Silver nanoparticle (NP) paste was fabricated and used to bond copper wire to copper foil at low temperatures down to 160°C. The silver NP paste was developed by increasing the concentration of 50 nm silver NP sol from 0.001 vol.% to 0.1 vol.% by centrifugation. The 0.001 vol.% silver NP sol was fabricated in water by reducing silver nitrate (AgNO 3 ) using sodium citrate dihydrate (Na 3 C 6 H 5 O 7 AE2H 2 O). The bond was formed by solid-state sintering among the individual silver NPs and solid-state bonding of these silver NPs onto both copper wire and foil. Metallurgical bonds between silver NPs and copper were confirmed by transmission electron microscopy (TEM). The silver NPs were coated with an organic shell to prevent sintering at room temperature (RT). It was found that the organic shell decomposed at 160°C, the lowest temperature at which a bond could be formed. Shear tests showed that the joint strength increased as the bonding temperature increased, due to enhanced sintering of silver NPs at higher temperatures. Unlike low-temperature soldering techniques, bonds formed by our method have been proved to withstand temperatures above the bonding temperature.

A molecular dynamics simulation based on the embedded-atom method was conducted at different sizes of single-crystal Ag nanoparticles (NPs) with diameters of 4 to 20 nm to find complete melting and surface premelting points. Unlike the previous theoretical models, our model can predict both complete melting and surface premelting points for a wider size range of NPs. Programmed heating at an equal rate was applied to all sizes of NPs. Melting kinetics showed three different trends that are, respectively, associated with NPs in the size ranges of 4 to 7 nm, 8 to 10 nm, and 12 to 20 nm. NPs in the first range melted at a single temperature without passing through a surface premelting stage. Melting of the second range started by forming a quasi-liquid layer that expanded to the core, followed by the formation of a liquid layer of 1.8 nm thickness that also subsequently expanded to the core with increasing temperature and completed the melting process. For particles in the third range, the 1.8 nm liquid layer was formed once the thickness of the quasi-liquid layer reached 5 nm. The liquid layer expanded to the core and formed thicker stable liquid layers as the temperature increased toward the complete melting point. The ratio of the quasi-liquid layer thickness to the NP radius showed a linear relationship with temperature.

A quantum-tunneling metal-insulator-metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP-CVD) for the first time. This scalable method is used to produce MIM diodes with high-quality, pinhole-free Al 2 O 3 films more rapidly than by conventional vacuum-based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum-enabled devices. In fact, the MIM diodes fabricated by AP-CVD show a lower effective barrier height (2.20 eV) at the electrodeinsulator interface than those fabricated by conventional plasma-enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero-bias resistance, and better asymmetry of 107.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201805533. dielectric layer sandwiched between two metal contacts. MIM diodes are capable of rectification in the high frequency range due to a femtosecond quantum-tunneling electron transport mechanism through the insulator, making them attractive for applications in solar rectennas, [1] infrared detectors, [2,3] and wireless power transmission. [4] However, the insulator layer in the MIM stack, which plays a crucial role in determining the diode performance, [5] is typically deposited using vacuum-based methods, such as sputtering, [6] anodic oxidation of sputtered films, [7] electron beam deposition, [8] and especially atomic layer deposition (ALD), [9] which is commonly used due to its ability to deposit nanoscale films with high accuracy and uniformity. High-throughput fabrication of MIM diodes is limited by slow deposition rates and the need for a vacuum environment. Scalable techniques are therefore needed for depositing nanoscale films for the next generation of integrated quantum devices. Some deposition processes have been introduced to fabricate thin films at atmospheric pressure for nanoelectronic devices that utilize quantum phenomena. Thermal and anodic oxidation, for example, have been used to grow thin CrO x and Nb 2 O 5 films on Cr and Nb layers for MIM diodes [7,10] ; atmospheric pressure metal organic vapor phase epitaxial growth (AP-MOVPE), or atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD), has been used to fabricate InGaAsP multiquantum-well structures for optical devices [11] ; the Langmuir Blodgett technique was used to deposit a ZnO film for a MIM diode [12] ; and a chemical vapor deposition (CVD) furnace operated at atmospheric pressure has been used to deposit a TiO 2 film in a tunneling transistor. [13] The need for high temperatures, specific metal films for oxidation, and complex compound precursors in these techniques, as well as challenges in reproducibility, highlight the need for new methods to reliably deposit enabling films for cost-effective quantum devices. Recently, atmospheric pressure spatial atomic layer deposition (AP-SALD) systems have been utilized to grow uniform films for different applications including solar cells...

We studied the exposure behavior of low molecular weight polystyrene as a negative tone electron beam lithography (EBL) resist, with the goal of finding the ultimate achievable resolution. It demonstrated fairly well-defined patterning of a 20-nm period line array and a 15-nm period dot array, which are the densest patterns ever achieved using organic EBL resists. Such dense patterns can be achieved both at 20 and 5 keV beam energies using different developers. In addition to its ultra-high resolution capability, polystyrene is a simple and low-cost resist with easy process control and practically unlimited shelf life. It is also considerably more resistant to dry etching than PMMA. With a low sensitivity, it would find applications where negative resist is desired and throughput is not a major concern.

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biomedicine, [2,3] tribology, [4] photonics, [5] and electrocatalysis, [6] among others. Significant progress has been made recently in fabricating and functionalizing 2D nanosheets of transition metal dichalcogenides. [7] This progress has focused on the functionalization of mono-or few-layer nanosheets with lateral dimensions greater than 100 nm by combining chemical exfoliation, [8][9][10][11][12] micromechanical exfoliation, [13] or liquid exfoliation [14] with the reaction of functionalities. The formation and functionalization of smaller 2D nanoparticles or quantum dots, on the other hand, is still in its infancy.In what has been cited as the first direct evidence of covalent functionalization of a nanoscale transition metal dichalcogenide, Tuxen et al. produced MoS 2 monolayer nanoclusters in ultrahigh vacuum on a gold substrate and attached dibenzothiophene molecules to the clusters via controlled vapor exposure. [15,16] Beyond substrate-supported nanoclusters, the functionalization of nongraphene 2D nanoparticles suspended in solution was reported last year. Atkin et al. combined ultrasonication of WS 2 with microwave treatment in a citric acid-containing solution to produce monolayer WS 2 nanosheets ≈20-80 nm in diameter decorated with 2-5 nm carbon dots. [6] Jung et al. impinged BN flakes with super-heated nanoparticles then exposed them to water vapor to produce edge-hydroxylated BN quantum dots with 8 nm lateral size. [2] These techniques for fabricating and functionalizing 2D nanosheets and smaller nanoparticles are relatively slow (in some cases requiring several days), often require dangerous chemicals and elevated temperatures, and their demonstration has been material specific. In the case of functionalized 2D nanoparticles other than graphene, such as functionalized MoS 2 , WS 2 , and BN quantum dots, potentially exciting multifunctional optical properties have not been realized. The ability to produce a variety of hybrid 2D nanoparticles that possess the optical properties of both the host 2D material and functional groups would be extremely valuable for many of the aforementioned applications.We introduce a rapid femtosecond laser technique that simultaneously reduces the dimensions of flakes of 2D materials to a few nanometers and dissociates solvent molecules to bond with the edges of the freshly cleaved 2D sheets, in order to produce functionalized nanoparticles of 2D materials. Etha nol, a common and inexpensive solvent, is used to facilitate functionalization A general, rapid technique is introduced to simultaneously fabricate and functionalize nanoparticles of 2D materials. A femtosecond laser is used to irradiate flakes of 2D materials in an ethanol-containing solvent. The highly energetic laser pulses exfoliate and cleave the flakes into nanosheets with diameters of ≈3 nm and simultaneously dissociate the solvent molecules. The dissociated carbon and oxygen atoms bond with the freshly cleaved 2D nanoparticles to satisfy edge sites, resulting in the formation of hybrid 2D nanoparticles...

Micro and nano-joining has been identified as a key enabling technology in the construction of micromechanical and microelectronic devices. The current article reviews recent progress in micro and nano-joining. In particular, laser micro-welding (LMW) of crossed 316 LVM stainless steel (SS) wire was compared to conventional resistance microwelding (RMW) and was successfully employed in welding a Pt-Ir /SS dissimilar combination. Welding of Au nanoparticles was realized using femtosecond laser irradiation and its application in the surface enhanced Raman spectroscopy was investigated. Brazing between carbon nanotube (CNT) bundles and Ni electrodes was attained in vacuum, resulting in the development of a novel CNT filament of incandescent lamps.

Localized Surface Plasmon Resonance (LSPR) sensors have potential applications in essential and important areas such as bio-sensor technology, especially in medical applications and gas sensors in environmental monitoring applications. Figure of Merit (FOM) and Sensitivity (S) measurements are two ways to assess the performance of an LSPR sensor. However, LSPR sensors suffer low FOM compared to the conventional Surface Plasmon Resonance (SPR) sensor due to high losses resulting from radiative damping of LSPs waves. Different methodologies have been utilized to enhance the performance of LSPR sensors, including various geometrical and material parameters, plasmonic wave coupling from different structures, and integration of noble metals with graphene, which is the focus of this report. Recent studies of metal-graphene hybrid plasmonic systems have shown its capability of promoting the performance of the LSPR sensor to a level that enhances its chance for commercialization. In this review, fundamental physics, the operation principle, and performance assessment of the LSPR sensor are presented followed by a discussion of plasmonic materials and a summary of methods used to optimize the sensor’s performance. A focused review on metal-graphene hybrid nanostructure and a discussion of its role in promoting the performance of the LSPR sensor follow.