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Visible light from modulated electron beam moving between twin circular silver nanowires forming plasmonic photonic molecule
摘要： The visible-range diffraction radiation of harmonically modulated electron beam, which moves between twin circular silver nanowires is considered. The electromagnetic field of such a two-dimensional beam is a surface wave propagating along its trajectory with the phase velocity equal to the beam velocity. This wave induces currents on the nanowires and hence radiation occurs even if the beam does not touch the wires. If the wires are tuned to a resonance, the radiated power displays a peak proportional to the resonant mode Q-factor. Sub-wavelength in radius silver nanowires are famous as nanoresonators due to the localized surface-plasmon modes. In our analysis, we use the field expansions in the azimuthal Fourier series and the addition theorems for the cylindrical functions. This enables us to reduce the wave scattering problem to a Fredholm second kind infinite-matrix equation that guarantees convergence of numerical solutions. Truncating this matrix, we compute the near and far field patterns of the wires as optically coupled plasmonic resonators and analyse dependence of the far-field spectral characteristics on the wavelength and electron beam parameters.
关键词： absorption cross-section,optical diffraction radiation,total scattering cross-section,plasmon resonance,surface wave,silver nanowires
更新于2025-09-12 10:27:22
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Light intensity and spectral dependence characteristics of silicon nanowire/PEDOT:PSS heterojunctions solar cells
摘要： Recently, research on Si/conducting organic polymer heterojunction solar cells has gained prominence owing to their low fabrication cost and potential for reasonably good efficiency. Poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) coated over n-type Si forms such heterojunction which has theoretical capabilities comparable to the conventional p-n Si junction. However these devices still need fabrication parameters optimization in order to compete with conventional p-n junction silicon solar cells. Here, we report the photoresponse of Ag/PEDOT:PSS/n-SiNW/Al solar cell at different light intensities and different wavelengths. The device is fabricated by spin coating the PEDOT:PSS over n-Si NW based Si substrates. It is further noted that the short circuit current is significantly lower in J-V response than that derived from external quantum efficiency measurements. It is observed that the photocurrent density and fill factor deteriorates significantly at higher intensities. This is suggestive of some space charge build up at Si-PEDOT:PSS interface at higher intensities because of difference in hole mobility in Si and PEDOT:PSS. This could also be strongly attributed to structural changes in the PEDOT:PSS layer which might change the charge carrier dynamics and hence the electrical response of the layer. The response of cell with varying intensity can help to optimize the illumination condition for the cell. The wavelength response of the cell can help us better understand the solar cell working and can help in optimizing the fabrication parameters. This opens up new area of intensive research required in order to optimize polymer layer properties and improving the performance of PEDOT:PSS/SiNW-based solar cell.
关键词： PEDOT:PSS,Hetero-junction solar cells,Silicon nanowires,Light trapping
更新于2025-09-12 10:27:22
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Recent advances in flexible photodetectors based on 1D nanostructures
摘要： Semiconductor nanowires have demonstrated excellent electronic and optoelectronic properties. When integrated into photodetectors, excellent device performance can be easily attained. Apart from the exceptional performance, these nanowires can also enable robust and mechanically flexible photodetectors for various advanced utilizations that the rigid counterparts cannot perform. These unique applications include personal healthcare, next-generation robotics and many others. In this review, we would first discuss the nanowire fabrication techniques as well as the assembly methods of constructing large-scale nanowire arrays. Then, the recent development of flexible photodetectors based on these different nanowire material systems is evaluated in detail. At the same time, we also introduce some recent advancement that allows individual photodetectors to integrate into a more complex system for advanced deployment. Finally, a short conclusion and outlook of challenges faced in the future of the community is presented.
关键词： photodetectors,flexible,nanowires
更新于2025-09-11 14:15:04
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Catalyst‐Free Vapor–Solid Deposition Growth of β‐Ga <sub/>2</sub> O <sub/>3</sub> Nanowires for DUV Photodetector and Image Sensor Application
摘要： Photodetection in the solar-blind deep-ultraviolet (DUV) regime (200–280 nm) has received significant attention for its many critical applications in military and civil areas. In this study, a vapor–solid synthesis technique for catalyst-free growth of single-crystalline β-Ga2O3 nanowires is developed. A photodetector made of the nanowires is highly sensitive to 265 nm DUV illumination with excellent photoresponse performance. The performance parameters including Ilight/Idark ratio, responsivity, specific detectivity and response speed can attain ≈103, ≈233 A W?1, ≈8.16 × 1012 Jones, and 0.48/0.04 s, respectively. Additionally, the detector has an abrupt response cutoff wavelength at ≈290 nm with a reasonable DUV/visible (250–405 nm) rejection ratio exceeding 102. It is also found that the device can operate properly at a large applied bias of 200 V with the responsivity being enhanced to as high as ≈1680 A W?1. Moreover, such a nanowires-based photodetector can function as a DUV light image sensor with a reasonable spatial resolution. Holding the above advantages, the present DUV photodetector based on catalyst-free grown β-Ga2O3 nanowires possesses huge possibility for application in future DUV optoelectronics.
关键词： DUV photodetectors,catalyst-free growth,nanowires,image sensors,β-Ga2O3
更新于2025-09-11 14:15:04
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Well‐Controlled Decomposition of Copper Complex Inks Enabled by Metal Nanowire Networks for Highly Compact, Conductive, and Flexible Copper Films
摘要： Highly compact and conductive Cu films are successfully fabricated by introducing mechanically robust and highly conductive metal nanowires (NWs) as fillers and optimizing amine-based ligands in Cu complex inks. The metal NWs (AgNWs and CuNWs) dispersed in the complex inks provide networks of nucleation sites for the in situ formed Cu particles and thereby control the decomposition of Cu complex inks at low temperatures to realize Cu films with high uniformity and integrality. The high affinity between metal NWs and the in situ formed Cu element enables the growth of Cu particles along the metal NWs to create a compact structure. Besides, the amine-based ligands such as 2-amino-2-methyl-1-propanol (AMP), 2-ethylhexylamine (Ethy), and hexylamine (Hexy) are varied to adjust the size of Cu particles and further improve the microstructure and conductivity of the sintered Cu films. The Cu-Ethy complex/metal NW inks sintered at 140 °C exhibit the lowest resistivity of 14.9 μ? cm, which is about one-third that fabricated from the pure Cu-AMP complex inks. The flexible light-emitting diode circuits and V-shaped dipole antennas prepared from the Cu complex/metal NW inks have excellent performance due to their outstanding conductivity and flexibility, showing great potential in the fabrication of cost-effective, flexible printed electronic devices.
关键词： antennas,controllable decomposition,metal nanowires,Cu complex inks,amine-based ligands
更新于2025-09-11 14:15:04
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Axial Heterostructures with Phase-Controlled Metastable Segments via Post-Growth Reactions of Ge Nanowires
摘要： Metastable crystal phases promise new functionalities by providing access to materials properties beyond those of thermodynamically stable crystalline solids. While realizing metastable phases in the bulk requires non-equilibrium processes such as rapid quenching or high pressures, size effects at the nanometer scale can promote their formation and stabilization during mild processing. Here we demonstrate the controlled formation of axial heterostructures of alternating stable semiconductor (Ge) and metastable metallic (AuGe) segments via post-growth processing, by decorating Ge nanowires with Au, encapsulating them in graphitic carbon shells, annealing at moderate temperatures to induce alloying of Au and Ge in the melt, followed by slow cooling and crystallization. The process is extended to form heterostructures of binary AgGe and ternary AuAgGe alloy segments in Ge nanowires. The metallic alloys adopt different metastable crystal phases that are selected via the nanowire diameter. This phase selection, explained by a size-dependent solubility of Ge in liquid AuGe (and AgGe) and distinct structural motifs in Ge-rich AuGe melts, allows establishing a previously unknown metastable γ-AgGe metastable in thin axially segmented Ge-AgGe nanowires. The findings demonstrate an avenue for synthesizing axial heterostructures of stable and metastable solid phases in nanowires.
关键词： heterostructures,size effects,AuGe,AgGe,metastable phases,nanowires,phase selection,AuAgGe
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || FIB patterning for position-controlled nanowire growth
摘要： Semiconductor nanowire (NW) based heterostructures are a promising material system for next generation optoelectronic devices, such as flexible solar cells and light emitting diodes [1]. Their reduced contact area and surface strain relaxation allow for epitaxial growth on lattice-mismatched substrates, a key advantage for integration of different III-V semiconductors with existing silicon-based technology. Position-controlled NWs can be grown in ordered arrays on Si to improve uniformity and device integration. This is commonly performed by using a SiO2 thin film as a mask. Patterning of circular holes in the mask (Fig. 1(a)) allows for site-specific NW growth in predefined patterns and positions. To date, this is performed using lithography techniques such as electron beam lithography or nanoimprint lithography [2]. Important processing parameters include oxide thickness, hole diameter and pattern pitch, requiring several steps to be optimized in order to achieve a high yield of uniform NWs [3]. Additionally, the catalytic particle is rarely centered in the hole, leading to undesirable asymmetry in the NW cross-sections [4]. In this work, the parameter space for direct patterning of NW growth substrates by focused ion beam (FIB) is explored (Fig. 1). Self-catalyzed GaAsSb NWs were grown using molecular beam epitaxy (MBE) on a FIB patterned Si(111) substrate with 40 nm thermal oxide, where hole size, dose and Ga-beam overlap were systematically varied (Fig. 1(a-c)). It is expected that a higher degree of flexibility and control can be attained using FIB compared to the conventionally used resist-based patterning techniques. In addition, patterning by FIB leads to Ga implantation in both Si and SiO2, which could positively affect the self-catalyzed NW growth and the properties of the NW-substrate system in a unique way. After MBE growth, three distinct growth regimes can be recognized, present in all arrays (Fig. 1(d-e)): The smallest (10 nm pattern) diameter row features a high yield (≤ 80%) of straight NWs. As the hole diameter increases there is initially a transition to more parasitic crystal growth and finally multiple (2-5) NWs grow within each hole. As the dose increases between arrays in each column, the patterned diameter for these transitions decreases proportionally. The results demonstrate that using FIB the parameter space can be mapped out efficiently within a single growth session and that growth can be tuned between aligned single NWs, 2D parasitic crystals and multiple NWs per hole. Transmission electron microscopy and electrical testing of single NWs directly on the growth substrate [5] will be used to refine the structural analysis and study the electrical properties of these NWs. It is expected that in addition to the flexibility of FIB patterning, III-V NWs grown on FIB-patterned Si will exhibit novel properties due to the implantation of Ga and the altered NW-substrate interface.
关键词： self-catalyzed,nanowires,focused ion beam,nanostructuring,GaAsSb
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Structural transformations revealed by in-situ HRTEM observations
摘要： With the recent advance of In-Situ Transmission Electron Microscopy (In-Situ TEM), it has become a very essential technique to understand the structure-property relationships of materials. Here, we demonstrate that the formation mechanism of 1D-Si nanowires is initiated by the atom intrusion into the Si lattice at the interfaces, and the formation process is advanced by the atom intrusion into the Si lattice at the interfaces. The formation mechanism of 1D-Si nanowires is also discussed by the thermodynamic analysis. It is found that the 1D-Si nanowires are formed at the triple junction at the interfaces, and the formation process is advanced by the atom intrusion into the Si lattice at the interfaces. The formation mechanism of 1D-Si nanowires is also discussed by the thermodynamic analysis.
关键词： formation mechanism,atom intrusion,In-Situ TEM,thermodynamic analysis,1D-Si nanowires
更新于2025-09-11 14:15:04
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Dynamics Contributions to the Growth Mechanism of Ga2O3 Thin Film and NWs Enabled by Ag Catalyst
摘要： In the last few years, interest in the use of gallium oxide (Ga2O3) as a semiconductor for high power/high temperature devices and UV nano-sensors has grown. Ga2O3 has an enormous band gap of 4.8 eV, which makes it well suited for applications in harsh environments. In this work, we explored the effect of Ag thin film as a catalyst to grow gallium oxide. The growth of gallium oxide thin film and nanowires can be achieved by heating and oxidizing pure gallium at high temperatures (~1000 °C) in the presence of trace amounts of oxygen. We present the results of structural, morphological, and elemental characterization of the β-Ga2O3 thin film and nanowires. In addition, we explore and compare the sensing properties of the β-Ga2O3 thin film and nanowires for UV detection. The proposed process can be optimized to a high scale production Ga2O3 nanocrystalline thin film and nanowires. By using Ag thin film as a catalyst, we can control the growth parameters to obtain either nanocrystalline thin film or nanowires.
关键词： Ga2O3,thermal oxidation,nanowires,thin film,silver catalyst,quartz
更新于2025-09-11 14:15:04
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3D Multi-Branched SnO2 Semiconductor Nanostructures as Optical Waveguides
摘要： Nanostructures with complex geometry have gathered interest recently due to some unusual and exotic properties associated with both their shape and material. 3D multi-branched SnO2 one-dimensional nanostructrures, characterized by a “node”—i.e., the location where two or more branches originate, are the ideal platform to distribute signals of di?erent natures. In this work, we study how this particular geometrical con?guration a?ects light propagation when a light source (i.e., laser) is focused onto it. Combining scanning electron microscopy (SEM) and optical analysis along with Raman and Rayleigh scattering upon illumination, we were able to understand, in more detail, the mechanism behind the light-coupling occurring at the node. Our experimental ?ndings show that multi-branched semiconductor 1D structures have great potential as optically active nanostructures with waveguiding properties, thus paving the way for their application as novel building blocks for optical communication networks.
关键词： SnO2,waveguiding e?ect in nanostructures,3D multi-branched nanostructures,nanowires,light scattering,tin oxide nanostructure,nano-optics
更新于2025-09-11 14:15:04