An all-transparent photodetector was fabricated by structuring Cu₂O/ZnO/AZO/ITO on a glass substrate. The visible-range transmittance was as high as 80%, which ensures clear vision forhuman eyes. High-transparency metal conductive oxides (p-type Cu₂O and n-type ZnO) were appliedto form the transparent p/n junction. The functional AZO layer was adopted to improve the transparent photodetector performance between the ZnO and ITO, improving the photoresponses because of its electrical conductivity. To clarify the AZO functionality, a comparator device was prepared without the AZO layer in the formation of Cu₂O/ZnO/ITO/Glass. The Cu₂O/ZnO/AZO/ITO device provided a rectifying ratio of 113.46, significantly better than the 9.44 of the Cu₂O/ZnO/ITO device. In addition, the Cu₂O/ZnO/AZO/ITO device`s photoresponses at short wavelengths were better than those of the comparator. The functioning AZO layer provides ahigh-performing transparent Cu oxide photodetector and may suggest a route for the design of efficient photoelectric devices.

In this work, static characteristics of 4H-SiC SJ-ACCUFETs were obtained by adjusting the p-pillar region. The structure of this SJ-ACCUFET was designed by using a two-dimensional simulator. The static characteristics of SJ-ACCUFET, such as the breakdown voltages, on-resistance, and figure of merits, were obtained by varying the p-pillar doping concentration from 1×10¹⁵ cm^-3 to 5×10¹⁶ cm^-3 and the thickness from 0 μm to 9 μm. The doping concentration and the thickness of p-pillar region are closely related to the break down voltage and on-resistance and threshold voltages. Hence a silicon carbide SJ-ACCUFET structure with highly intensified breakdown voltages and low on-resistances with good figure of merits can be achieved by optimizing the p-pillar thickness and doping concentration.

Zinc sulphide (ZnS) nanoparticles were fabricated by hydrothermal synthesis at 180℃ for 12 h. Two kinds of ZnS powder (hydrothermal synthesized ZnS and commercial ZnS) were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) for phase and microstructure, respectively. The XRD patterns showed that all ZnS nanoparticles have a sphalerite (cubic) structure. The nanoparticles of two different ZnS powders were sintered by spark plasma sintering. The sintered ZnS were analyzed by XRD, SEM, and FT-IR. We found that the transmittance of the infrared region is highly dependent on the density and crystal structure of sintered ZnS and the purity of the starting ZnS powder.

We investigated the phase evolution, microstructure, and microwave dielectric properties of Na- and Zr-doped Ba(Mg_0.5W_0.5)O₃ [i.e., (Ba_1-2xNa_2x)(Mg_0.5-xZr_xW_0.5)O₃] ceramics. BaWO₄ as a secondary phase was observed in all compositions, and it increased as the dopant concentration increased. All specimens revealed a dense microstructure. For the composition of x=0.01, polyhedral grains were observed. As the dopant concentration increased, the densification and the grain growth were promoted by a liquid phase. The quality factor(Q×f₀) decreased remarkably, whereas the dielectric constant (ε_r) tended to decrease as the dopant concentration increased. The dielectric constant, quality factor, and temperature coefficient of the resonant frequency of the composition of x=0.01 sintered at 1,700℃ for 1 h were 18.6, 216,275 GHz, and -22.0 ppm/℃, respectively.

In this paper, we investigated the effect of Co content on the microstructural and electrical properties of Ni_0.79Mn_2.21-xCo_xO₄ (x=0 to 0.25) specimens. Solid-state reaction was used to prepare the bulk specimens. XRD (X-ray diffraction) patterns showed that all compositions had a cubic spinel phase. As a result of the microstructural properties, FE-SEM(field-emission scanning electron microscopy) analysis showed a dense structure, and the mean grain size increased from 5.24 μm to 7.33 μm with an increase of Co content from x=0 to 0.25. All specimens exhibited the typical NTC thermistor characteristics as the electrical resistance exponentially decreased with increasing temperature. The resistivity and the B-value of Ni_0.79Mn_1.96Co_0.25O₄ were 2959 Ω·cm and 3719, respectively.

In this paper, we introduce an electrocardiogram (ECG) system designed to solve problems caused by wetgels and motion artifacts in measuring active movement. The system is called a dry-contact ECG and was designed by considering impedance matching between skin and electrode as well as the frictional electricity between electrode and clothes. In order to create the system, we measured impedance on the skin-electrode interface, and the result was applied to the electronic circuit scheme. Moreover, we added an electrode on the back of the measurement electrode to make a flow path to ground the electrical noise. The final ECG circuit and novel electrode were used to detect real human cardiac signals from a subject who was tested while standing still and walking. The signals obtained from the two activities were nicely shaped, without any motion artifact noise. We took electrode size into account in this study because the impedance depended on the area of the electrode. An electrode of 50 mm diameter showed the best curve for the ECG signal without any electrical noise.

ZnO thin films were deposited by RF magnetron sputtering and then diffused by using an As source in the ampouletube. Also, the ZnO p-n homojunction was made by using As-doped ZnO thin films, and its properties were analyzed. After the As doping, the surface roughness increased, the crystal quality deteriorated, and the full width at half maximum was increased. The As-doped ZnO thin films showed typical p-type properties, and their resistivity was as low as 2.19×10^-3 Ωcm, probably because of the in-diffusion from an external As source and out-diffusion from the GaAs substrate. Also, the ZnO p-n junction displayed the typical rectification properties of a p-n junction. Therefore, the As diffusion method is effective for obtaining ZnO films with p-type properties.

In this paper, we prepared a metal alloy resistor with stable thermal electro motive force (thermal EMF) as well as a low temperature coefficient of resistance (TCR) by adjusting the manganese proportion from 3 to 12 wt% in the Cu-Mn-Ni alloy. Composition of the fabricated metal alloy was investigated using energy dispersive X-ray (EDX) analysis. The TCR of each sample was measured as 44.56, 40.54, 35.60, and 31.56 ppm for Cu-3Mn-2Ni, Cu-5Mn-2Ni, Cu-10Mn-2Ni, and Cu-12Mn-2Ni, respectively. All the resistor samples were available for the F grade (±1% of the allowable error of resistance) high-precision resistor. All the samples satisfied the baseline of high thermal EMF (under 3 mV at 60℃); however, Cu-3Mn-2Ni and Cu-5Mn-2Ni satisfied the baseline of low thermal EMF (under 0.3 mV at 25℃). We were thus able to design and fabricate the metal alloy resistor of Cu-3Mn-2Ni and Cu-5Mn-2Ni to have low TCR and stable thermal EMF at the same time.

A railway track generates severe levels of vibrations. In order to reduce these vibrations and to provide structural stability, various rail pads, mats, etc., are used for vibration protection. In this study, a specially designed rail pad was developed to reduce vibration and to generate electric power simultaneously, that is, by using the vibrations generated by railway cars on the track. The newly developed rail pads were tested to evaluate the characteristics of electric power by investigating the generated voltage and the current levels and patterns. In addition, we proposed an optimal laminated structure and adhesive by comparing the voltage generated by each type of adhesive required for optimal adhesion of the rail pad and the piezoelectric device.

A high-performing all-transparent photodetector was created by configuring a MoO_x/NiO/ZnO/ITO structure on a glass substrate. The ITO bottom layer was applied as a back contact. To achieve the transparent p/n junction, p-type NiO was coated on the n-type ZnO layer. Reactive sputtering was used to spontaneously form the ZnO or NiO layer. In order to improve the transparent photodetector performance, the functional MoO_x window layer was used. Optically, the MoO_x window provided a refractive index layer (n=1.39) lower than that of NiO (n=2), increasing the absorption of the incident light wavelengths (λ_s). Moreover, the MoO_x window can provide a lower sheet resistance to improve the carrier collection for the photoresponses. The MoO_x/NiO/ZnO/ITO device showed significantly better photoresponses of 877.05 (at λ=460 nm), 87.30 (λ=520 nm), and 30.38 (λ=620 nm), compared to 197.28 (λ=460 nm), 51.74 (λ=520 nm) and 25.30 (λ=620 nm) of the NiO/ZnO/ITO device. We demonstrated the high-performing transparent photodetector by using the multifunctional MoO_x window layer.

For comparison to the Li-ion battery, evaluating a thermal battery must consider additional variables. The first one is the temperature difference between the battery and its unit cell. Thermal batteries and their unit cells have a temperature difference that is caused by the thermal battery activation mechanism and its shape. The second variable is the electrochemical reaction steps. Most Li-ion batteries have a constant electrochemical reaction at the electrode, and battery voltage is affected when the concentration of Li ions is changed. However, a thermal battery has several steps in its electrochemical reaction, and each step has a different potential. In this study, we used unit cell discharge tests based on interpolating a 4D lookup table to estimate the performance of a thermal battery. From the test results, we derived an estimation algorithm by interpolating the table, which is queried from specified profile groups. As a result, we found less than a 5 percent difference between estimation and experiment at the 1.3 V cut-off time.

Because silicon thin film solar cells have a high absorption coefficient in visible light, they can absorb 90% of the solar spectrum in a 1-μm-thick layer. Silicon thin film solar cells also have high transparency and are lightweight. Therefore, they can be used for building integrated photovoltaic (BIPV) systems. However, the contact electrode needs to be replaced for fabricating silicon thin film solar cells in BIPV systems, because most of the silicon thin film solar cells use metal electrodes that have a high reflectivity and low transmittance. In this study, we replace the conventional aluminum top electrode with a transparent aluminum-doped zinc oxide (AZO) electrode, the band level of which matches well with that of the intrinsic layer of the silicon thin film solar cell and has high transmittance. We show that the AZO effectively replaces the top metal electrode and the bottom fluorine-doped tin oxide (FTO) substrate without a noticeable degradation of the photovoltaic characteristics.