Koji AsakawaShinjiro HaraTetsuo HaradaKeiichiro Hitomi...
a59,050003.1-050003.2页
查看更多>>摘要：This special issue on "Microprocesses and Nanotechnology 2024" of the Japanese Journal of Applied Physics (JJAP) is the collection of selected papers from those presented at the 37th International Microprocesses and Nanotechnology Conference (MNC 2024) held in Kyoto, Japan on November 12 to 15, 2024. The scope of this special issue is listed below. Nanotechnology Nanomaterials Nanodevices Nano/micro-fabrication This special issue also contains state-of-the-art lithography, biotechnology, MEMS, and atomic- layer processes. The readers will find the latest achievements of fundamental studies and useful information of industrial applications in nanotechnology research.
查看更多>>摘要：Nanotube (NT) stamping has the advantage of delivering substances to a large number of cells in a shorter time. However, because it was controlled manually, the results varied depending on the individual performing the procedure. Here we propose an automated NT stamping system that enhances the accuracy and reproducibility of delivering liquid substances into cells by combining stepper motor control and image processing with a conventional inverted microscope. The automated system inserts NTs into adherent cells by sequential two-step focusing of the objective lens on the target cells and the NT membrane. We show that the automated system achieves submicron precision in controlling the vertical position of the NTs relative to the adherent cells by the two-step focusing while maintaining a high delivery rate of 72% and high cell viability of more than 90%. The target substances can be delivered into the nuclei of HeLa cells preferentially by our stamping system.
查看更多>>摘要：In this study, we obtained the electrical performance of concentrator photovoltaics (CPV) using InGaP/GaAs/Ge triple-junction solar cells before and after high-energy particle irradiation to examine the effects of solar concentration on radiation tolerance. The conversion efficiency before radiation exposure increased in proportion to the received solar irradiance mainly because of the solar concentration effect of the open-circuit voltage (V_(oc)). Additionally, our experimental results revealed that the solar concentration effect of V_(oc) was enhanced after radiation exposure, which mitigated V_(oc) degradation. To investigate the solar concentration effect on V_(oc) in detail, the recombination current dependencies of the external luminescence efficiency (hext ) of InGaP and GaAs single-junction (1J) cells were measured before and after radiation exposure. It was found that the η_(ext) of InGaP 1J cells after radiation exposure increased with increasing recombination current, which is considered to suppress the degradation of the V_(oc) of the CPV. These findings demonstrate the significant advantages of CPV for space applications.
查看更多>>摘要：We are pleased to present a special issue on Low Temperature Bonding for 3D Integration (LTB- 3D) 2024 of the Japanese Journal of Applied Physics (JJAP). Low temperature bonding is one of the key technologies for electronics device 3D integration as high-performance computing, photonics, power electronics, MEMS, and so on. This special issue is a collection of papers in the field of low temperature bonding, including its science, metrology, and application, as above, based on the presentations at the 2024 8th International Workshop on Low Temperature Bonding for 3D Integration (LTB-3D 2024). The scope of this special issue is listed below.
查看更多>>摘要：Bremsstrahlung, generated when beta rays from carbon-14 interact with materials, offers a non-invasive method for radioactivity measurement in plants. However, because low-energy bremsstrahlung is attenuated by absorbers, attenuation correction is required. This study proposed an attenuation correction method that estimates absorber thickness by analyzing the count ratio in low- and high-energy regions of the spectra. Simulations and experiments were conducted using a germanium detector and soda-lime glass plates as absorbers. Experimental data revealed low-energy background components not observed in simulations, which were successfully estimated and subtracted using a Gaussian approximation. After background subtraction, experimental results aligned well with simulation data, demonstrating a linear relationship between the count ratio and absorber thickness. After applying the attenuation correction, the radioactivity became nearly constant for all glass thicknesses. This approach provides a foundation for non-invasive carbon-14 quantification and has potential applications in radiotracer studies on photosynthetic products in plants.
查看更多>>摘要：To realize a high threshold power transistor on a GaN chip alone, we have developed a GaN-based HEMT featuring AlGaN/p-GaN stacked gate layers and oxidized Ni gate electrodes. Experimental results show the threshold voltage increases with the aluminium composition ratio of the AlGaN gate layer, reaching 3.5 V at 0.20 Al ratio. Additionally, samples with more strongly oxidized Ni gates exhibited an even higher threshold voltage of 5.2 V and very low gate current during on-state. These results suggest that the AlGaN gate layer and oxidized Ni gate play a crucial role for high threshold voltage and low gate current.
查看更多>>摘要：Nanorheological atomic force microscopy (AFM) enables us to measure nano-scale frequency-dependent dynamic moduli by oscillating the cantilever with a wide range of frequencies. However, the storage and loss moduli converted from dynamic stiffness obtained by nanorheological AFM with the contact area calculated by Johnson-Kendall-Roberts (JKR) contact mechanics, which is for elastic bodies with adhesion, exhibit difference compared to those by macroscopic dynamic mechanical analysis due to the different contact areas depending on frequencies. Herein, we modified one of the viscoelastic contact mechanics considering the extent of the relaxation of the bulk deformation, which was disregarded in the original theory, to improve the quantitative accuracy of the contact area. The modification was verified by several experiments. By implementing the theory, we successfully quantified frequency-dependent contact areas, and the nano-scale dynamic moduli by nanorheological AFM showed a better agreement with the macroscopic moduli.
查看更多>>摘要：The resonance properties of A_0- and A_1-mode Lamb waves and SH_1 mode plate waves in a LiNbO_3 (LN) thin plate bonded to a support substrate with periodic voids were simulated using the finite element method. Resonance properties similar to those of the plate waves were obtained by partially bonding the LN thin plate, and the main displacement nodes of the plate waves appeared on the support substrate. For the A_1-mode Lamb wave on 123°YX-LN/4H-SiC with LN thickness h = 0.15λ (where λ is the wavelength) and void width w to pitch p ratio (w/p) = 0.7, a resonance property with a fractional bandwidth (FBW) of 9.3% was obtained at a phase velocity of 15880 m s~(-1) . For the A_0-mode Lamb wave on 141°YX-LN/ glass with h = 0.28λ and w/p = 0.7, a resonance property with FBW of 4.0% was obtained at a phase velocity of 2690 m s~(-1) .
查看更多>>摘要：In this study, the effect of hydrogen radical (HR) treatment on Si/SiO_2 multilayer (ML) films was investigated, focusing on the reduction of silicon dangling bond (Si-DB) defects and their impact on electrical properties. Electron spin resonance analysis revealed that HR treatment effectively reduced the density of Si-DB defects in Si/SiO_2 ML films. Electrical measurements demonstrated enhanced dark conductivity and reduced activation energy of carriers following HR treatment. These changes were attributed to the reduction in Si-DB defects. Furthermore, the photo- sensitivity of the HR-treated films improved, suggesting that HR treatment is a promising technique for defect reduction and performance enhancement of the solar cells with Si/SiO_2 ML absorbers.
Vu Thi HaVuong Van CuongTakamichi MiyazakiShin-Ichiro Kuroki...
a39,056503.1-056503.9页
查看更多>>摘要：In this study, the thermal stability of Ni/Ti and Ni/Ti/Nb ohmic contact on p-type 4H-SiC were investigated for 100 h at 400 ℃ in N_2 environment. The results demonstrated that lower contact resistance and higher thermal stability could be achieved with the Ni/Ti/Nb candidate. After 100 h aging, the specific contact resistance of the Ni/Ti/Nb sample slightly increased from 2.56 × 10~(-3) to 3.04 × 10~(-3) Ω cm~2 . X-ray diffraction results showed that Ni_2Si, Ti_3SiC_2 and Nb_6C_5 compounds contributed to low contact resistance and high-temperature reliability. By adding Nb, the surface of the Ni/Ti/Nb/4H-SiC ohmic contact becomes smoother than that of the Ni/Ti/4H-SiC ohmic contact. The metal/4H-SiC interface of the ohmic contacts was observed after 100 h aging by using TEM measurement. For the Ni/Ti/Nb sample, the excess carbon atoms were collected by the formation of Nb-C compounds and then increased high temperature reliability and reduced contact resistivity.
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