GAA (Gate All Around) FETs have been developed for 2 nm-generation logic devices. This paper discusses key etching challenges and technologies for the device, Si/SiGe nanosheet etching with H₂ gas chemistry using a Microwave ECR etching tool, reduced WFM (Work Function Metal) erosion and enhanced nano-space etching capability in WFM patterning through DC pulse technology, and HK (High-K)/WFM recess etching employing an ALE (Atomic-Layer Etching)-like approach with boron deposition control. Additionally, this paper demonstrates conformal ALE of Si₃N₄ in nanoscale spaces using a Dry Chemical Removal (DCR) tool equipped with an IR lamp.

We investigated two types of surface plasmons―localized surface plasmon resonance (LSPR) and surface plasmon polaritons (SPPs)―and their interplay using size-selected Ag, Au, and Cu nanoclusters (NCs) and ultrafast spectroscopy. Atomically precise NCs were prepared by magnetron sputtering with mass selection and deposited on C₆₀-modified substrates. Two-photon photoemission spectroscopy (2PPE) revealed threshold sizes for plasmon emergence (≥9 atoms for Ag, ≥21 for Au) and clarified the influence of d-band structures. Dual-color 2P-PEEM visualized SPP propagation at metal–organic interfaces, showing that LSPR enhancement and molecular modifications can tune SPP characteristics, even at buried interfaces using NC sensitizers. These results provide key insights into size- and structure-dependent plasmonic behavior and inform the design of advanced photoelectronic and nanophotonic devices.

Photocatalysis enables redox reactions to proceed non-thermally under ambient conditions, offering a low-energy alternative to conventional thermocatalytic processes. Traditionally, it has been assumed that oxidation occurs exclusively at the semiconductor surface via photogenerated holes, while reduction takes place on metal cocatalysts that capture photogenerated electrons. However, the absence of microscopic insights into the detailed reaction mechanism has hindered rational design of catalysts. To address this, we employed kinetic analysis and operando infrared spectroscopy to directly monitor reactive species under reaction conditions. Our investigations reveal that metal cocatalysts also play a crucial role in oxidation by interacting with photogenerated holes, contrary to traditional understanding. Moreover, the reactive electrons are not located within the metal cocatalysts but are shallowly trapped in in-gap states of the semiconductor surface at their periphery. These findings redefine the concept of catalytic active sites and provide a basis for designing more efficient photocatalytic systems.

Electron beam powder bed fusion (EB-PBF), one of additive manufacturing, utilizes an electron beam as a heat source and has advantages such as a scanning strategy with high-speed operation, high thermal conversion efficiency, and residual stress relief by preheating process. On the other hand, it has inferior surface roughness, a powder scattering phenomenon known as smoke, and the need to remove pre-sintered powder. In addition to these general features of EB-PBF, other features of EB-PBF have been developed in recent years : high-quality electron beam, and defect detection through backscattered electron (BSE) image monitoring. EB-PBF is suitable for Ti-6Al-4V alloys, pure copper, Ni718 alloys and pure tungsten, and meets AMS standard certification, crack-free and microstructure control.

Hydrogen readily permeates various materials and modulates their physical properties. Identification of the hydrogen lattice location in crystals is key to understanding and controlling the hydrogen-induced phenomena. Combining nuclear reaction analysis (NRA) with the ion channeling technique, we experimentally determined the locations of H and D in epitaxial nanofilms of titanium hydrides. We found that 11 at.% of H are located at the octahedral site with the remaining H atoms in the tetrahedral site. Density functional theory calculations revealed that the partial octahedral site occupation is attributed to the Jahn-Teller effect induced by hydrogen. In contrast, D was found to solely occupy the tetrahedral site owing to the mass effect on the zero-point vibrational energy. This study demonstrates the potential to fabricate hydrides with arbitrary site occupancy by tuning the isotope ratio, which potentially allows for control over their electronic properties and leads to the discovery of novel phenomena.