I consider problems in the references to the history of Buraku in J. M. Ramseyer’s article, “On the Invention of Identity Politics: The Buraku Outcastes in Japan”, published in Review of Law and Economics in 2019. As a researcher on the history of those who had been subjected to discrimination in the early-modern era, mainly in East Japan, I would like to point out problems in the article, focusing on its references to and quotations from previous works.

In this proceeding paper, we introduce the recent results of Galactic maser astrometry by mainly focusing on those obtained with Japanese VLBI array VERA. So far we have obtained parallaxes for 86 sources including preliminary results, and combination with the data obtained with VLBA/BeSSeL provides astrometric results for 159 sources. With these most updated results we conduct preliminary determinations of Galactic fundamental parameters, obtaining R0 = 8.16 ± 0.26 kpc and Θ0 = 237 ± 8 km/s. We also derive the rotation curve of the Milky Way Galaxy and confirm the previous results that the rotation curve is fairly flat between 5 kpc and 16 kpc, while a remarkable deviation is seen toward the Galactic center region. In addition to the results on the Galactic structure, we also present brief overviews on other science topics related to masers conducted with VERA, and also discuss the future prospect of the project.

A nonlinear circuit model (NCM) with physical parameters is proposed for direct simulation of the RF characteristics of GaN high-electron-mobility transistors (GaN HEMTs) on the basis of device structure. The physical equations are used for the construction of the model in order to connect strongly the model parameters with the device/physical parameters. Hyperbolic tangent functions are used as the model equations to ensure good model convergence and rapid simulation (short simulation time). The usefulness of these equations is confirmed by technology computer aided design (TCAD) simulation. The number of model parameters for the nonlinear components (Ids, Cgs, Cgd) is reduced to 17 by using common physical parameters for modeling the drain current and capacitance. The accuracy of this model is verified by applying to GaN HEMTs. The modeled I–V and capacitance characteristics agree well with the measurement data over a wide voltage range. Furthermore, this model can be used for the accurate evaluation of S-parameters and large-signal RF characteristics.

An amorphous p-type conductive oxide semiconductor was created based on a mother crystalline material, a p-type conductive ZnRh2O4 spinel. The amorphous film of ZnRh2O4 was deposited by an rf sputtering method. Seebeck coefficient was positive, +78 μVK-1, indicating that major carrier is a positive hole. A moderate electrical conductivity (2 S cm-1 at room temperature) for a p-type semiconductor was observed. Optical band gap was estimated to be 2.1 eV. P-n junction diodes with a structure of Au / a-ZnRh2O4 / a-InGaZnO4 / ITO fabricated on glass substrates, operated with a good rectifying characteristics, a rectification current ratio at ± 5V of ∼103. The threshold voltage was 2.1 eV, which corresponds to the band gap energy of the amorphous ZnRh2O4. This is the first discovery of a p-type amorphous oxide and the demonstration of p-n junction all composed of amorphous oxide semiconductors.

Several Cu(I)-containing layered oxysulfides were selected as candidates for wide-gap p-type semiconductors by extending a concept of a materials design for transparent p-type conducting oxides. The electrical and optical properties of the selected oxysulfides were investigated, and their electronic structures were analyzed by energy band calculations. LaCuOS, Sr2Cu2ZnO2S2 and Sr2CuGaO3S were found to be wide-gap p-type semiconductors, and LaCuOS showed the largest energy gap (Eg=3.1eV) among these layered oxysulfides. It was also found that LaCuOS shows band edge emission under uv excitation at room temperature, which is consistent with the results of the energy band calculations that LaCuOS has a direct-allowed-type energy gap at Γ point. In further materials research, analogous layered oxychalcogenides such as LaCuOSe and LnCuOS (Ln=Pr, Nd) were found to show similar optical and electrical properties to those of LaCuOS. Therefore, it is considered that the layered crystal structure and the electronic structure are responsible for the wide-gap p-type conductive properties in these materials.

A transparent oxide semiconductor with delafossite structure, CuInO2, was found to exhibit both p-type and n-type conduction by doping of an appropriate impurity and tuning of proper film-deposition conditions. Thin films of Ca-doped or Sn-doped CuInO2 were prepared on -Al2O3 (001) single crystal substrates by pulsed laser deposition method. The films were deposited at 723 K in O2 atmosphere of 1.0 Pa for the Ca-doped films or 1.5 Pa for the Sn-doped films. The positive sign of the Seebeck coefficient demonstrated p-type conduction in the Ca-doped films, while the Seebeck coefficient of the Sn-doped films was negative indicating n-type conductivity. The electrical conductivities of Ca-doped and Sn-doped CuInO2 thin films were 2.8×10−3 S·cm−1 and 3.8×10−3 S·cm−1, respectively, at 300 K. The optical band gap of each film was estimated to be ∼3.9 eV. Since CuInO2 exhibited bipolarity in electrical conduction, transparent p-n homojunctions based on CuInO2 were fabricated on (111) surface of yttria-stabilized zirconia single-crystal substrates. The structure of the diode was In2O3:Sn / n-CuInO2:Sn / p-CuInO2:Ca / In2O3:Sn electrode on the substrate. The contact between the n-and p-type CuInO2 semiconducting oxides was found to be rectifying. The turn-on voltage was ∼1.8 V.

High quality ITO thin films were grown hetero-epitaxially on extremely flat substrate of (001) YSZ by a pulsed laser deposition technique at a substrate temperature of 600°C. The crystal orientation relationship between the film and YSZ were confirmed as ITO (001) // YSZ (001) and ITO (010) // YSZ (010), respectively, by HR-XRD and HR-TEM. The carrier densities of the films were almost equal to Sn02 concentration in the films. That is, almost all the doped Sn4+ ions were activated to release electrons to the conduction band. The carrier densities of the films were enhanced up to 1.9×1021cm−3, while the Hall mobility showed a slight, almost linear, decrease from 55 to 40cm2V−1s−1 with increasing SnO2 concentration. The low resistivity is due to larger electron mobility, which most likely resulted from good crystal quality of the films. The optical transmissivity of the film exceeded 85% at wavelengths from 340 to 780nm.