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- 实验方案
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Substrate-Wide Confined Shear Alignment of Carbon Nanotubes for Thin Film Transistors
摘要： To exploit their charge transport properties in transistors, semiconducting carbon nanotubes must be assembled into aligned arrays comprised of individualized nanotubes at optimal packing densities. However, achieving this control on the wafer-scale is challenging. Here, solution-based shear in substrate-wide, confined channels is investigated to deposit continuous films of well-aligned, individualized, semiconducting nanotubes. Polymer-wrapped nanotubes in organic ink are forced through sub-mm tall channels, generating shear up to 10 000 s?1 uniformly aligning nanotubes across substrates. The ink volume and concentration, channel height, and shear rate dependencies are elucidated. Optimized conditions enable alignment within a ±32° window, at 50 nanotubes μm?1, on 10 × 10 cm2 substrates. Transistors (channel length of 1–5 μm) are fabricated parallel and perpendicular to the alignment. The parallel transistors perform with 7× faster charge carrier mobility (101 and 49 cm2 V?1 s?1 assuming array and parallel-plate capacitances, respectively) with high on/off ratio of 105. The spatial uniformity varies ±10% in density, ±2° in alignment, and ±7% in mobility. Deposition occurs within seconds per wafer, and further substrate scaling is viable. Compared to random networks, aligned nanotube films promise to be a superior platform for applications including sensors, flexible/stretchable electronics, and light emitting and harvesting devices.
关键词： electronics,alignment,mobility,field-effect transistors,semiconductors
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
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Design of visible-light photocatalysts by coupling of inorganic semiconductors
摘要： The design of advanced photocatalytic systems, effectively working under visible-light, is essential for practical application of photocatalysts in removing environmental pollutants. To achieve high efficiency, the required properties for the photocatalysts are profound solar light absorption in the visible-range, efficient charge-separation, suitable energy band locations for redox reactions, and extended photostability. As a single semiconductor-based photocatalyst cannot satisfy all of these requirements, a potential strategy will be construction of coupled structures between two or more semiconductors. In the present study, we explore various types of photocatalytic systems constructed by coupling semiconductors and their working mechanisms. When two narrow bandgap semiconductors (NBSs) absorbing visible-light are coupled to form heterojunction structures, they can be classified as p-n junction or Z-scheme systems, according to the charge-flow pathway between the two semiconductors. When a NBS that absorbs visible-light is coupled with a wide bandgap semiconductor (WBS) functioning as the main photocatalyst, the fabricated catalytic systems can be classified as Type-A or Type-B heterojunction systems dependent on their relative energy band locations. Herein various semiconductor composites reported to be visible-light photocatalysts in the literature are classified using these categories, and their photocatalytic mechanisms, including charge-flow pathways, are discussed in depth. In addition, recent progress and future perspectives for heterojunction systems are reviewed and discussed.
关键词： Oxidation reaction,Coupling of semiconductors,Type-B heterojunction,Heterojunction,Visible light,Photocatalyst
更新于2025-09-09 09:28:46
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TiO2@g-C3N4 heterojunction with directional charge migration behavior for photodegradation of tetracycline antibiotics
摘要： The performance of semiconductor photocatalysts in organic contaminants degradation is strongly influenced by the structure-related charge separation behavior. Hence, titanium dioxide (TiO2) nanowire, which is efficient in directional migration of photocarriers, is prepared and employed as the carrier for the in situ growth of discrete graphite carbon nitride (g-C3N4) to form a compact and high-reactive heterojunction photocatalyst. The structures and properties of the samples are systematically characterized and discussed. The experimental results indicate that the tetracycline photodegradation efficiency obtained by employing TiO2@g-C3N4 as the photocatalyst is improved by 126% and 75%, respectively, compared to that using TiO2 nanowire and bulk g-C3N4. This work highlights that precisely controlling the microstructure and charge separation behavior is critical for preparing high-reactive photocatalysts.
关键词： Composite materials,Semiconductors,Heterojunction,g-C3N4,Photocatalysis
更新于2025-09-09 09:28:46
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Stochastic Resonance in Bioinspired Electronic Device Using Polymer Field Effect Transistors
摘要： Stochastic resonance (SR) phenomenon is emerged in organic field effect transistors (OFETs) using π-conjugated polymer, where application of external noise to the OFET system enhances signal/information processing performance which is often found in biological systems. The channel conductivity of the OFET is slightly increased by spin-coating using heated semiconductor polymer solution with heated glass substrate. In order to improve frequency responses of OFET, optimal width of the gate electrode is explored. Furthermore, it turns out that scratching and removing semiconductor film outside the source-drain electrodes and the channel enhances the On-Off current ratio of the device. These fabrication processes lead to steeper nonlinearity on the IDS vs. VGS curve, resulting in emergence of SR, which is fingerprinted in increase of correlation value between input and output signals with increase of intensity of external noise.
关键词： Stochastic resonance,Polymer thin films,Organic semiconductors,Bioinspiration,Field effect transistors
更新于2025-09-09 09:28:46
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Desorption of Te capping layer from ZnTe (100): Auger spectroscopy, low-energy electron diffraction and scanning tunneling microscopy
摘要： The influence of the annealing temperature to desorb a protective Te capping layer of the zinc telluride (ZnTe (100)) surface was investigated. The surface reconstruction of the ZnTe (100) upon the removal of a Te capping layer grown by the molecular beam epitaxy was characterized by different methods. Auger spectroscopy brought out the chemical composition of the surface before and after annealing; the Low-energy electron diffraction (LEED) gave information about the crystallographic structure. The surface crystallographic configurations of tellurium Te (c (2x2)) and Te (c (2x1)) are confirmed by scanning tunneling microscopy (STM). Such a study reveals a phase transition from a rich-Te to a poor-Te surface as the annealing temperature increases.
关键词： structural properties,optoelectronics,Zinc Tellure,semiconductors,solar cells
更新于2025-09-09 09:28:46
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Gallium Oxide || Synthesis, optical characterization, and environmental applications of β-Ga2O3 nanowires
摘要： In this chapter, we present the synthesis, optical characterization, and environmental applications of the β-Ga2O3 nanowires. The gap-state and near-band-edge transitions of β-Ga2O3 nanowires were identified and studied. The defects states play an important role in their optical emission and photocatalytic property. Owing to its various interesting properties such as wide bandgap, chemical and thermal stability, robust defect states, large surface to volume ratios, β-Ga2O3 nanowires are very promising in potential applications in optoelectronic, environmental applications, and fundamental research in the future.
关键词： wide-band-gap semiconductors,synthesis,optical characterization,photocatalytic activity,β-Ga2O3 nanowires,environmental applications
更新于2025-09-09 09:28:46
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Gallium Oxide || Electron paramagnetic resonance (EPR) from β-Ga2O3 crystals
摘要： Electron paramagnetic resonance (EPR) is often used to identify and characterize defects and impurities having unpaired spins in semiconductors and insulators [1–4]. Examples include donors, acceptors, vacancies, interstitials, antisites, small polarons, transition-metal ions, and rare-earth ions. Simply stated, an EPR spectrum represents the absorption of microwaves at discrete values of magnetic field. This allows the energy-level scheme of the unpaired spin system to be determined. The importance of EPR arises from its high sensitivity and high resolution. Depending on the line widths, concentrations of defects as low as a few parts per billion can be easily observed. Each paramagnetic defect has a unique EPR spectrum that reflects its g matrix and hyperfine matrices, as well as the zero-field splittings when S is greater than 1/2. Once the identity of the responsible defect has been established, a spectrum can be used to compare concentrations of the defect in different samples and also to monitor changes in the concentration of the defect during photoexcitations and thermal anneals.
关键词： Electron paramagnetic resonance,β-Ga2O3,defects,semiconductors,insulators,impurities
更新于2025-09-09 09:28:46
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Gallium Oxide || Hydrogen in Ga2O3
摘要： Semiconductors with bandgaps larger than the 3.4 eV bandgap of GaN are emerging as a new class of ultrawide-bandgap (UWBG) electronic materials [1–5]. In spite of the promising applications that are possible for UWBG materials, an understanding of their fundamental properties is at an early stage of development. The focus of this chapter is the hydrogen impurity and its interactions with other defects in β-Ga2O3, a transparent conducting oxide with an ultrawide bandgap of 4.9 eV [6–9]. (It is the most thermally stable monoclinic β phase of Ga2O3 to which we refer throughout this chapter.)
关键词： transparent conducting oxides,Hydrogen,defects,ultrawide-bandgap semiconductors,Ga2O3
更新于2025-09-09 09:28:46
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Gallium Oxide || Radiation damage in Ga2O3
摘要： β-Ga2O3 has a large bandgap of approximately 4.9 eV and an estimated critical electric field (EC) strength of 8 MV/cm. The large bandgap of β-Ga2O3 allows high-temperature device operation and this large critical field allows high-voltage operation (relative to maximum breakdown) and the most common device structure reported to date has been Schottky rectifiers. This material also has potential in devices with low power loss during high-frequency switching in the GHz regime. Similarly, Ga2O3-based photodetectors are attracting interest for their promise as truly solar-blind deep ultraviolet (UV) photodetectors exhibiting cut-off wavelengths below 280 nm. These would have applications in detection of UV wavelengths for military applications, air purification, space communication, ozone-layer monitoring, and flame sensing.
关键词： β-Ga2O3,photodetectors,radiation damage,Schottky rectifiers,wide bandgap semiconductors
更新于2025-09-09 09:28:46