Principles, developments and recent progress of the phonon confinement model (PCM) for Raman spectroscopy of nanomaterials are reviewed. The evolution of the PCM from a 1-D approximation to a full 3-D treatment with quantum chemical calculations is described. A 3-D PCM analysis of the size-dependent Raman spectra of nanodiamonds and those of the hydrogen-bonding nano-structures in liquid water are discussed. The sizes of the two nano-structures in liquid water, structured hydrogen-bonded water (05nm) and nano-ice (2-4nm), are estimated from the PCM band shape analysis.

CCD and CMOS image sensors have been well accepted in the field of scientific research. This article shows their functions and structures. A MOS-type image sensor was developed in the 1960s in contrast to the CCD-type, which was developed in 1970. It was not popular until the 2000s (for over 30 years) compared to CCD image sensors although MOSs had many advantages. It became popular after 2000 owing to the great achievement of image quality in the mid-1990s. The CMOS sensor actually has many advantages such as low electric consumption and a low price. But there are some disadvantages from the perspective of using it as a measuring tool. This article explains the technical properties of a CMOS image sensor in using it correctly for instrumental purposes.

Atomic force microscopy-based infrared spectroscopy (AFM-IR) is a 'cutting edge' super-resolution technique that combines IR spectroscopy and scanning probe microscopy. AFM-IR provides chemical identification and compositional mapping with spatial resolution far below the diffraction limit of light, i.e. <200nm. This extremely high resolution comes from local detection of thermal expansion of a sample upon IR irradiation via an AFM cantilever tip apex. This paper briefly reviews nanoscale IR analysis in several fields, ranging from polymers, the life sciences, and photonics to solar cells.

Di-magnesium Silicide, Mg₂Si, is attracting much attention as a novel environmentally friendly semiconductor used in high-sensitivity and fast-response short wavelength infrared (SWIR) detectors, because its indirect bandgap energy of 061eV corresponds to the cutoff wavelength of about 2 µm, and the abundance of the constituent elements is suitable for mass consumption. In this paper, we report on the bulk single crystal growth of Mg₂Si, the preparation of a high purity Mg₂Si substrate and the development of a pn-junction photodiode using the thermal diffusion process. The good photoresponse of the photodiode below 2.1 µm confirms the possibility of Mg₂Si as an environmentally friendly SWIR photodetector.

STT-MRAM is a nonvolatile memory using current-induced magnetization switching. For memory usage it is desirable that the switching probability changes sharply from 0% to 100% at the threshold switching current, nevertheless the switching probability changes gradually as the current increases. We could make a physical random number generator, named spin dice, using the controllability of the switching probability from current-induced magnetization switching. The elements of the spin dice are the same as that of an STT-MRAM. Spin dice could become a scalable physical random number generator.

This article introduces the materials development of spin-driven thermoelectric material by using combinatorial experiments, high-throughput ab-initio calculations and interpretable machine learning called a factorized asymptotic Bayesian inference hierarchical mixture of experts (FAB/HMEs).