Reliability engineering is not only a single engineering discipline, but, similar to applied physics, it is also highly interdisciplinary. For equipment to be people-friendly and dependable, it must also have solid reliability. Through cycles of technological development and overcoming reliability issues, high reliability can be achieved. Lack of reliability in systems that require continuous operation may evolve into political or economic problems. In this paper, we present an approach for solving reliability issues that are becoming more and more important every year, and provide specific examples.

Electron spin has a magnetic moment and interacts with a magnetic field through the Zeeman effect. Thus, it has been conventionally controlled by external magnetic fields, such as electron spin resonance (ESR). Spin–orbit interaction (SOI) is a relativistic effect that converts an electric field into a magnetic field; electron spins feel an effective magnetic field depending on the direction of motion by moving in the electric field. In addition, spin and orbital angular momenta are coupled by SOI, therefore, spin up and down are deflected in opposite directions by the spin Hall Effect. These unique features of SOI allow various electrical spin functionality without the use of any external magnetic field. This study reviews the origins of various SOIs along with their spin-related properties and functionalities.

The Japanese company Toshiba invented and developed NAND flash memory, which has been widely used in smartphones such as the iPhone, as well as in USB memory, SD cards, and solid state disks (SSDs). NAND flash memory is compact, lightweight, quiet, impact resistant, and capable of retaining data regardless of whether the power is on or off. Without the invention of NAND flash memory, the widespread use of personal computers and smartphones would have been delayed, hampering the transition to a digital society. Fortunately, a research team of just 10 people at Toshiba invented flash memory in the 1980s. As of 2022, it has developed into a 10 trillion yen market, and we cannot imagine a world without it.

Recently, neutron detection has been applied in various fields, and the development of neutron detectors that are suitable for widespread neutron detection is expected. BGaN has been proposed and developed as a novel neutron semiconductor detection material. BGaN is a ternary nitride alloy that includes B atoms, and is capable of capturing neutrons and detecting signals in a sensitive layer. This report presents a method for the epitaxial growth of BGaN using a new B metal–organic source, TMB, which suppresses gas-phase reactions. By improving the growth conditions, thick growth was achieved and vertical-type thick BGaN pin-diodes were fabricated. The neutron energy spectrum was measured using the fabricated BGaN diodes. The results indicated that BGaN diodes could be used as effective neutron detectors.

Ferroelectrics have been used in a wide variety of applications such as capacitors, memories, and sensor materials. Many ferroelectric materials are solid solutions with complex compositions, and their structures are averaged. In particular, in order to clarify the polarization mechanism of pseudo-cubic structures such as relaxor ferroelectrics, not only average structural analysis assuming a conventional periodic structure, but also local structural analysis must be performed. The pair distribution function method is a technique of local structural analysis in which the radial distribution function is derived from powder X-ray diffraction, and model fitting is performed in real space without assuming a periodic structure. In this paper, the necessity of local structural analysis in dielectrics is discussed.

The gyromagnetic effect is one of the most significant discoveries in physics. It is associated with a mutual conversion of angular momentum between macroscopic mechanical rotation and microscopic electron spin. However, the gyromagnetic field generated by a feasible mechanical rotor is very small for practical applications. Surface acoustic waves are a promising candidate for improving the gyromagnetic effect because an elliptical oscillation of the lattice with a frequency of the GHz order can be realized. In this paper, experimental demonstrations of a gyromagnetic spin-wave excitation and its reciprocal effect, that is, a phase shift of the acoustic wave, are presented. Furthermore, we show that the gradient of the acoustic gyromagnetic field can produce an alternating spin current whose amplitude increases nonlinearly with the frequency.

Among worldwide developments of various quantum-computing hardware platforms, optical quantum computers currently stand out because of their unique approach. Recent progress in optical quantum computing has been remarkable; not only has “quantum supremacy” been achieved by beating supercomputers in specific calculations, but scalable paths to large-scale quantum computers have been discovered. Behind such progress is a new approach that breaks away from the traditional methodology of optical quantum computers. Here, we explain the background of recent progress in optical quantum computers and introduce the development and applications of our original loop-based optical quantum computer based on the new approach.

High-performance permanent magnets are indispensable for everyday life, with applications including hard disk drives, hybrid and electric vehicles, and wind power generators, among others. Recently, their use has expanded to, e.g., small robots and drones, and their demand is increasing each year. In this article, we first present the history of the development of permanent magnets, and revisit the invention of neodymium magnets from a theoretical viewpoint. We then discuss how computational science and data-driven approaches are adopted in the development of permanent magnets.

This chapter discusses compositions, arrangements, and structures of inorganic nanocatalysts that electrochemically promotes material conversion using water as a hydrogen source and introduces the functions of the nanocatalysts. First, the author summarizes the controlling factors of inorganic nanocatalysts applicable to CO₂ reduction reactions, which are regarded as a critical technology for achieving carbon cycling. TiO₂-based catalysts electrochemically produce alcoholic compounds from organic acids and ketones, a new method for highly efficient power storage. Furthermore, thermoelectric conversion and amino acid synthesis on the TiO₂ electrocatalyst are introduced as an advanced application of electrochemical reduction of organic acids and ketones.

Searching for low-friction conditions for moving a microscopic machine is an essential requirement for improving energy savings. The nanotribology of the carbon interface formed by graphene and fullerenes was investigated using frictional force microscopy measurements and molecular mechanics simulation to solve this problem from the viewpoint of nanotechnology. The effects of the loading force, scanning direction, orientation angle, and intercalated fullerene species on nanoscale friction at the fullerene/graphene interface (fullerene molecular bearings) and graphene/graphene interface were investigated. For example, the utilization of the loading force for C₆₀ molecular bearings is expected to lead to the development of a device for controlling the on–off of the superlubric state. The anisotropy of nanoscale friction was analyzed based on the theory of superlubricity. The frictional force is maximized for the commensurate contact of the honeycomb lattice at the interface, and the frictional force rapidly decreases because of an increased lattice mismatch.

Various novel properties are being found in one- and two-dimensional nanomaterials, many of which are considered as promising for photonic applications. However, an issue exists in that the optical interaction cross-section is generally too small, owing to their atomic dimensions. Recently, a number of ways have been proposed and demonstrated for combining them with appropriate nanophotonic platforms to induce strong light confinement, thereby increasing the interactions. This may enable us to employ these novel properties in photonic integrated circuits. This article reviews the results of recent research activities on hybrid nanomaterial–nanophotonic platforms. This technology is promising for future photonic integration, in which we will be able to add various photonic functionalities onto passive Si-based photonic integrated circuits by selectively loading functional nanomaterials.

Nitride semiconductors are used in the active layers of LEDs and lasers with various emission colors. However, problems of decreasing emission efficiency occur at longer wavelengths and with increasing current; furthermore, the mechanisms of radiative and non-radiative recombination processes that govern these phenomena require to be understood. Therefore, the internal quantum efficiency (the ratio of the number of radiatively-recombined carriers to the total number of recombined carriers) must be accurately measured, but doing so is difficult. Furthermore, the measurement method is still being debated. In this paper, we introduce recent progress on the mechanisms of radiative and non-radiative recombination processes in nitride semiconductors and on methods for measuring the internal quantum efficiency.

The introduction of several breakthrough technologies has allowed Cu interconnects to have been used for more than 20 years. While R&D to further extend Cu damascene interconnects to the 2 nm node and beyond continues, alternative interconnect metals such as Ru are being investigated to replace Cu in anticipation of the approaching limit of Cu interconnect technology. This paper outlines the major advances that Cu interconnect technology has made over the past 20 years, and introduces some of the key technologies that are being considered for use in the coming 2 nm generation. Finally, the alternative metal interconnect technologies that are expected to follow the limitations of Cu interconnects will be outlined.

The orbital angular momentum of light associated with a helical wavefront has the capability of twisting several materials without chirality to form exotic chiral structures. This exotic interaction between helical light fields and matters can potentially offer exotic fundamental physical phenomena and advanced photonic technologies to explore new horizons in materials science.

In the last few years, we have seen quantum computer technology reach the level where those processor can be accessed and utilized through internet. As their development has gathered momentum, the notion of what a “quantum computer” is has evolved over time, making it extremely difficult to estimate their technological and readiness levels for real impacts on our society. In this article, we will discuss the current technological status of quantum computers, their possible development paths, and potential technological impact on our current and future society. Specifically, we will compare three alternate development scenarios and explore the effects of our choice for the different development paths on their future impacts.

The EHT project has succeeded in imaging a super-massive black hole at the center of the Milky Way Galaxy. This is the second picture of a super-massive black hole, following the one captured at the center of the elliptical galaxy M87. In this article we will explain the importance of the EHT images, methodology of imaging, and future prospects of the projects.

Two-dimensional materials, including graphene and monolayer transition metal dichalcogenides and their van der Waals heterostructures, have attracted tremendous attention because of the intriguing electronic and optical properties of extreme low dimensionality. The moiré superlattice in twisted van der Waals heterostructure drastically endows novel optical properties and functionality originating from twist angle-dependent electronic properties, offering applications for quantum information and quantum optics. This article introduces the novel optical physics of the moiré superlattice arising from moiré exciton states in a twisted WSe₂/MoSe₂ heterobilayer.

In the field of material development, there has been a paradigm shift away from “manufacturing” based on know-how (experience and intuition) and toward “manufacturing” using artificial intelligence (AI). Here, the critical issue is the development of simulation technology, or the so-called digital-twin technology, which can be used to reproduce a real manufacturing process in a virtual space. This article describes the recent progress in simulation technology, using chemical vapor deposition as an example, which is the basis for the promotion of nanotechnology. It also describes its application to “process informatics,” which is the exploration of manufacturing conditions using AI.

Simple rare earth oxides are usually sesquioxides with stable trivalent rare earth ions, exhibiting highly insulating state. On the other hand, several rare earth monoxides with metastable divalent rare earth ions have been synthesized under high pressure only in 1980s, with the exception of chemically stable EuO and YbO. Recently, we demonstrated that rare earth monoxides can be synthesized by using thin film epitaxy. Thus, it is possible to obtain their first single crystalline or new solid phase materials, enabling to unveil their fundamental properties. In this article, we review recent progress on the synthesis and properties of rare earth monoxides.

In recent years, magnetization control using light has attracted much attention with the goal of realizing next-generation ultrafast magnetic information devices. This paper introduces the results of a study that observed the spin dynamics of a magnetic material after irradiating it with an ultrashort pulse laser. We report how combining laboratory lasers and synchrotron radiation at large facilities revealed the ultrafast spin dynamics.

In this paper, we pioneer “multicrystalline informatics” that links experimental, theoretical, computational, and data science to establish universal guidelines for improving the performance of multicrystalline materials, with the aim to innovate research methods for materials development using multicrystalline silicon as a model material. Moreover, we present the research base that has been established and the new knowledge on the mechanism of dislocation cluster generation that has been obtained through fusion and integration.

Toward efficient electrochemical reactions, we are focusing on the utilization of strong coupling between matter and vacuum electromagnetic fields. We introduce plasmonic control for the confinement of light energy for exotic excitation. In addition, we introduce the use of vibrational strong coupling for the modulation of the properties of water.

Information technology (IT) has been rapidly integrated into many aspects of our daily lives. Semiconductor technology plays a fundamental role in supporting social infrastructure and will continue to be an essential technology that improves the quality of life. In this paper, the history and status of semiconductor technology are briefly reviewed, and future hardware platforms for artificial intelligence are discussed.

Scattering and fluctuation phenomena arise in various fields, from microscopic life activities on the nanometer scale to atmospheric fluctuations on the kilometer one. Understanding and overcoming these phenomena will facilitate breakthroughs in various academic fields, including life sciences, preventive medicine, information and communication engineering, and astronomy. This review article presents an overview of the imaging techniques applied to scattering and fluctuating fields, as part of a new approach that visualizes information inside or beyond scattering media or fluctuating fields by eliminating the effects of scattering and fluctuating fields. More specifically, we introduce imaging techniques to visualize the inside of scattering media and light propagation behaviors in scattering media, to facilitate modeling.

Augmented reality (AR) contact lenses are state-of-the-art display devices. A significant limitation in AR contact lenses is the inability of the eyes to focus on the display device embedded in the contact lens, because the display screen is too close to the eyes. Holographic contact lens displays can address this issue using the three-dimensional image generation ability of holography. This article explains the principle, fundamental experimental results, and device techniques required for the commercialization of holographic AR contact lenses.

In the thrust to achieve carbon neutrality by 2050, tandem solar cells composed of perovskite and hetero-junction crystalline silicon solar cells have attracted much attention as next-generation solar cells, and their conversion efficiencies are approaching 30%. In this article, we show the latest results of the R&D activities for Kaneka’s 2-terminal tandem solar cells, which have a conversion efficiency of nearly 29%, and we discuss the light confinement technologies for tandem solar cells based on optical simulations. In addition, we also introduce 3-terminal tandem solar cells that have the potential to combine the state-of-the-art perovskite solar cells and Kaneka’s world-record holding back-contact-type hetero-junction crystalline silicon solar cells.

A state of the art back-illuminated (BI) single photon avalanche diode array sensor realized through a 90-nm CMOS compatible process on a 300-mm silicon platform is herein reported. The array consists of 10-µm pixels, each using a 7-µm thick silicon active layer, which enables the optical sensitivity of the device to be extended up to the near-infrared spectrum. In addition, buried metal full trench isolation is employed to suppress crosstalk. This is a critical feature in a device sensitive enough to be triggered by a single electro-luminescence photon emitted by a neighboring pixel. Finally, to maximize the fill factor and enable a BI structure, a Cu–Cu bonding process is conducted.

Seebeck effects, the generation of voltages from temperature gradients via thermal electron motion, have been applied to temperature sensors and power generators that convert thermal energy into electricity. Recently, the electron-spin counterpart of the effect — the spin Seebeck effect — was discovered in spintronics, which generates a thermoelectric voltage from electron-spin fluctuation through a spin current. However, these effects have been limited to electrons, and they inevitably disappear at low temperatures due to electronic entropy quenching. In this article, we report thermoelectric generation driven by nuclear spins in a solid, that is, the nuclear-spin Seebeck effect. The sample is a magnetically ordered material, MnCO₃, having a large nuclear spin (I = 5/2) of ⁵⁵Mn nuclei with a Pt contact. In the system, we observed low-temperature thermoelectric signals reduced to 100 mK owing to nuclear-spin excitation. Theoretical calculation show that the interfacial Korringa process plays an important role. The nuclear thermoelectric effect described here provides an approach for exploring thermoelectric science and technologies at ultralow temperatures.

Anisotropic self-assembled nanomaterials in transition metal compounds have attracted much attention because of their rich physical properties and structural controllability. Although peculiar sample preparation conditions and high-temperature processing are generally necessary for fabricating anisotropic nanostructures in oxides, nanometer-scale spinodal decomposition in spinel-type manganese oxides results in highly ordered nanostructures through simple heat treatment at relatively low temperatures. In this paper, we introduce recent studies on the formation of checkerboard and lamellar nanostructures comprising Mn-rich tetragonal and Mn-poor cubic nanodomains in manganite spinel (Co,Mn,Fe)₃O₄ annealed at 375 °C.

Ferroelectrics can function as non-volatile memory thanks to their switchable electric polarization by an electric field. However, realizing ferroelectricity at ultrathin thicknesses remains a challenge in materials science. To tackle this challenge, we artificially created a two-dimensional ferroelectric material using the van der Waals assembly. By manipulating its stacking order, we successfully transformed boron nitride, a non-ferroelectric van der Waals compound, into a ferroelectric material. The resulting ferroelectrics are stable up to room temperature despite their sub-nanometer thickness, enabling non-volatile memory applications. We further demonstrated the versatility of the design principle by converting semiconducting transition metal dichalcogenides into ferroelectrics in a similar manner.

When device scaling reaches the limit imposed by atoms, technology based on atomically precise structures is expected to emerge. In this technology, the assembly of building blocks with identified atomic arrangements without contamination plays a key role. We propose a transfer technique for deterministic fabrication of carbon-nanotube-based optical devices. By using single-crystalline anthracene as a medium, which can form large-area thin films, clean nanotubes are placed on a wide range of substrates. Under in-situ optical monitoring, nanotubes of desired chirality can be placed onto the desired location with sub-micron accuracy. This paper introduces the details of the transfer technique, followed by a few examples of the deterministic construction of heterostructures consisting of nanotubes with defined atomic arrangements and other nanomaterials/nanostructures.

Moiré lattice systems of two-dimensional (2D) materials, which are superlattices based on the moiré interference of crystal lattices, have garnered attention as a new platform for examining the many-body physics of electrons and excitons. Transition metal dichalcogenides (TMDs), which are 2D semiconductor materials, are considered as potential candidates for hosting correlated electrons in moiré lattices because of their relatively heavy mass. Although excitonic properties of TMDs have been extensively studied through optical measurements, the electronic properties of moiré lattice systems remain unexplored owing to the challenges of transport measurements. This study was focused on the recent discovery of strongly correlated electronic states in semiconductor TMD moiré lattice systems using exciton resonance in optical spectroscopy.

Active removal of the generated heat is necessary in many situations, such as in power semiconductors, CPUs in data centers, batteries, and heat engines. Existing thermoelectric conversion methods mostly use heat that has been ejected from the system and hence is utilizable without particular obligations. However, the integration of active cooling with thermoelectric power generation had not been explored previously. Since 2015, we have been creating and studying a new technology that integrates liquid-based thermoelectric conversion with forced convection cooling. In this report, we describe the concept of this technology and summarize our recent results.

Intensive research is being conducted to further improve the performance of lithium-ion secondary batteries. Conventional cathode materials exhibit excellent charge-discharge cycle characteristics because only Li ions are extracted and inserted while maintaining the crystalline structure of the material. In contrast, lithium-rich layered oxide (LLO) materials with a low-crystalline structure have achieved high energy density and extraction/insertion of a large amount of Li ions. Herein, the existence of a low-crystalline phase in the LLO structure, formed by a crystal structure change accompanying the migration of pillar metal ions that support the Li deficient layer during extraction of Li-ions, is revealed by pair distribution function (PDF) analysis.

Nickel oxide (NiO) is a wide-bandgap oxide semiconductor and functional material that offers advantages including p-type conductivity, a high absorption coefficient, and a relatively small ionization potential. It is, therefore, a promising material for use in novel applications such as “invisible” solar cells, sensors, transistors, and hole-injection layers. This study examined the fundamental properties of NiO thin films deposited using conventional RF magnetron sputtering. In addition, several devices transparent to visible light using NiO, including solar cells, Internet of Things monolithic gas sensors, and self-powered devices, have been introduced, and the robustness of such devices, including radiation resistance, was investigated.

This study aimed to develop wireless multi-modal and multi-tasking flexible sensor sheets. To realize multimodal flexible sensor, various sensors using low-cost solution-based process were proposed for integration on flexible films. In particular, monitoring of continuous vital signals was demonstrated by attaching a sensor sheet to a human. For multitasking systems to make X-in-1 sensors, reservoir computing, which is one of the machine learning techniques, was applied to a flexible sensor. As a proof-of-concept, weather sensors that detect the rain droplet volume and wind velocity were developed. Although there are remaining issues that must be resolved to realize practical devices, the proposed method can be used to build a multimodal and multitasking low-power sensor system in the future.

Plasma–material interaction (PMI) refers to phenomena that occur at the interface between the plasma and solid surfaces. The plasma, which has high energy and low density, facilitates the formation of nanometer-scale structures on solid surfaces. Nanotechnology is supported by the PMI. In nuclear fusion research, plasma-induced microscopic changes in solid surfaces of the inner wall of the vacuum vessel are important issues. For instance, the reaction product of helium plasma induces a fuzzy nanostructure on a tungsten surface. In PMI, while focusing on spatially microscopic changes, the plasma irradiation time is extremely long, ranging from seconds to hours. Certain elementary processes occur on microscopic time scales; however, to elucidate the entire process, the PMI must be regarded as a special subject in microscopic space and macroscopic time. From this perspective, this study introduces the difficulty and interest in the numerical simulation of PMI for future efforts.

A copper chalcopyrite compound CuGaSe₂ (CGS) thin film is a promising material for application to photoelectrochemical (PEC) water splitting into hydrogen (H₂). In this article, we first review the operating principle and measurement methods of PEC water splitting using semiconductor-based electrodes before reviewing studies on PEC H₂ evolution over CGS-based photocathodes. The requirements of surface modifications of the CGS thin film with a CdS layer and nanoparticulate Pt catalysts for realizing efficient PEC H₂ evolution are then introduced. Moreover, the effects of insertion of a Cu-deficient layer between the CGS film and the CdS layer and doping of Rb components into the CGS film for improving PEC properties are discussed. Finally, a critical problem of current CGS-based PEC devices for their practical applications, i.e., poor disabilities under an operating bias, is discussed.

Giant magnetic responses and magneto-thermoelectric phenomena emerging in topological materials hold promise for applications in the next generation of electronics. Inspired by the remarkable properties in crystals of a topological ferromagnet Fe₃Sn₂, we have been involved with developing Hall devices using amorphous-like thin films of a ferromagnetic alloy of Fe_0.6Sn_0.4 as a more versatile material form. The amorphous-based device is composed of inexpensive and environmentally benign elements, potentially offering new applications that take advantage of the high temperature stability of the device itself and the mechanical flexibility of the metallic film. As the magnetoresistance effect specific to magnetic materials can be measured simultaneously with the anomalous Hall effect, this device can be applied to the detection of three-dimensional (3D) magnetic field vector with a single planar-type structure. In this paper, we overview the operating principles of various thin-film magnetic sensors and introduce the fabrication method and basic properties of Fe–Sn amorphous-like thin films as well as the principles and characteristics of two devices: a cross-shaped Hall device and a planar-type 3D magnetic field sensor.

Effective solar energy utilization is extremely important in realizing a carbon neutral society. Therefore, a power generation technology that can utilize the full spectrum of sunlight is required. Solar energy conversion based on thermophotovoltaics (TPVs), called solar-TPV, potentially enables the use of the full spectrum of sunlight and high-efficiency conversion with single-junction cells. Here, we introduce a technology for controlling the thermal radiation spectrum (which is important for achieving high-efficiency solar-TPV), as well as the results of experiments using a designed solar-TPV system. In addition, we describe the prospects for advanced solar energy utilization by solar-TPV.

In recent years, the number of studies that include the terms “data-driven research” and “informatics” in their titles has increased, and efforts toward DX (Digital Transformation) with high-throughput and autonomous experiments have become active. While the materials and sample morphologies to be studied are wide-ranging, we have focused on multinary oxide powders and engaged in the development of methods leading to informatics research, such as automated preparation of powder samples based on liquid phase processing, fast powder X-ray diffraction, tools for characterization of physical properties and tools for synchrotron powder diffraction.

Aluminum (Al) alloys are widely used as lightweight structural metals and are increasingly being applied to various components such as transportation equipment. This study describes a novel corrosion protection method of for Al alloys using steam, called the steam coating process. The process involves the formation of hydroxide crystals on the surface of the Al alloy, which increases its corrosion resistance by acting as an anticorrosive film. At the same time, precipitation hardening can be achieved by utilizing the steam’s thermal energy, increasing the strength of the alloy. This study will provide examples of the multi-functionalization of Al alloys through the steam coating process.

An interactive interface between computational data and real biomolecules, such as a mixed reality technology, can potentially contribute to the next generation of nanomolecular machines and computing. Herein, we develop a virtual cathode display as a molecular-resolution mixed reality interface, which can exhibit electric field phenomena in a dynamical nanopattern. A thin membrane window of SiN is employed as a display surface for the presentation of electric field. Backside projection of a scanning focused electron beam generates nanoscale electric, chemical, and mechanical phenomena on the SiN surface. This projection pattern can be instantly refreshed in response to changes in target biomolecules and living cells in an aqueous solution.

To meet the increasing needs to automate cell culture handling, including separation, purification, and collection, we examined the use of photo-responsive polymer materials as culture substrates. Accordingly, we developed a polymer that becomes water-dissoluble in sharp response to light irradiation, and demonstrated photo-selective cell detachment and collection from the polymer-coated substrate. In addition, selective cell killing and cutting of cell monolayer was implemented using the polymer material, which generates acid/heat upon light irradiation. Some of these technologies were applied to the purification of undifferentiated cells and the sectioning of cell monolayer in the maintenance and culture of human iPS cells.

The structure and function of complex neuronal networks in the brain can be partially reconstituted in vitro by integrating cell culture and microfluidic device technologies. In this report, we review our recent studies on developing microfluidic devices to reconstitute small neuronal networks bearing a modular structure, which is a canonical structure found in the nervous systems of animals. We also describe the process of recording functional activity from the reconstituted neuronal networks. These fundamental technologies offer novel tools for investigating structure–function relationships in living neuronal networks and exploring the physical basis of biological computing in the brain.

Optogenetic techniques, in which neural activity can be controlled by irradiating light from outside, are used to understand brain function. In recent years, there has been a growing demand for techniques to irradiate light to multiple specific neurons spread throughout the brain tissue in order to elucidate more advanced brain functions with complex neural networks. However, it is difficult to irradiate specific areas or multiple areas simultaneously using conventional light irradiation techniques such as optical fibers or microscopes, and their use in freely behaving animals is limited. In this paper, we introduce our MicroLED neuroscience probes that can be applied to a deep brain region and a wide area of the cerebral cortex.

Transition metal chalcogenides (TMCs) have attracted significant attention in recent years owing to their diverse nanostructures and physical properties. In particular, the progress of growth techniques has enabled the efficient preparation of high-quality two-dimensional (2D) layered TMCs, as well as various one-dimensional (1D) TMCs, such as nanotubes, nanoribbons, and nanowires. In this study, we focus on 1D TMC wires. An overview of recent progress in this area and our findings on vapor-phase growth of isolated single TMC wires and large-area networks of TMC wires are presented.

Semiconductor devices are inherently sensitive to radiation, exhibiting malfunctions called soft errors. Although a soft error is sometimes misunderstood as an old and settled issue, it still makes marked negative impacts on our social and economic activities. Today’s testing of soft-error reliability relies heavily on exposure to radiation. Regardless of whether an effort aims for space or terrestrial applications, the reliability of a chip is hardly known until tested with radiation. As a soft error is triggered by energy deposition from radiation, the bombardment of radiation seems essential and unavoidable in the test—Is it really true? The present study is challenging this question. The authors are exploring equations capable of assessing soft-error reliability proactively—as if by magic—without using radiation.

Substantial amounts of low-temperature waste heat are emitted from objects of various shapes and remain unused. Flexible thermoelectrics have garnered considerable attention for the efficient conversion of waste heat into electricity. Such flexible materials feature numerous van der Waals (vdW) interfaces. Thus, a basic understanding of the thermoelectric properties of vdW interfaces is crucial for enhancing the thermoelectric performance of flexible thermoelectrics. Herein, we present the results of our systematic study pertaining to the thermoelectric properties of single-walled carbon nanotubes as a thermoelectric model with vdW interfaces and discuss their future potential.

In the universe, abundant nanoparticles exist, and they serve pivotal roles in various environments. Nevertheless, their formation processes are still unclear. We have been conducting experiments to elucidate the nucleation processes from the gas phase, believing that the key to understanding material evolution in the universe lies in characteristic properties at the nanoscale. Consequently, we discovered that dimer formation and decreasing melting point are key factors for homogeneous nucleation from the gas phase. Additionally, particle-mediated growth is crucial for dust formation. Herein, we present some of our recent results.