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Thermal and mechanical properties play a key role in optimizing the performance of nanoelectronic devices. In this study, the lattice thermal conductivity (κL) and elastic constants of Si nanosheets at different sheet thicknesses were determined using recently developed machine learning interatomic potentials (MLIPs). A Si nanosheet with a minimum thickness of 10 atomic layers was used for model training to predict the properties of sheets with greater thicknesses. The training dataset was efficiently constructed using stochastic sampling of the potential energy surface (PES). Density functional theory (DFT) calculations were used to extract
the MLIP, which served as the basis for further analysis. The Moment Tensor Potential (MTP) method was used to obtain the MLIP in this study. The results showed that, at sub-6 nm sheet thickness, the thermal conductivity dropped to ∼ 7 % of its bulk value, whereas some stiffness tensor components dropped to ∼ 3 % of the bulk values. These findings contribute to the understanding of heat transport and mechanical behavior of ultrathin Si nanosheets, which is crucial for designing and optimizing nanoelectronic devices. The technological implications of the extracted parameters on nanosheet field-effect transistor (NS-FET) performance at advanced technology nodes were evaluated using TCAD device simulations., (© 2024 IOP Publishing Ltd. All rights, including for text and data mining, AI training, and similar technologies, are reserved.)

A detailed understanding of the connections of fabrication and processing to structural and thermal properties of low-dimensional nanostructures is essential to design materials and devices for phononics, nanoscale thermal management, and thermoelectric applications. Silicon provides an ideal platform to study the relations between structure and heat transport since its thermal conductivity can be tuned over 2 orders of magnitude by nanostructuring. Combining realistic atomistic modeling and experiments, we unravel the origin of the thermal conductivity reduction in ultrathin suspended silicon membranes, down to a thickness of 4 nm. Heat transport is mostly controlled by surface scattering: rough layers of native oxide at surfaces limit the mean free path of thermal phonons below 100 nm. Removing the oxide layers by chemical processing allows us to tune the thermal conductivity over 1 order of magnitude. Our results guide materials design for future phononic applications, setting the length scale at which nanostructuring affects thermal phonons most effectively.

Hydrogen has been recognized as a future energy carrier that may allow a gradual transformation from a fossil fuel-based economy to a hydrogen economy. One of main obstacles to implement hydrogen economy is efficient storage of hydrogen. Up to present, none of proposed storage methods completely satisfy all department of energy (DOE) target criteria with gravimetric capacity ~5.5 wt% and loss rate 0.1 (g/h)/kg for hydrogen storage yet. Here we demonstrate high density of hydrogen nano-bubble (HNB) up to ~3.4±0.18 wt% can be efficiently generated and stored via an electron radiolysis assisted abstraction reaction (RAAR) in an encapsulated quasi-2D water reservoir containing organic molecules. The RAAR is a reaction between radiolytic water species and the surface groups of organic molecules. In our system, the long term stability of HNB comes from supersaturation of hydrogen molecules controllable by the electron dose rate and concentration of the organic molecule. The best gravimetric capacity and loss rate in our experiment are ~3.4±0.18 wt% and 0.18(g/h)/kg, respectively, in 25 °C and at 1 bar which fall closely to the DOE targets. A TEM equipped with a continuous flow holder with a quasi-2D water reservoir is utilized for in-situ generation and storage of HNB. The regeneration time for HNB formation is in the order of a few ten seconds. This process can be linked with the microbial electrolysis cell technology that converts hydrogen from wastewater containing abundant organics. [ABSTRACT FROM AUTHOR]

Recently hybrid structure of hydrogen nanobubble (HNB) and gold nanoparticles (GNP) have attracted a great deal of interest in many potential applications including ultrasound contrast agent, cancer therapy and drug delivery. For the first time, here we reported interaction of high energy electron beam with sodium citrate catalyzes a highly stable hybrid super structure (HNB ∈ Au) where sub-nanometer sized GNPs are decorated on the HNB surface. The formation mechanism of HNB ∈ Au has been in-depth studied in this work. This electron radiation technique is the easiest method for the large-scale production of environmentally benign sub-nanometer sized GNP and HNB at room temperature. We have successfully demonstrated the HNB can serve as a substrate or a template for attracting Au nano-clusters onto its surface by in-situ transmission electron microscopy in liquid environment. The kinetics of multiple coalescence process of merging ultra-small GNP and HNB has been analyzed with Mehl-Avrami-Kolmogorov (JMAK) scheme. It suggests that the growth modes for HNB and GNP in the formation process of HNB ∈ Au are 2D and 3D, respectively. Here we have also calculated the momentum transferred to the GNP from the incident electrons and surrounding liquid molecules. It indicates that the incident electrons can trigger the GNP sliding on HNB surface at relatively high dose rate. For Table of Contents Only. [Display omitted] • Hybrid Nano-Structured Au Particles/Nanobubble formation with the interaction of high energy electron beam. • The formation mechanism of HNB ∈ Au has been in-depth studied in this work. • HNB can serve as a substrate/template for attracting Au nanoclusters onto its surface observed by in-situ liquid cell TEM. • This new hybrid superstructure (HNB ∈ Au) can bring a profound impact on the physical and chemical science community. [ABSTRACT FROM AUTHOR]