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Highly sensitive air stable easily processable gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors for multiparametric H <sub/>2</sub> S and NH <sub/>3</sub> real-time detection
摘要： A combination of low limit of detection, low power consumption and portability makes organic field-effect transistors (OFETs) chemical sensors promising for various applications in the areas of industrial safety control, food spoilage detection and medical diagnostics. However, the OFET sensors typically lack air stability and restoration capability at room temperature. Here we report on a new design of highly sensitive gas sensors based on Langmuir-Schaefer monolayer organic field-effect transistors (LS OFETs) prepared from organosilicon derivative of [1]benzothieno[3,2-b][1]-benzothiophene. The devices fabricated are able to operate in air and allows an ultrafast detection of different analytes at low concentrations down to tens ppb. The sensors are reusable and can be utilized in real-time air quality monitoring systems. We show that a direct current response of the LS OFET can be splitted into the alteration of various transistor parameters, responsible for the interactions with different toxic gases. The sensor response acquiring approach developed allows distinguishing two different gases, H2S and NH3, with a single sensing device. The results reported open new perspectives for the OFET-based gas-sensing technology and pave the way to easy detection of the other types of gases enabling the development of complex air analysis systems based on a single sensor.
关键词： Multiparametric detection,Sensing mechanism,Monolayer organic field-effect transistors,Langmuir-Schaefer monolayers,Chemical sensors
更新于2025-09-11 14:15:04
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Gas Sensing Performances of ZnO Hierarchical Structures for Detecting Dissolved Gases in Transformer Oil: A Mini Review
摘要： Power transformer is one of the critical and expensive apparatus in high voltage power system. Hence, using highly efficient gas sensors to real-time monitor the fault characteristic gases dissolved in transformer oil is in pressing need to ensure the smooth functionalization of the power system. Till date, as a semiconductor metal oxide, zinc oxide (ZnO) is considered as the promising resistive-type gas sensing material. However, the elevated operating temperature, slow response, poor selectivity and stability limit its extensive applications in the field of dissolved gases monitoring. In this respect, rigorous efforts have been made to offset the above-mentioned shortcomings by multiple strategies. In this review, we first introduce the various ZnO hierarchical structures which possess high surface areas and less aggregation, as well as their corresponding gas sensing performances. Then, the primary parameters (sensitivity, selectivity and stability) which affect the performances of ZnO hierarchical structures based gas sensors are discussed in detail. Much more attention is particularly paid to the improvement strategies of enhancing these parameters, mainly including surface modification, additive doping and ultraviolet (UV) light activation. We finally review gas sensing mechanism of ZnO hierarchical structure based gas sensor. Such a detailed study may open up an avenue to fabricate sensor which achieve high sensitivity, good selectivity and long-term stability, making it a promising candidate for transformer oil monitor.
关键词： ZnO,sensitivity,gas sensors,hierarchical structures,stability,gas sensing mechanism,selectivity
更新于2025-09-10 09:29:36
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Impact of TiO2 Nanotubes’ Morphology on the Photocatalytic Degradation of Simazine Pollutant
摘要： There are various approaches to enhancing the catalytic properties of TiO2, including modifying its morphology by altering the surface reactivity and surface area of the catalyst. In this study, the primary aim is to enhance the photocatalytic activity by changing the TiO2 nanotubes’ architecture. The highly ordered infrastructure is favorable for a better charge carrier transfer. It is well known that anodization affects TiO2 nanotubes’ structure by increasing the anodization duration which in turn in?uence the photocatalytic activity. The characterizations were conducted by FE-SEM (?end emission scanning electron microscopy), XRD (X-ray diffraction), RAMAN (Raman spectroscopy), EDX (Energy dispersive X-ray spectroscopy), UV-Vis (Ultraviolet visible spectroscopy) and LCMS/MS/MS (liquid chromatography mass spectroscopy). We found that the morphological structure is affected by the anodization duration according to FE-SEM. The photocatalytic degradation shows a photodegradation rate of k = 0.0104 min?1. It is also found that a mineralization of Simazine by our prepared TiO2 nanotubes leads to the formation of cyanuric acid. We propose three Simazine photodegradation pathways with several intermediates identi?ed.
关键词： Simazine,TiO2 nanotubes,anodization,photodegradation mechanism,photocatalytic,photocatalyst
更新于2025-09-10 09:29:36
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Analytical Study of Electron Mobility in Hemts Algan/Gan
摘要： The hetero junctions GaN based offer an excellent potential for power applications at high frequency. This is due to the important energy of the bandgap and high saturation velocity of electrons. The high mobility transistors (HEMT - High Electron Mobility Transistor) are based on the heterojunction AlGaN/GaN. Our work is the subject of an analytical study of the carrier mobility HEMTs AlGaN/GaN calculating Ionized impurities scattering, Residual impurities scattering, Interface roughness scattering, Alloy disorder scattering, dislocations scattering, Phonons and Dipoles taking into account the impact of technological parameters (doping, aluminium content) and geometric (thickness barrier, interface roughness). The results allowed us to take account of the variation of carrier density in the wells of 2D electronic gas.
关键词： HEMT,Mobility,Scattering mechanism,AlGaN/GaN heterojunction,2DEG
更新于2025-09-10 09:29:36
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Nucleation mechanism of metal-vapor atoms on photochromic diarylethene surface with a low glass transition temperature
摘要： Metal pattern formation on organic surfaces is essential in organic electronics. Selective metal-vapor deposition using photochromic diarylethene (DAE) is a promising method to prepare ?ne metal patterns by maskless evaporation. Metal-vapor atoms are adsorbed, di?used, and then desorbed from the colorless surface with a low glass transition temperature. We, however, found that metal deposition started at a speci?c time (deposition-threshold time, tth) even on the colorless surface by continuous evaporation. tth was investigated using a quartz crystal microbalance. We elucidated that metal-nucleation sites were generated by chemical reactions between metal atoms and surface DAE molecules. The number of nucleation sites increases during metal evaporation and when the sites are located in the di?usion range of surface metal atoms, metal-atom nucleation for ?lm-formation starts. This is the origin of tth. This result would provide important knowledge for the preparation of electrodes for organic devices based on selective metal-vapor deposition.
关键词： organic electronics,nucleation mechanism,photochromic diarylethene,quartz crystal microbalance,metal-vapor deposition
更新于2025-09-10 09:29:36
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Tri-core photonic crystal fiber based refractive index dual sensor for salinity and temperature detection
摘要： This article discusses the tri-core photonic crystal microstructure fiber for the process of simultaneous sensing for salinity and temperature of water substances. This kind of microstructure is preferred in many sensing application to scale the detection process in micrometer range. In this novel sensor, the sensitivity is calculated through coupling mechanism by tracking wavelength shift of various concentrations of salinity and temperature using finite element method. The sensible samples are in liquid and are infiltrated into the framed hollow cavity. Based on the coupling principle between silica substrate and the analyte material, the sense of the salt as well as temperature is obtained. Finally, it is noted that sensitivity of the salt level in water as 5404.9 nm/RIU for x polarization direction and 5674 nm/RIU for y polarization direction have been calculated with the temperature sensitivity of 4 nm/(cid:1)C in the same water substances.
关键词： photonic crystal fiber,finite element method,sensitivity and coupling mechanism
更新于2025-09-10 09:29:36
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[Springer Theses] CMOS-Compatible Key Engineering Devices for High-Speed Silicon-Based Optical Interconnections || Summary and Future Work
摘要： This dissertation mainly focuses on four important scientific problems in silicon photonics, i.e., silicon electro-optic modulator, advanced multiplexing mechanism, polarization controlling and fiber-to-chip coupling. It systematically puts forward the design theory of silicon electro-optic modulator, investigates advanced multiplexing mechanisms, studies polarization-controlling devices, and explores fiber-to-chip coupling techniques. The research demonstrates high-performance devices fabricated with commercial 130 nm CMOS process, including a high-speed carrier-depletion silicon electro-optic modulator, WDM devices, PDM devices, MDM devices, and ultra-compact polarization splitter-rotators. The work aims to contribute to the field of silicon photonics by providing CMOS-compatible solutions for high-speed silicon-based optical interconnections.
关键词： multiplexing mechanism,CMOS-compatible,fiber-to-chip coupling,polarization controlling,electro-optic modulator,silicon photonics
更新于2025-09-10 09:29:36
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Anthracene- and pyrene-bearing imidazoles as turn-on fluorescent chemosensor for aluminum ion in living cells
摘要： A newly designed 2-(2-Aminophenyl)-1H-benzimidazole integrated anthracene/pyrene derivatives as efficient chemosensors were synthesized. The probes N-(anthracen-9-ylmethylene)-2-(1H-benzo[d]imidazol-2-yl)aniline (ANP) and N-(pyren-1-ylmethylene)-2-(1H-benzo[d]imidazol-2-yl)-aniline (PYP) exhibited high selectivity and sensitivity towards Al3+ ion over other interfering and competing cations in aqueous solution. Job’s plot analysis reveals that the interaction of ANP/PYP with Al3+ was 1:1 binding stoichiometry. The detection limit of probes ANP and PYP for Al3+ ions were found to be 1.85 × 10-7 M and 1.08 × 10-7 M, respectively. The DFT/TD-DFT calculations have also been revealed that the ICT mechanism is responsible for the observed photophysical changes. Moreover, the probes ANP and PYP were applicable to image intracellular Al3+ ions in living cells via confocal fluorescence microscopy technique.
关键词： Pyrene,Al3+ imaging,ICT mechanism,Turn-on chemosensor,Anthracene
更新于2025-09-10 09:29:36
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Buffer Vertical Leakage Mechanism and Reliability of 200-mm GaN-on-SOI
摘要： A comprehensive study on buffer vertical leakage mechanism and buffer reliability of 200-mm GaN-on-SOI is conducted in this paper. The buffer vertical leakage current versus bias is found to sequentially comprise three ranges of low-field leakage, variable-range hopping, and breakdown. The low-field leakage increase at high temperatures has been proven to be dominated by surface leakage. The stressing voltages of buffer time-dependent breakdown (TDB) measurements have a significant impact on shape factor β. Stress-induced leakage current is observed in the wear-out phase of the TDB curves. Stress-and-sense measurements in this phase indicate that defects are generated probably around the threading dislocations, where more localized Joule heating and more defects are created by a positive feedback, and finally, the buffer breaks down due to thermal runway. At last, based on the Weibull plot and E-model, the operating voltage is extrapolated to be 470 V corresponding to an expected lifetime of 10 years at 175 °C, with area scaling to the drain terminal of a 150-mm power transistor and failures scaling to 0.01%. The qualification of GaN-on-SOI is crucial for future 200-V GaN power integrated circuit on this platform.
关键词： GaN-on-SOI,time-dependent breakdown (TDB),leakage mechanism,Buffer reliability
更新于2025-09-10 09:29:36
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pH-Dependent Degradation of Layered Black Phosphorus: Essential Role of Hydroxide Ions
摘要： The practical application of layered black phosphorus (LBP) was challenged by fast decomposition in the presence of H2O and/or O2, and the role of H2O was highly controversial. Herein, we proposed a hydroxide ion (OH-)-initiated degradation mechanism for LBP to elucidate the role of H2O. We found that LBP degraded faster in alkaline solutions than in neutral or acidic solutions with or without O2. Degradation rates of LBP increased linearly from pH 4 to 10. Density functional theory calculations showed that OH- initiated the decomposition of LBP through breaking the P–P bond and forming a P–O bond. The detection of hypophosphite, generated from OH- reacting with P atoms, confirmed the hypothesis. Protons acted in a way distinctive from OH-, by inducing deposition/aggregation or forming a cation-π layer to protect LBP from degradation. This work revealed the exact degradation mechanism of LBP to facilitate the development of effective stabilization technologies.
关键词： Degradation mechanism,Hydroxide ion,Nanostructures,Density functional calculations,Black phosphorus
更新于2025-09-10 09:29:36