the oxidation of the wire was suppressed at H2O/H2 ratios of not more than 0.2%, which hardly caused tungsten contamination of the oxide layers.
关键词： catalytic decomposition,silicon oxidation,tungsten wire,oxidizing radicals,H2O/H2 gas atmosphere
更新于2025-09-09 09:28:46
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Case Studies of the Impact of Orbital Sampling on Stratospheric Trend Detection and Derivation of Tropical Vertical Velocities: Solar Occultation versus Limb Emission Sounding
摘要： This study investigates the representativeness of two types of orbital sampling applied to stratospheric temperature and trace gas fields. Model fields are sampled using real sampling patterns from the Aura Microwave Limb Sounder (MLS), the HALogen Occultation Experiment (HALOE) and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS). The MLS sampling acts as a proxy for a dense uniform sampling pattern typical of limb emission sounders, while HALOE and ACE-FTS represent coarse non-uniform sampling patterns characteristic of solar occultation instruments. First, this study revisits the impact of sampling patterns in terms of the sampling bias, as previous studies have done. Then, it quantifies the impact of different sampling patterns on the estimation of trends and their associated detectability. In general, we find that coarse non-uniform sampling patterns may introduce non-negligible errors in the inferred magnitude of temperature and trace gas trends and necessitate considerably longer records for their definitive detection. Lastly, we explore the impact of these sampling patterns on tropical vertical velocities derived from stratospheric water vapor measurements. We find that coarse non-uniform sampling may lead to a biased depiction of the tropical vertical velocities and, hence, to a biased estimation of the impact of the mechanisms that modulate these velocities. These case studies suggest that dense uniform sampling such as that available from limb emission sounders provides much greater fidelity in detecting signals of stratospheric change (for example, fingerprints of greenhouse gas warming and stratospheric ozone recovery) than coarse non-uniform sampling such as that of solar occultation instruments.
关键词： Atmospheric Chemistry Experiment Fourier Transform Spectrometer,trace gas fields,HALogen Occultation Experiment,Aura Microwave Limb Sounder,orbital sampling,stratospheric temperature,tropical vertical velocities,trend detection
更新于2025-09-09 09:28:46
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[Energy, Environment, and Sustainability] Sensors for Automotive and Aerospace Applications || Leakage Monitoring in Inflatable Space Antennas: A Perspective to Sensitive Detection of Helium and Nitrogen Gases
摘要： In?atable space structures have become an important part of space explorations due to their lightweight, simpler design, low cost, and fewer parts. These structures include antennas, solar arrays, solar concentrators, re?ectors, etc. These structures are made of ?exible polymers which can be folded and easily carried with spacecraft due to their small volume and weight. Structures, when reaching their destination, are in?ated through internal pressurization to achieve desired structural integrity. In space, these structures are subjected to very harsh environment such as high radiation levels, structural vibrations, and micrometeoroid bombardments. The polymeric material used to fabricate these structures is susceptible to degradation under these harsh conditions. These structures are prone to lose their structural integrity over long-term degradation of the material. The most common problem associated with in?ated space antennas is leakage of in?ated gas. Hence, the health monitoring of these structures becomes crucial to avoid structural failure due to leakages which may cause loss of information, accuracy, and money. Gas sensors are used to detect leakages in these structures. A mixture of helium (He) and nitrogen (N2) is used as in?ating gas in space antennas. Helium is the lightest gas after hydrogen and has chemically inert, non?ammable nature which makes it an ideal in?ating gas. However, the detection of He leakages is very dif?cult because of its nonreactive behavior with chemical species. Metal oxide based semiconducting (MOSs) materials are widely used sensing element for detection of various gases. Although it is very dif?cult to ?nd out He gas leakages, vanadium pentoxide (V2O5) can detect even a small concentration of He through resistive changes. In this chapter, we will discuss the requirement of leakage monitoring system for in?atable space antennas and He gas sensing properties of V2O5 semiconducting material.
关键词： Helium detection,Metal oxide semiconductors,Gas sensors,In?atable space structures
更新于2025-09-09 09:28:46