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- 2018
- Display Metrology
- dSiPM
- Quanta Image Sensor
- CMOS
- QIS
- Complementary Metal Oxide Semiconductor
- Digital Silicon Photo-Multiplier
- Single Photon Avalanche Diode
- SPAD
- metal object detection (MOD)
- Optoelectronic Information Science and Engineering
- Electrical Engineering and Automation
- The University of Edinburgh
- Shanghai Jiao Tong University
- STMicroelectronics Imaging Division
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Spectrophotometric Characterization of Thin Copper and Gold Films Prepared by Electron Beam Evaporation: Thickness Dependence of the Drude Damping Parameter
摘要： Copper and gold films with thicknesses between approximately 10 and 60 nm have been prepared by electron beam evaporation and characterized by spectrophotometry from the near infrared up to the near ultraviolet spectral regions. From near normal incidence transmission and reflection spectra, dispersion of optical constants have been determined by means of spectra fits utilizing a merger of the Drude model and the beta-distributed oscillator model. All spectra could be fitted in the full spectral region with a total of seven dispersion parameters. The obtained Drude damping parameters shows a clear trend to increase with decreasing film thickness. This behavior is discussed in the context of additional non-optical characterization results and turned out to be consistent with a simple mean-free path theory.
关键词： optical constants,gold,copper,ultrathin metal films,thickness dependence
更新于2025-11-21 11:01:37
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Highly sensitive and selective room-temperature NO2 gas-sensing characteristics of SnOX-based p-type thin-film transistor
摘要： The high-performance p-type metal-oxide-semiconductor (MOS)-based gas sensor is an important subject of research in the field of gas-sensing technology. In this work, we demonstrated a p-type MOS-based thin-film transistor (TFT) nitrogen dioxide (NO2) gas sensor that used tin oxide (SnOX) for both the channel and sensing layers. The crystalline status, surface morphology, and atomic-bonding configuration of the thin-film were examined using X-ray diffraction, field emission-scanning electron microscopy, and X-ray photoelectron spectroscopy. The results indicated that the deposited thin-film was mainly composed of polycrystalline SnO with a tetragonal structure. The fabricated p-type SnOX TFT showed a maximum response value of 19.4-10 ppm NO2 at room temperature (RT, 25 °C) when operated in the subthreshold region, which was significantly higher than that of 2.8–10 ppm NO2 obtained from a p-type SnOX thin-film chemiresistor at RT. In addition, the SnOX TFT gas sensor showed significantly higher sensitivity to NO2 gas than to other target gases such as NH3, H2S, CO2, and CO at RT. To the best of our knowledge, this is the first study to a p-type MOS-based field-effect transistor-type gas sensor. Our experimental results demonstrate that the p-type SnOX TFT is a promising gas sensor that can operate at RT with high sensitivity and selectivity to NO2 gas.
关键词： SnO,Thin-film transistor,NO2 gas sensing,SnOX,P-type metal oxide semiconductor
更新于2025-11-21 11:01:37
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General Synthesis of Ordered Mesoporous Rare-Earth Orthovanadate Thin Films and Their Use as Photocatalysts and Phosphors for Lighting Applications
摘要： Herein, the block copolymer templating sol-gel synthesis of a novel class of ternary oxide nanomaterials is reported. NdVO4, EuVO4, GdVO4, DyVO4, YVO4, and TmVO4 have been prepared as open mesoporous films by the dip-coating method using hydrated rare-earth nitrate salt precursors along with vanadium oxytrichloride. All materials crystallize in the tetragonal ZrSiO4-type structure with space-group I41/amd. Short-term treatment at 550 °C is found sufficient to initiate crystallization. Characterization via X-ray and electron diffraction, Raman and X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry confirms the single-phase nature and uniformity of the different orthovanadates with tailorable crystallite sizes. The integrated results from electron and atomic force microscopy, Kr-physisorption as well as in-situ and ex-situ synchrotron-based small-angle X-ray scattering reveal that the porosity persists throughout the thickness of films and the mesoscopic ordering is retained even after heating in air at 700 °C. Photobleaching experiments indicate that the sol-gel derived materials, showing an indirect band gap transition at (3.8±0.1) eV, exhibit good photocatalytic properties—the activity is highly superior to that of bulk films of the same nominal composition. Moreover, when doping GdVO4, YVO4, and solid solution GdVO4-YVO4 with trivalent rare-earth ions such as Eu3+, Dy3+, Er3+, or Tm3+ ions, the films hold promise as phosphors for lighting applications, which might pave the way toward development of (3-dimensional) intricate nanocomposites with unprecedented functionalities.
关键词： Block copolymer templating,ternary metal oxide nanostructure,photocatalyst,phosphor,sol-gel chemistry
更新于2025-11-21 10:59:37
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Cu nanoclusters in ion exchanged soda-lime glass: Study of SPR and nonlinear optical behavior for photonics
摘要： Nanomaterials with large optical nonlinearities have received considerable attention in the field of modern science and nanotechnology. In this paper, we have studied nonlinear optical and surface plasmon resonance properties and behavior of Cu nanoclusters formed in ion exchanged soda-lime glass. The soda-lime glasses were successfully doped with Cu nanoclusters in the ion-exchange process. The size of the clusters estimated from the optical absorption spectroscopy results closely matched with those obtained from the transmission electron microscopy data. The results revealed that spherical shaped Cu nanoclusters were homogeneously distributed in the glass matrix and the size of the Cu nanoclusters varied from 4 to 10 nm. The structure and chemical state were further analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The nonlinear optical behavior of the materials was analyzed using femtosecond Z-scan technique. The nonlinear refraction index (n2), nonlinear absorption coefficient (β) and the third-order nonlinear optical susceptibility (χ(3)) were estimated to be -1.72 × 10?17 m2/W, 9.96 × 10?11 m/W, and 0.56 × 10?11 esu, respectively, which shows possible application in the field of photonics.
关键词： Surface plasmon resonance,Z-scan technique,Metal forming and shaping,Structural,Nanoparticles
更新于2025-11-20 15:33:11
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One-Step Photochemical Synthesis of Transition Metal - Graphene Hybrid for Electrocatalysis
摘要： For widespread use of renewable energy such as water splitting, the development of electrocatalysts on a large-scale at a low-cost that remains safe and environmentally friendly is still a great challenge. Here, we report the use of α-aminoalkyl radicals in a one-step procedure that synthesizes transition metal nanoparticle - graphene composites via photoreduction. The organic photocatalyst 2-Methyl-1-[4-(methylthio)phenyl]-2-(morpholinyl) phenyl]-1-butanone (I-907) undergoes Norrish Type I photocleavage to generate strongly reducing α-aminoalkyl radicals, when exposed to UVA. For the first time we demonstrate its ability to reduce graphene oxide (GO) and successfully synthesize Co3O4 nanoparticles decorated on graphene (Co3O4NP-rGO). The α-aminoalkyl radicals simultaneously reduce GO and Co2+ salts which nucleates on the negatively charged GO sheets and grows to form nanoparticles. The resulting Co3O4NP-rGO showed decent catalytic activity and stability for the Oxygen Evolution Reaction (OER). Our work introduces a new and environmentally friendly synthesis procedure that can be used to produce earth abundant transition metal electrocatalysts.
关键词： photochemical synthesis,reduced graphene oxide,Graphene oxide,α-aminoalkyl radicals,water oxidation,metal nanoparticles
更新于2025-11-19 16:56:35
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Study of the Effect of Optical Illumination on Resistive Switching in ZrO2(Y) Films with Au Nanoparticles by Tunneling Atomic Force Microscopy
摘要： The effect of optical illumination on the resistive switching in ultrathin (~4 nm) ZrO2(Y) films with embedded single-layer Au nanoparticle arrays 2–3 nm in size is studied via tunneling atomic force microscopy. The ZrO2(Y) films with Au nanoparticles are grown by layerwise magnetron deposition onto glass substrates with a conductive indium-tin-oxide sublayer, followed by annealing at 450°C. An increase in hysteresis due to bipolar resistive switching in the ZrO2(Y) films is observed on the cyclic current–voltage curves of the microscope probe-to-sample contact. The effect is found to manifest itself in a dense Au nanoparticle array (~660 nm) when the contact area is photoexcited through a transparent substrate exposed to the radiation of a semiconductor laser at the plasmon-resonance wavelength. The effect is attributed to the photon-assisted field emission of electrons from Au nanoparticles to the conduction band of ZrO2(Y) in a strong electric field between the microscope probe and the indium-tin-oxide substrate under plasmon-resonance conditions.
关键词： plasmon resonance,resistive switching,yttrium-stabilized zirconium dioxide,metal nanoparticles,atomic force microscopy
更新于2025-11-19 16:56:35
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Colloidally synthesized defect-rich $$\hbox {MoSe}_{2}$$ MoSe 2 nanosheets for superior catalytic activity
摘要： Transition metal dichalcogenide (TMD) nanosheets (NSs) with defect-rich and vertically aligned edges are highly advantageous for various catalytic applications. However, colloidal synthesis of defect-rich NSs with thickness variation has been a challenging task. Here, we report a colloidal synthesis of 2H-MoSe2 NSs having a large number of defects and vertically aligned edges, where the thickness is varied by changing the amount of coordinating solvent. The Se-vacancies in these NSs have introduced defect sites which are corroborated by the presence of additional vibration modes in Raman spectra. These NSs exhibit electrocatalytic hydrogen evolution reaction performances with a low overpotential (210–225 mV) at 10 mA cm?2 current density and a small Tafel slope (54–68 mV per decade). Moreover, these MoSe2 NSs are also employed as counter electrodes (CEs) for the fabrication of dye sensitized solar cells via a cost-effective and simplified procedure. The power conversion efficiencies of 7.02 ± 0.18%, comparable with Pt CE (7.84 ± 0.10%) could be routinely achieved. These results demonstrate a novel synthetic strategy to prepare layered TMDs with superior catalytic applications.
关键词： counter electrode,Transition metal dichalcogenides,dye sensitized solar cells,MoSe2 nanosheets,hydrogen evolution reaction
更新于2025-11-19 16:56:35
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Photocatalytic and Antimicrobial Properties of Ga Doped and Ag Doped ZnO Nanorods for Water Treatment
摘要： Water contamination is a worldwide concerning problem. Emerging contaminants have made conventional water treatment processes ineffective. This makes the search for new materials with improved physical-chemical properties for water treatment an urgent necessity. Doping metal oxides nanostructures can improve the photocatalytic degradation of contaminants and the antimicrobial activity of the material. During this process, water treatment not only involves the degradation of toxic pollutants, but also the elimination of virus and bacteria. Then, it is important to study not only the effect of a dopant in a material as photocatalyst but also the effect in its antimicrobial properties. In this work ZnO nanorods, Ga doped ZnO nanorods and Ag doped ZnO nanorods are synthesized and supported in polyethylene by a fast-hydrothermal microwave heating synthesis. Their photocatalytic performance and antimicrobial properties for water treatment were evaluated. Experiments show that Ag and Ga can improve the photocatalytic and antimicrobial properties of ZnO nanorods; the relationship between doping concentrations, with both the toxicity effect of the nanorods toward bacteria and the nanorods photocatalytic performance, is shown.
关键词： doping,water,antimicrobial,nanorods,contamination,metal oxide,photocatalysis,zinc oxide
更新于2025-11-19 16:56:35
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Influence of pretreatment on surface interaction between Cu and anatase-TiO2 in the simultaneous photoremediation of nitrate and oxalic acid
摘要： Copper-promoted anatase-type TiO2 photocatalysts (2.5 wt% Cu) were prepared by wet impregnation onto TiO2 which was pre-calcined at 600°C and the other not subjected to any thermal pre-treatment. In the latter case, the material was inactive for the photo-reduction of nitrate whereas 600°C pre-calcined TiO2 yielded a material which was active for the same reaction. The surface properties of the materials were determined by BET Surface area, SEM TEM, XRD, XPS, TPR, UV-Visible diffuse reflectance, DTA, N2O pulsed chemisorption and FTIR studies. The BET and XRD and DTA showed that pre-calcination of TiO2 stabilised the support, but coalescence of particles was observed in TiO2 that was not subjected to any thermal pre-treatment as evidenced by crystallite growth. Similarly, XPS, FTIR and TPR proved the formation of Cu2O particles on the surface of pre-calcined TiO2. On the other hand, the absence of pre-calcination step resulted in interring of Cu species within the grown anatase crystallites that hindered their proper distribution over TiO2, helped in its inactiveness in the photoreduction of nitrate. However, the prepared material using pre-calcined TiO2 showed the overall nitrate and oxalic acid removal efficiency of 31 and 70% with N2 and NH4+ selectivity of 44.9 and 55.1 %, respectively. The results provide insight into the significance of activity-structure relation, inferring that the two surfaces were chemically not similar. Thus, as even supported by adsorption experiment, difference in photocatalytic behaviour amongst the prepared materials was a function of crystallinity, particle size, absence of surface defect and high energy sites.
关键词： Nitrate,photocatalyst,photoremediation,metal oxide-support interaction,oxalic acid
更新于2025-11-19 16:56:35
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An AND logic gate-based fluorescence probe for the detection of homovanillic acid, an indicator of the tumor
摘要： Homovanillic acid (HVA) is one of the major metabolites of catecholamine in human. An elevated level of HVA in urine and blood has been associated with many diseases, including catecholamine-secreting tumors. Consequently, detection of the biomarker HVA in urine is an effective strategy to detect cancer precursors and early stage cancers. In this study, a fluorescence probe is designed and fabricated by integrating lanthanide ions with metal-organic frameworks (MOFs). The fluorescence probe shows distinguished response toward HVA and exhibits ratiometric detection of HVA, rendering it an excellent candidate for sensing devices. Thus, we have designed logic gate operation integrating the probe with logical operations for the intelligent sensing of HVA. Furthermore, this type of luminesce based sensors integrated with logic gate augur for the further application in real-time early diagnosis of tumors in the future.
关键词： Rare earth,Homovanillic acid,Fluorescent probe,Logic gate,Ratiometric sensing,Metal-organic frameworks
更新于2025-11-19 16:56:35