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Pressure and Temperature Dependence of Field-Induced Oscillation in Two-Terminal Device Based on Vanadium Dioxide Thin Film
摘要： In this paper, we investigated the pressure and temperature dependence of the frequency and amplitude of the ?eld-induced oscillation created in a two-terminal device based on a vanadium dioxide (cid:2) thin ?lm. First, a simple oscillation circuit was constructed using a VO2-based two-terminal (VO2 device, a standard resistor, and a DC power supply. Then, the frequency and amplitude variation of the ?eld-induced oscillation was observed for pressure changes applied to the VO2 device in a pressure chamber. This variation of the oscillation characteristics was also examined for ambient temperature changes applied to the VO2 device using a plate heater. When the chamber pressure increased from 0 to 5 MPa with a step of 1 MPa at 25 (cid:3)C, the oscillation frequency increased from ～592 to ～739 kHz, and the oscillation amplitude decreased from ～12.60 to ～11.40 V. Similarly, when the heater temperature increased from 25 to 50 (cid:3)C (step: 5 (cid:3)C) without applied pressure, the oscillation frequency increased from ～592 to ～819 kHz, and the oscillation amplitude decreased from ～12.60 to ～7.16 V. Owing to linear pressure and temperature responses of the VO2 oscillation, the pressure and temperature sensitivities of the oscillation frequency and amplitude could be obtained as four different constant coef?cients from the measurement results. These coef?cients can be directly utilized for simultaneously measuring pressure and temperature variation applied to the VO2 device, which can be bene?cially applied to localized temperature and pressure sensing at a very small area less than 1 mm2.
关键词： Vanadium Dioxide,Thin Film,Sensor,Field-Induced Oscillation
更新于2025-09-09 09:28:46
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Growth of 1T’ MoTe <sub/>2</sub> by Thermally-Assisted Conversion of Electrodeposited Tellurium Films
摘要： Molybdenum ditelluride (MoTe2) is a transition metal dichalcogenide (TMD) which has two phases stable under ambient conditions, a semiconducting (2H) and semimetallic (1T’) phase. Despite a host of interesting properties and potential applications, MoTe2 is one of the less-studied TMDs, perhaps due its relatively-low abundance in nature or challenges associated with its synthesis, such as the toxicity of most precursors. In this report, we describe the fabrication of thin films of phase-pure 1T’ MoTe2 using pre-deposited molybdenum and electrodeposited tellurium layers, at the relatively low temperature of 450?C. This method allows control over film geometry and over the tellurium concentration during the conversion. The MoTe2 films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy and electron microscopies. When applied as a catalyst for the hydrogen evolution reaction, the films display promising initial results. The MoTe2 films have a Tafel slope of below 70 mV dec-1 and compare favorably with other MoTe2 catalysts reported in the literature, especially considering the inherently-scalable fabrication method. The variation in electrocatalytic behavior with thickness and morphology of the films is also investigated.
关键词： 1T’ phase,thin-film,hydrogen evolution reaction,Raman spectroscopy,MoTe2,electrocatalysis
更新于2025-09-09 09:28:46
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Manipulating and monitoring nanoparticles in micellar thin film superstructures
摘要： Understanding the dynamics of discrete self-assembled structures under influence of external triggers is of interest to harvest the potential of nano- and mesoscale materials. In particular, controlling the hierarchical organization of (macro)molecular and nanoparticle building blocks in monolayer superstructures is of paramount importance for tuning properties and characteristics. Here we show how the electron beam in cryo-transmission electron microscopy can be exploited to induce and follow local migration of building blocks and global migration of micellar aggregates inside micrometer-sized superstructures. We employ stroboscopic exposure to heat up and convert the vitrified superstructure into a liquid-like thin film under cryogenic conditions, resulting in controlled evaporation of water that finally leads to rupture of the micelle-containing superstructure. Micelle-embedded nanoparticles prove a powerful tool to study the complex hierarchically built-up superstructures, and to visualize both global movement of individual dendrimicelles and local migration of nanoparticles inside the micellar core during the exposure series.
关键词： cryo-transmission electron microscopy,self-assembly,nanoparticles,hierarchical organization,micellar thin film
更新于2025-09-09 09:28:46
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Influence of Yttrium Dopant on the Structure and Electrical Conductivity of Potassium Sodium Niobate Thin Films
摘要： KNN thin films with diverse yttrium concentration (mol % = 0, 0.1, 0.3, 0.5, 0.7 and 0.9) were fabricated using sol-gel spin coating technique. Doped KNN revealed that Y3+ was successfully doped into the ABO3 perovskite lattice without changing the phase formation of KNN. The thickness of the deposited layer of KNN produced with increasing dopant concentration was determined to be 200 nm with dense and well-defined grains. Afterwards, the vibrational bonding and conductivity of KNN films with diverse yttrium concentration were identified according to the charge compensation mechanism. At high dopant concentration of > 0.5 mol %, O-Nb-O bonding was asymmetric and became distorted due to B-site occupancy by yttrium dopant. Further investigation revealed that charge compensation mechanism was shifted by increasing doping concentration. As a result, yttrium-doped KNN became semi-conductive at low yttrium concentration. Meanwhile, at high concentration, yttrium-doped KNN became an insulator and underwent ionic compensation.
关键词： yttrium,thin film,doped,structural,KNN,conductivity
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Shenzhen (2018.6.6-2018.6.8)] 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Dynamic Threshold Voltage Modulation in Double-Gate Indium-Gallium-Zinc Oxide Thin-Film Transistors: Influence of the Active Layer Thickness
摘要： We investigated the effect of active layer thickness on dynamic threshold voltage (VTH) operation for double-gate (DG) (a-IGZO) thin-film transistors (TFTs). It is found that with 80 nm a-IGZO layer, by adjusting top gate (TG) biases from negative to positive, the bottom gate (BG)-sweep TFTs show a VTH dependence on TG bias with two linear relationships, and subthreshold swing (SS) varies with different TG biases. In contrast, with thinner (20 nm) a-IGZO layer, VTH of the BG-sweep TFTs is linearly modulated with a single slope, and no obvious SS change is observed.
关键词： Thin-film transistors (TFTs),amorphous indium-gallium-zinc-oxide (a-IGZO),double-gate
更新于2025-09-09 09:28:46
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Compared with a-Fe2O3 and ZnxFe3-XO4 Thin Films Grown by Chemical Spray Pyrolysis
摘要： This work describes hematite (a-Fe2O3) and ZnxFe3-XO4 thin films prepared by Chemical Spray Pyrolysis (CSP) method. CSP method allows an optimal control of stoichiometry and impurity incorporation, hematite films modified with Zn2+ was also prepared. Moreover, the most attracting characteristics of the hematite are its stability in neutral and basic solutions, abundance and band gap energy (2.0–2.2 eV) which permits it to absorb approximately 40% of the incident solar spectrum on earth. Nevertheless, the performance of hematite electrodes for water oxidation is restricted by their poor charge transport properties. Hematite has low conductivity and low charge-carrier mobility. In addition, the photoexcited electron–hole pairs have short life time (~10-12 s), which makes the hole diffusion length to be also short (2–4 nm). The charge transport properties of hematite can be improved by dopping. We demonstrated to increase the conductivity of hematite by dopping it with metal cations with 2+ charges which improved the photocatalytic properties. Doping with metal cations with 2+ charges has also brought good photoelectrochemical results. So we iron oxide and Zn-doped iron oxide compounds have been investigated. The structural, optical and magnetic properties of a-Fe2O3 and ZnxFe3-xO4 compounds have been extensively investigated. XRD, XPS, Raman, FE-SEM and AFM techniques have been used for structural analysis; Absorption technique has been used for optical properties; Hall and Vibrating Sample Magnetometer (VSM) techniques have been used for magnetic properties.
关键词： Hematite,Thin film,Photoelectrochemical (PEC),Zn-doped iron oxide
更新于2025-09-09 09:28:46
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Novel anti-ultraviolet performances of thin films polyurethane containing nano-mixed oxides CeO <sub/>2</sub> -TiO <sub/>2</sub>
摘要： The nano-mixed oxides CeO2-TiO2 was synthesized by gel combustion method using polyvinyl alcohol as fuel and mixtures of titanium trichloride and cerium(IV) nitrate at a relatively low calcination temperature of 550°C for 2 h. The prepared CeO2-TiO2 nanoparticles with a specific area of 65.70 m2 g-1 were dispersed in polyurethane matrix in different concentration conditions from 0.0 to 1.5 wt% to study ultraviolet durability following HONDA HES D 6501-97 standards. After 400 h of testing in the QUV accelerate weathering tester, the thin film containing 1 wt% CeO2-TiO2 nano-mixed oxides has presented the noticeable capacity for absorbing ultraviolet light by only 6.8 g.u change in specular gloss at 60° and DE = 3.66 in color difference.
关键词： hybrid material,thin film,CeO2-TiO2,nano-mixed oxides,polyurethane,anti-ultraviolet
更新于2025-09-09 09:28:46
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Effects of post-deposition plasma treatments on stability of amorphous InGaZnO <i> <sub/>x</sub></i> thin-film transistors prepared with plasma-assisted reactive magnetron sputtering
摘要： Effects of post-deposition plasma treatments on the stability of amorphous InGaZnOx thin-film transistors (TFTs) prepared with plasma-assisted reactive magnetron sputtering were investigated. The temporal evolution in the electrical characteristics of as-deposited IGZO TFT and post plasma treated IGZO TFT that passed over 400 d after fabrication and were kept under 40% humidity at room temperature were measured, resulting in which no change in the electrical characteristics of post plasma treated IGZO TFT with mobility of 40 cm2 V?1 s?1 were observed. Positive-current-bias instability in post plasma treated IGZO TFTs was examined together with as-deposited IGZO TFTs. The results indicated that the stabilities of electrical characteristics caused by the positive bias stress is primarily attributed to defects in the bulk a-IGZO region for as-deposited IGZO TFTs. The stabilities of electrical characteristics in post plasma treated IGZO TFTs were considerably improved compared to that of as-deposited IGZO TFTs. From these results, it was shown that the post plasma treatment is considered to be effective for improving the stability of IGZO TFTs as well as conventional thermal annealing.
关键词： post-deposition plasma treatments,stability,plasma-assisted reactive magnetron sputtering,amorphous InGaZnOx,thin-film transistors
更新于2025-09-09 09:28:46
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Studies on zinc oxide thin films by chemical spray pyrolysis technique
摘要： Zinc oxide (ZnO) thin films were deposited by chemical spray pyrolysis (CSP) technique using zinc acetate dihydrate solutions on microscopic glass substrates by varying the precursor concentration. The prepared films were characterized structurally and optically, using the powder X-ray diffraction (XRD) and UV analysis and Photoluminescence analysis. Crystallographic properties were analyzed through powder XRD. The XRD patterns shows a hexagonal structure with c-axis orientation (0 0 2) on self texturing phenomenon. Optical transmittance properties of the optimized ZnO thin films were investigated by using UV-Vis spectroscopy. The optical studies predicated a maximum transmittance in the range of above 70% with direct band gap values in the range of 2.9 to 3.2eV for the zinc oxide thin films. Under excitation of 300 nm radiations, sharp deep level emission peak at 2.506 eV dominates the photoluminescence spectra with weak deep level and near band edge emission peak at 3.026 and 3.427 eV respectively.
关键词： Photoluminescence,Transparent conducting oxide (TCO),UV-Vis,Zinc Oxide thin film,CSP technique,X-ray diffraction (XRD)
更新于2025-09-09 09:28:46
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Boosting Direct X-Ray Detection in Organic Thin Films by Small Molecules Tailoring
摘要： The attention focused on the application of organic electronics for the detection of ionizing radiation is rapidly growing among the international scientific community, due to the great potential of organic technology to enable large-area conformable sensor panels. However, high-energy photon absorption is challenging as organic materials are constituted of atoms with low atomic numbers. Here it is reported how, by synthesizing new solution-processable organic molecules derived from 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-pentacene) and 2,8-difluoro-5,11-bis(triethylsilylethynyl)anthradithiophene, with Ge-substitution in place of the Si atoms to increase the material atomic number, it is possible to boost the X-ray detection performance of organic thin films on flexible plastic substrates. Bis(triisopropylgermylethynyl)-pentacene based flexible organic thin film transistors show high electrical performance with higher mobility (0.4 cm2 V?1 s?1) and enhanced X-ray sensitivity, up to 9.0 × 105 μC Gy?1 cm?3, with respect to TIPS-pentacene-based detectors. Moreover, similar results are obtained for 5,11-bis(triethylgermylethynyl)anthradithiophene devices, confirming that the proposed strategy, that is, increasing the atomic number of organic molecules by chemical tailoring to improve X-ray sensitivity, can be generalized to organic thin film detectors, combining high X-ray absorption, mechanical flexibility, and large-area processing.
关键词： organic X-ray detectors,thin film transistors,TIPS-pentacene,TIPGe-pentacene
更新于2025-09-09 09:28:46