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Few-cycle laser driven reaction nanoscopy on aerosolized silica nanoparticles
摘要： Nanoparticles offer unique properties as photocatalysts with large surface areas. Under irradiation with light, the associated near-fields can induce, enhance, and control molecular adsorbate reactions on the nanoscale. So far, however, there is no simple method available to spatially resolve the near-field induced reaction yield on the surface of nanoparticles. Here we close this gap by introducing reaction nanoscopy based on three-dimensional momentum-resolved photoionization. The technique is demonstrated for the spatially selective proton generation in few-cycle laser-induced dissociative ionization of ethanol and water on SiO2 nanoparticles, resolving a pronounced variation across the particle surface. The results are modeled and reproduced qualitatively by electrostatic and quasi-classical mean-field Mie Monte-Carlo (M3C) calculations. Reaction nanoscopy is suited for a wide range of isolated nanosystems and can provide spatially resolved ultrafast reaction dynamics on nanoparticles, clusters, and droplets.
关键词： ethanol,water,SiO2 nanoparticles,photocatalysts,nanoparticles,Mie Monte-Carlo calculations,momentum-resolved photoionization,reaction nanoscopy,near-fields
更新于2025-09-19 17:13:59
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High staility of silica-wrapped CsPbBr3 perovskite quantum dots for light emitting application
摘要： Encapsulating quantum dots (QDs) into other medium has been considered as an efficacious method to avoid the fluorescence degradation of QDs. Here, we proposed a facile method to embed CsPbBr3 perovskite QDs in silica matrix derived from (3-aminopropyl)triethoxysilane (APTES) at room temperature in open air. The QDs/SiO2 composite was extracted from the sol-gel solution by using a precipitation-encapsulation method assisted with APTES. As-prepared composite powder possess a high photoluminescence quantum yield (PLQY) of 68% and a full width at half maximum (FWHM) of ~23 nm. The QDs/SiO2 compounds show excellent stability after the five heating cycles (105 °C) and a continuous xenon irradiation (500 W, 70 °C). Besides, the products remain 94.3% and 98.6% photoluminescence (PL) intensity after 30 days of storage (25 °C) and 96 hours of ultraviolet (UV) irradiation (λ= 365 nm) respectively. The white light-emitting diode (LED) was fabricated by coating green-emitting CsPbBr3@SiO2 composite powder and commercial red phosphors on blue chip. The fabricated white LED performed excellent light characteristics with a luminous efficacy (ηL) of 58.9 lmW-1 and a correlated color temperature (CCT, Tc) of 5829 K (current = 20 mA), it also display a wide color gamut with 126.8% of National Television System Committee (NTSC) color triangle area.
关键词： white LED,stability,perovskite QDs,CsPbBr3,SiO2
更新于2025-09-19 17:13:59
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Porous Si-SiO2 UV Microcavities to Modulate the Responsivity of a Broadband Photodetector
摘要： Porous Si-SiO2 UV microcavities are used to modulate a broad responsivity photodetector (GVGR-T10GD) with a detection range from 300 to 510 nm. The UV microcavity filters modified the responsivity at short wavelengths, while in the visible range the filters only attenuated the responsivity. All microcavities had a localized mode close to 360 nm in the UV-A range, and this meant that porous Si-SiO2 filters cut off the photodetection range of the photodetector from 300 to 350 nm, where microcavities showed low transmission. In the short-wavelength range, the photons were absorbed and did not contribute to the photocurrent. Therefore, the density of recombination centers was very high, and the photodetector sensitivity with a filter was lower than the photodetector without a filter. The maximum transmission measured at the localized mode (between 356 and 364 nm) was dominant in the UV-A range and enabled the flow of high energy photons. Moreover, the filters favored light transmission with a wavelength from 390 nm to 510 nm, where photons contributed to the photocurrent. Our filters made the photodetector more selective inside the specific UV range of wavelengths. This was a novel result to the best of our knowledge.
关键词： nanotechnology,photonic nanoscience,responsivity,porous Si-SiO2,UV filters
更新于2025-09-19 17:13:59
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Ultrafast photo-annealed carbon-coated SiO2 sphere electrodes for NO2 gas sensing
摘要： There is great interest in carbon-based printed electronics as a promising technology to achieve lighter, thinner and ?exible electronic devices at low-costs. Despite the surge of enthusiasm in this area, research advances in printed electronics are not yet able to realize diverse carbon structures yet. This is due to the limitations in conventional solution-based printing methods (e.g., inkjet printing, roll-to-roll, screen printing). Processes such as polymer phase-inversion offer one possibility but a much faster and ef?cient method should be devised for reliable production. Here, we demonstrate laser printing combined with intense pulsed-light (IPL) annealing as a novel and ef?cient technique which can form inter-connected carbon spheres electrode on ?exible polymer substrate. Our observations show that the printed patterns from a laser printer consist of a solid-state polymer matrix with inorganic nanoparticles randomly embedded inside. Through ultrafast (5 ms) IPL treatment, core/shell type nanosphere arrays of carbon-coated SiO2 were successfully fabricated, which could be used as a functional platform for highly selective NO2 gas sensing.
关键词： Laser printing,Gas sensing,Intense pulsed-light,SiO2 spheres,Carbon coating
更新于2025-09-19 17:13:59
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Effect of two-step post-treatment on optical properties, microstructure, and nanosecond laser damage threshold of HfO <sub/>2</sub> /TiO <sub/>2</sub> /SiO <sub/>2</sub> multilayer high reflection films
摘要： HfO2/TiO2/SiO2 periodic multilayer high reflection films deposited by an electron beam are post-treated by two-step post-treatment and thermal annealing post-treatment, respectively. The optical properties, microstructures, surface morphologies, and laser-induced damage threshold (LIDT) of the films are studied comparatively. The results show that the two-step post-treatment enhances the high reflection films’ density and reduces the film surface roughness and the defects of the film. The test results show that the LIDT of HfO2/TiO2/SiO2 high reflection films treated by two-step post-treatment reaches 32.8 J/cm2, which is 110.26% higher than that of the untreated film. Compared with the HfO2/TiO2/SiO2 high reflection films after thermal annealing post-treatment, the LIDT increased nearly 27.6% after two-step post-treatment. Two-step post-treatment of high reflection films can effectively remove the defects on the surface of the film, reduce the oxygen vacancies inside the film, and further increase the laser damage threshold of the high reflection films.
关键词： laser-induced damage threshold,HfO2/TiO2/SiO2,two-step post-treatment,thermal annealing,multilayer high reflection films
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE) - Vancouver, BC, Canada (2019.6.12-2019.6.14)] 2019 IEEE 28th International Symposium on Industrial Electronics (ISIE) - Digital Holography for Industrial Applications
摘要： Metal–insulator–metal (MIM) capacitors with full atomic-layer-deposition Al2O3/ZrO2/SiO2/ZrO2/Al2O3 stacks were explored for the first time. As the incorporated SiO2 film thickness increased from 0 to 3 nm, the quadratic and linear voltage coefficients of capacitance (α and β) of the MIM capacitors reduced significantly from positive values to negative ones. For the stack with 3-nm SiO2 film, a capacitance density of 7.40 fF/μm2, α of ?121 ppm/V2, and β of ?116 ppm/V were achieved, together with very low leakage current densities of 3.08 × 10?8 A/cm2 at 5 V at room temperature (RT) and 5.89 × 10?8 A/cm2 at 3.3 V at 125 °C, high breakdown field of 6.05 MV/cm, and high operating voltage of 6.3 V for a 10-year lifetime at RT. Thus, this type of stacks is a very promising candidate for next generation radio frequency and analog/mixed-signal integrated circuits.
关键词： metal-insulator-metal,Al2O3/ZrO2/SiO2/ZrO2/Al2O3,Atomic-layer-deposition,voltage coefficients of capacitance
更新于2025-09-19 17:13:59
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Femtomolar Detection of Spermidine using Au Decorated SiO <sub/>2</sub> Nanohybrid on Plasmon-Coupled Extended Cavity Nanointerface: A Smartphone based Fluorescence Dequenching approach
摘要： Coupling of photons with molecular emitters in different nanocavities have resulted in transformative plasmonic applications. The rapidly expanding field of surface plasmon-coupled emission (SPCE) has synergistically employed subwavelength optical properties of localized surface plasmon resonance (LSPR) supported by nanoparticles (NPs) and propagating surface plasmon polaritons assisted by metal thin films for diagnostic and point-of-care analysis. Gold nanoparticles (AuNPs) significantly quench the molecular emission from fluorescent molecules (at close distances < 5 nm). More often, complex strategies are employed for providing a spacer layer around the AuNPs to avoid direct contact with fluorescent molecules, thereby preventing quenching. In this study we demonstrate a rapid and facile strategy with the use of Au-decorated SiO2 NPs (AuSil), a metal (Au)-dielectric (SiO2) hybrid material for dequenching the otherwise quenched fluorescence emission from radiating dipoles and to realize 88-fold enhancement using the SPCE platform. Different loading of AuNPs were studied to tailor fluorescence emission enhancements in spacer, cavity and extended (ext.) cavity nanointerfaces. We also present femtomolar detection of spermidine using this nanohybrid in a highly desirable ext. cavity interface. This interface serves as an efficient coupling configuration with dual benefits of spacer and cavity architectures that has been widely explored hitherto. The multifold hot-spots rendered by the AuSil nanohybrids assist in augmented electromagnetic (EM)-field intensity that can be captured using a smartphone based SPCE platform presenting excellent reliability and reproducibility in spermidine detection.
关键词： fluorescence enhancements,extended cavity nanointerface,Au-decorated SiO2 NPs (AuSil),dequenching,surface plasmon-coupled emission
更新于2025-09-19 17:13:59
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Strain Engineering Coupled with Optical Regulation towards High-sensitivity In2S3 Photodetector
摘要： Non-layered 2D materials possess intriguing properties, widening the scope of 2D libraries and promising considerable potential for applications in next-generation optoelectronics. However, due to the surface dangling bonds and weak light adsorption arising from atomically thin thickness, their photosensitivity is still limited. Herein, we achieve an ultrasensitive 2D In2S3 photodetector by adopting strain engineering coupled with optical regulation. A SiO2 nanograting array was introduced to construct strained morphology of 2D In2S3. This morphology induces charge localization and renders back-to-back built-in electric field array, which efficiently suppresses the dark current and separates the photo-excited carriers. Simultaneously, the SiO2 nanograting array realizes light management and improves the light harvesting. As a result, the device presents an ultralow dark current of 3.2 pA with a high signal-to-noise ratio up to 1.7 × 106. Especially, a prominent photoresponsivity of 1810 A/W, an excellent detectivity of 2.09 × 1015 Jones and a fast response speed of 0.41 ms are achieved. This work depicts an effective scheme to associate photonic/electronic properties manipulation for optoelectronic applications.
关键词： strain engineering,SiO2 nanograting,In2S3,optical regulation,photodetector,2D materials
更新于2025-09-19 17:13:59
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Sub-nm-Scale Depth Profiling of Nitrogen in NO- and N<sub>2</sub>-Annealed SiO<sub>2</sub>/4H-SiC(0001) Structures
摘要： We demonstrated an x-ray photoelectron spectroscopy (XPS)-based technique to reveal the detailed nitrogen profile in nitrided SiO2/4H-SiC structures with sub-nanometer-scale-resolution. In this work, nitric oxide (NO)- and pure nitrogen (N2)-annealed SiO2/4H-SiC(0001) structures were characterized. The measured results of NO-annealed samples with various annealing duration indicate that preferential nitridation just at the SiO2/SiC interfaces (~0.3 nm) proceeds in the initial stage of NO annealing and a longer duration leads to the distribution of nitrogen in the bulk SiO2 within few nanometers of the interface. The high-temperature N2 annealing was found to induce not only SiO2/SiC interface nitridation similarly to NO annealing but also SiO2 surface nitridation.
关键词： NO-annealing,N2-annealing,SiO2/SiC interface,XPS,nitrogen profile
更新于2025-09-16 10:30:52
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Low-voltage self-assembled indium tin oxide thin-film transistors gated by microporous SiO <sub/>2</sub> treated by H <sub/>3</sub> PO <sub/>4</sub>
摘要： Ultralow-voltage (0.8 V) thin-film transistors (TFTs) using self-assembled indium-tin-oxide (ITO) as the semiconducting layer and microporous SiO2 immersed in 5% H3PO4 for 30 minutes with huge electric-double-layer (EDL) capacitance as the gate dielectric are fabricated at room temperature. The huge EDL specific capacitance is 8.2 mF cm-2 at 20 Hz, and about 0.7 mF cm-2 even at 1 MHz. Both enhancement mode (Vth = 0.15 V) and depletion mode (Vth = -0.26 V) operation are realized by controlling the thickness of the self-assembled ITO semiconducting layer. Electrical characteristics with the equivalent field-effect mobility of 65.4 cm2 V-1 s-1, current on/off ratio of 2 × 106, and subthreshold swing of 80 mV per decade are demonstrated, which are promising for fast-switching and low-power electronics on temperature-sensitive substrates.
关键词： self-assembled,thin-film transistors,H3PO4,microporous SiO2,indium tin oxide,Low-voltage
更新于2025-09-16 10:30:52