Defect structure-type proton conductors are ceramics in which hydrogen ions (protons) dissolve in oxides and diffuse in the crystal. The material has attracted much attention as an electrolyte for hydrogen sensors and fuel cells. In this review, the material properties and polarization characteristics of defect structure-type proton conductors will be explained, and the application to hydrogen sensors and fuel cells will be introduced.

The radio wave protection guidelines and evaluation methods for human safety assessment of wireless power transmission using microwaves are described. Microwave power transmission has been institutionalized among wireless power transmissions, and human safety evaluation is required for its operation. This paper introduces what radio wave protection guidelines are, how they are evaluated, and trends in international standardization.

Market trends call for higher performance and lower cost Micro electro mechanical systems(MEMS). We have focused on material technology and have achieved single-crystallization of lead zirconate titanate (PZT) thin film, which is a piezoelectric material, and have introduced it to the market. The single-crystallization of piezoelectric thin film provides various advantages such as high piezoelectric constant, low permittivity, high reliability, and temperature stability, and is expected to contribute to the development of piezoelectric MEMS devices in the future. In addition to PZT, this technology also shows the possibility of single-crystallizing various other piezoelectric films. This paper introduces the development and manufacturing of piezoelectric MEMS, focusing on the single-crystallization technology of piezoelectric films.

In the era with rapid development of quantum devices, the next milestone to be achieved is to surpass the performance of classical computers with quantum computers in practical problems, that is, to achieve quantum advantage. In this work, we introduce recent research that argues that the main field for this purpose is envisioned to be condensed matter physics. The main contributions of the relevant paper are summarized in three points: (1) proposal of a method for analyzing the execution time of classical computation algorithms based on the tensor network method, (2) evaluation of the execution time of fault-tolerant quantum computation algorithms at the instruction level, (3) discovery of a quantum acceleration region in two-dimensional strongly correlated quantum many-body systems. The lattice model discussed in this paper is expected to play a guiding role in the research and development of fault-tolerant quantum computers, as it requires fewer resources in terms of the number of qubits and execution time than other known platforms for quantum advantage.

Transition metal dichalcogenides (TMDs), atomically thin layered materials, were attracted intense attention due to its outstanding optical and electrical features. In spite of recent progress in production stage, it is still needed to be improved the quality of TMD crystal. Elucidation of detailed growth mechanism should be important to solve this critical issue in TMD crystal growth. Based on this background, we developed in-situ monitoring CVD, which can directly observe the detailed crystal nucleation and growth dynamics of monolayer and single crystal TMD. Here, we show the recent findings about growth mechanism of TMDs revealed by our study such as diffusion length of precursors, non-classical nucleation, and liquid-solid transfer growth together with their theoretical background.

Recently, moiré superlattice systems, which are formed when atomically thin layered materials are stacked with arbitral angle, have attracted much attention because of their unique physical properties. On the other hand, there are still many unresolved issues concerning phonon properties and the thermophysical properties. In this paper, we introduce our study on the thermal conductivity measurement depending on the stacking angle of a suspended moiré superlattice system by using Raman spectroscopy.

The charge pumping method is a technique used to evaluate oxide/semiconductor interface traps in MOSFETs. The interface trap density is calculated from the substrate current flowing when repetitive pulses are applied to the gate. The charge pumping characteristics of MOSFETs using new materials are often quite different from those of Si MOSFETs due to the high trap density at the interface and/or in the oxide. Here, we introduce the key points of evaluating the interface characteristics using the charge pumping methods, including the effect of pulse condition and MOSFET structure, and the use of a 3-level pulse, focusing on the measurement results of SiC MOSFETs.