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.

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 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...

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