In this paper, we analyze and quantitatively compare the electron density distribution along the sheet thickness of quantum wells formed in the finite and infinite potential barrier cases, assuming a nanosheet structure consisting of a 5 nm thick Si sheet and HfO₂ insulator. The maximum electron density in the finite well case is about 33% larger than in the infinite well case, and the electronic areal density is about 52% larger than in the infinite well case. The electron penetration distance into the insulator is 0.160 nm, which correspond to effectively increasing the sheet thickness by 6% for a sheet thickness of 5 nm. Additionally, for a device with EOT of 0.5 nm, the penetration is accounted for about 5.7% of the insulator thickness. The penetration distance is 0.036 nm larger than that of the previous work of Barker et al. Also, the electronic areal density in insulator range is 1.4 times larger than that of the previous work. It is found that the previous method is underestimated the electron penetration into the insulator.

In this paper, we have analyzed sheet thickness and gate voltage dependence of electrical characteristics for nanosheet MOSFETs using a device simulation that takes quantum confinement effects into account. Since the sheet thickness of nanosheet MOSFETs decreases to several nanometers, the simulated on-current shows significant reduction compared to the on-current required in the device design due to the quantum confinement effect. We analyze the relative difference between the on-current required in the device design and the simulated on-current and propose a design guideline using the relative difference. In order to suppress the relative difference of the on-currents within 3%, the minimum sizes of the sheet thickness are 3.4, 4.5, and 5.5 nm at supply voltages of 0.70, 0.60, and 0.50 V, respectively.

In this work, we propose an analytical model for predicting the peak position of electron density in Nanosheet MOSFETs. Quantum drift diffusion model is used to examine the distribution of electron density. Specifically, we investigate the gate voltage dependence of the electron density peak position for varying sheet film thicknesses, considering the analytical model for each thickness. Our investigation focuses on sheet film thicknesses of 10nm and 4nm. The results indicate that for the film thickness of 10nm, two electron density peaks are integrated at the center when the gate voltage is 0.4 V, whereas for the film thickness of 4nm, two peaks are integrated at the center with a gate voltage of 0.7 V. Utilizing the simulation results of electron density distribution, we estimate the parameters of the analytical model equation for both film thicknesses. Subsequently, we evaluate the estimated results by comparing them with the simulation results. The analytical model shows an accuracy with only 5.53% discrepancy from the simulation results for the film thickness of 10nm and only 4.01% discrepancy for the film thickness of 4nm.

This paper analyzes stability of a grid-following inverter by the complex vector control in αβ domain and by the PLL synchronization control in dq domain. It is known that the frequency transfer function of the PLL may affect mutual interactions between grid and line impedances. This paper analyzes frequency characteristics of the inverter based on the mixed-domain control for stability by the impedance method. Considering frequency coupling effects by the PLL control, it is found that the passivity of the inverter is violated and it may become unstable for a weak grid. This result is validated by analytical derivation, simulation, and experiment.

A novel technique that manipulates tiny objects using electrostatic forces is proposed. This technique, which has grid-structure electrodes, potentially can drive multiple objects individually. One of the possible applications is precise sorting of small plastic pieces by materials or colors. The dielectrophoretic force that is generated by concentrated electric field is mainly utilized in this technique. In this study, the effect of a protrusion attached at the cross-point of the grid was investigated using a single-cross device which is a basic structure of this technique. A glass sphere with approximately 1.2 mm diameter was used as a model for target objects. The driving force exerted on the target was determined with high-speed photography of the trajectories, along with numerical simulation. It was elucidated that the electric field concentrated by the protrusion enhanced the forces directing to the cross point. At the same time, the comparison with the simulation of the dielectrophoretic force and the calculation of the field strength suggested that a little amount of charge generated by discharge affected the driving force. Moreover, the transfer of the glass sphere between two cross-points with the interval of 2 mm in approximately 300 ms was successful.

For the application of thermochromic smart windows, it is important to realize high visible light transparency, modulation of infrared transmission, and phase transition temperature around room temperature. For this purpose, vanadium dioxide (VO₂) thin films co-doped with niobium and zirconium were synthesized by metal-organic decomposition (MOD) method on glass substrates. First, the effect of Zr doping on the transparency of VO₂ thin films was investigated as a preliminary experiment. 3 mol% Zr doping improved the visible light transmittance of VO₂ thin films from 49% to 56%, and the phase transition temperature decreased from 81°C to 74°C without decreasing the switching ratio in the infrared region. Then, the effect of Zr and Nb co-doping on the transition temperature of VO₂ thin films was investigated. The VO₂ thin film co-doped with 3 mol% Zr and 4 mol% Nb could significantly decrease the phase transition temperature from 74°C to 48°C while nearly maintaining the visible light transmittance.

Hyperdoping of semiconductors with deep impurities is a promising method to form intermediate bands. Hyperdoped semiconductors can be prepared by ion implantation followed by pulsed laser melting. However, since hyperdoping is a nonequilibrium process, the correlation between the hyperdoping process and the physical properties of the hyperdoped semiconductor is not clear. In this study, we investigated the correlation between the hyper doping process and optical absorption and pn junction properties by hyperdoping of Si with S.

We have successfully grown monoclinic (β) phase single-crystalline molybdenum trioxide (MoO₃) films on a lattice-matched (LaAlO₃)_0.3-(SrAl_0.5Ta_0.5O₃)_0.7 (LSAT) substrate with a 5-nm-thick WO₃ buffer layer by molecular beam epitaxy (MBE). We investigated the structural changes and electrochromic properties of a 40-nm-thick β-MoO₃ film prepared by proton injection for smart window applications. Proton injection into the film up to 12 mC/cm² resulted in the formation of cubic H_0.99MoO₃ with an associated significant reduction in transmittance in the visible to near-infrared range. The coloration efficiencies at λ = 650 and 1000 nm are ∼32 and ∼65 cm²/C, respectively. Such high values are due to the unique properties of the high-quality β-phase MoO₃ epitaxial thin films. X-ray photoelectron spectroscopy measurements showed that Mo⁵⁺ and Mo⁴⁺ related peaks appeared simultaneously owing to protonation, which may have introduced oxygen vacancies into the molybdenum bronze. Our results provide valuable information for the application of MoO₃-based electrochromic devices.

The recent development of wireless communication technology has increased the risk of electronic equipment malfunctions and information leaks. To address this issue, we developed and evaluated a lightweight and flexible electromagnetic shielding material that can be applied to wearable devices by combining carbon nanotubes and elastomer materials.

We have investigated a transfer process for fabricating flexible thin films of hexagonal crystal systems. In this report, we proposed a transfer process utilizing the dissolution of ZnO and Sr₃Al₂O₆ (SAO) multilayer, such as hydroxyapatite, on a flexible polymeric sheet. The diffraction peaks of both ZnO and SAO were clearly observed in the fabricated samples, while only the ZnO diffraction peaks were detected in the samples lifted-off from the original substrate. Furthermore, immersing the samples in a mixture of 60 vol.% methanol and 40 vol.% acetylacetone, which dissolves ZnO, resulted in the disappearance of ZnO diffraction peaks. This result indicates that the proposed process of dissolving ZnO/SAO multilayers is practical for the transfer of hexagonal crystal systems.

CO₂ sensor device using thin film transistor (TFT) structure is attracting attention from the viewpoint of gas sensitivity and low power consumption because CO₂ monitoring everywhere is required in various fields. Oxide semiconductors are used as its channel material, however, the correlation between electrical properties of oxide thin film and gas sensitivity in TFT-type gas sensor has not been clarified, thus far. In this study, we fabricated InZnO TFTs with different composition ratios of In₂O₃ and ZnO, and investigated the influence of their electrical properties on CO₂ sensitivity. In terms of the TFT properties, InZnO with a Zn content of 31% showed the best field-effect mobility. This is because the addition of Zn generated more oxygen vacancy and increased carrier density. On the other hand, further increasing Zn content, the electrical properties deteriorated compared to non-doped In₂O₃ and the maximum activation energy increased. For CO₂ sensing, the sensitivity improved as the Zn composition ratio decreased, and thus the non-doped In₂O₃ TFT showed the highest performance. We believe that adsorption of gas molecules becomes more effective when an oxide semiconductor film has both smaller activation energy and moderately high carrier density.

Nitrogen (N) has attracted attention as a hole dopant for SnO_x semiconductors. We have previously reported p-type conversion of n-type SnO₂ thin films by N doping by thermal annealing in N₂ atmosphere. Since the diffusion length of N is several 10 nm order, uniform N doping in the film is limited in terms of practical applications. In this study, we investigated N doping into the bulk using RF magnetron sputtering in Ar/N₂ mixed gas atmosphere. N-doped SnO₂ (SnO₂:N) thin film was fabricated by the sputtering at a substrate temperature of 300°C and a N₂ concentration varied between 25 and 80%. The fabricated thin films were amorphous under all deposition conditions. As the N₂ concentration increased, the absorption edge shifted to the longer wavelength and optical bandgap became narrower. XPS and PL analyses showed that as oxygen vacancy decreased, Sn-N bonding and N^3- component, which acts as an acceptor, increased. Hall-effect measurement showed the SnO₂:N deposited at 80% N₂ concentration has p-type conduction. We believe that this is because increase in density of states of N 2p orbital. However, the mobility was 0.12 cm²/Vs, suggesting limitation in improvement of electrical properties even in N doping into the bulk.

Visible-light-activated TiO₂ photocatalysts based on the localized surface plasmon resonance phenomenon were synthesized. Pulsed laser ablation and rapid heat treatment were used to deposit Ag nanoparticles supported on lower anatase TiO₂ films as the main photocatalysts and upper TiO₂ films as the passivation films to prevent chemical reaction of the Ag nanoparticles. Optical properties and photocatalytic activities were evaluated. It was found that the visible light (410 nm) photocatalytic activities were increased with decreasing thickness of the upper TiO₂ films.

The high peak intensity of femtosecond lasers can cause multiphoton absorption of material near its focal point. Thus, microfabrication inside the transparent solid material becomes possible. Transparent materials are not limited to solids, and it has been reported that micro/nanoparticles can be also synthesized near the focal point inside the transparent liquid material. In this paper, we investigated the synthesis of microparticles in a highly viscous transparent liquid using silicone oil. As a result, transparent carbon microparticles were synthesized when the wavelength of femtosecond laser was converted to 520 nm, and the microparticles might contain carbon nanocrystals due to graphitization.

Aiming to expand the application range of photodynamic therapy, we investigated Gd₂O₃:Er,Yb as a sintered raw material for the synthesis of upconversion nanoparticles and the effect of the sintering temperature, which is important because of its large effect on luminescence. Increasing the sintering temperature of the raw material resulted in a higher emission intensity because of higher crystallinity. Moreover, although the primary particle size of the raw material increased with temperature, the crystal structure remained unaltered. Because raw materials hardened at high temperatures, higher laser fluence was used to fabricate nanoparticles to reduce size via laser ablation in liquids.

The purpose of this study is to consider the difference in the characteristics of conducting waves depending on the electrode width and direction. The electrodes proposed array electrodes that have five electrodes with widths of 10, 9, 8, 7, and 6 mm arranged in a fan shape. By incorporating a DIP switch between the electrode and the amplifier and turning it ON (short circuit), it is possible to change the electrode shape without replacing it. The analysis used the multi-channel method. As a result, when all are short-circuited, it is possible to estimate the mixing of noise in each channel. It was found that an averaged conducting wave can be obtained by widening the electrode width. In addition, from the result of more conducting waves can be extracted from the electrodes attached in the direction of the muscle fibers, it is possible to estimate the direction of the muscle fibers.

In this study, we focus on "editing" in film expression and examine its dramatic effect. Editing is not simply a process of rearranging multiple video materials that have been shot, but it is an expressive act that produces dramatic effects. In this study, we hypothesized about the possibility of changes in the effects of editing by the difference in the duration until the video materials are switched. Based on the hypothesis, we conducted a questionnaire survey twice through the comparison of videos that were edited differently, and conducted a quantitative analysis of the results of the written responses using text mining. Through the two surveys, we found that editing affects the two evaluation axes of "quality of direction" and "quality of the movie-viewing experience" in the quality of film works as perceived by viewers, and that adjusting the duration of video materials has a directing effect that affects "quality of the movie-viewing experience" in particular.

This paper describes an analysis of EEG signals during the recall of computational load task (or mental arithmetic). For this purpose, feature values were extracted from measured data from multiple EEG electrodes (F3, F4, FC3, etc.) under two conditions: resting state and mental arithmetic image recall state. When we applied SVM (Support-Vector Machine) using features obtained from brain wave component ratios of 20 subjects, the classification accuracy was 72.8%. Subsequently, to correct the classification accuracy, we focused on the heart rate, which reflects the balance of the autonomic nervous system. As a result, when excluding individuals with relatively fast heart rates from the dataset based on their resting state, the classification accuracy improved with results up to 90.2%. Furthermore, when excluding individuals with relatively slow heart rates from the dataset, the classification accuracy decreased to less than 60%.

This letter proposes a normalization method in decomposition-based constraint handling techniques for constrained optimization. The proposed normalization method has robustness against scale differences between the objective function and constraint violation while the conventional method loses it. Numerical experiments confirm that the proposed normalization method has better search performance than other methods.

It would be useful to be able to detect abandoned BLE (Bluetooth Low Energy) devices or suspicious BLE devices in the surrounding area. In this letter, we propose and develop a system that supports grasping of nearby BLE devices using a smartphone. Our proposed system can support obtaining a list of MAC addresses of nearby BLE devices and identifying devices with each MAC address by bringing the smartphone closer to a device. In this letter, we conducted a basic evaluation of our proposed system through experiments using actual BLE devices.