We experimentally demonstrate frequency conversion based on a spoof-surface plasmon-polariton waveguide and microbridge resonator arrays integrated into the gap of a split-ring resonator array capacitively coupled to the waveguide. Frequency conversion was achieved by mixing the microwave carrier frequency with a modulation frequency of 39.7 MHz. Owing to its compact size and lightweight structure, the microbridge exhibits high-speed operation with a mechanical resonant frequency of 1.66 MHz in air. The mechanical resonant frequency of the microbridge was determined from the sidebands. These findings show how microwave frequency conversion in integrated microwave circuits can enable time-varying metamaterial applications.
The Japan Society of Applied Physics (JSAP) serves as an academic interface between science and engineering and an interactive platform for academia and the industry. JSAP is a "conduit" for the transfer of fundamental concepts to the industry for development and technological applications.
JSAP was established as an official academic society in 1946, and since then, it has been one of the leading academic societies in Japan. The society's interests cover a broad variety of scientific and technological fields, and JSAP continues to explore state-of-the-art and interdisciplinary topics.
To this end, the JSAP holds annual conferences; publishes scientific journals; actively sponsors events, symposia, and festivals related to science education; and compiles information related to state-of-the-art technology for the public.
ISSN: 1347-4065
SUPPORTS OPEN ACCESS
The Japanese Journal of Applied Physics (JJAP) is an international journal for the advancement and dissemination of knowledge in all fields of applied physics.
Median submission to first decision before peer review5 days
Median submission to first decision after peer review27 days
Impact factor1.7
Citescore3.1
- The following article is Open accessMicrowave frequency conversion using a spoof surface plasmon polariton waveguide integrated with split-ring resonators and micro-electromechanical resonator arrays
Minh Van Nguyen et al 2026 Jpn. J. Appl. Phys. 65 197001
View article, Microwave frequency conversion using a spoof surface plasmon polariton waveguide integrated with split-ring resonators and micro-electromechanical resonator arraysPDF, Microwave frequency conversion using a spoof surface plasmon polariton waveguide integrated with split-ring resonators and micro-electromechanical resonator arrays - The following article is Open accessAdvancing solid state reaction science and process engineering through in situ X-ray diffraction
Jacob L. Jones et al 2026 Jpn. J. Appl. Phys. 65 190801
View article, Advancing solid state reaction science and process engineering through in situ X-ray diffractionPDF, Advancing solid state reaction science and process engineering through in situ X-ray diffractionSolid state synthesis of ceramics typically involves heating of well-mixed precursor inorganic oxides, carbonates, hydroxides, etc. at elevated temperatures. In many cases, a unique precursor is used for each metal cation. As ceramic compositions become more complex, using more precursors increases the risk of side reactions that lower final phase purity. Therefore, improving the phase purity requires a fundamental understanding of reaction mechanisms (synthesis science) to better guide process engineering. In situ X-ray diffraction (XRD) achieves this by providing real-time phase identification and dynamic structural information during heat treatment. This Progress Review introduces applications of in situ XRD to study solid state reactions that form leading lead-free ferroelectric ceramics. The results demonstrate new insights into perovskite phase formation and routes to process engineering of more phase pure products. Additional applications reviewed in energy conversion and storage demonstrate the generality of the approach to other systems.
- The following article is Open accessIn-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yoke
Mitsunori Miyamoto et al 2026 Jpn. J. Appl. Phys. 65 20SP01
View article, In-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yokePDF, In-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yokeIn recent years, the switching frequency of power converters has increased significantly with the widespread adoption of wide-bandgap power semiconductors. Conventional sensors, such as current transformers and Rogowski coils, are limited by their size and frequency bandwidth, making accurate current measurement difficult. The optical probe current sensor developed by the authors is effective for high-frequency current measurements due to its compact sensor head and wide bandwidth (DC to 150 MHz). Although this sensor can measure magnetic fields in narrow spaces, measuring wideband current in wide conductors like busbars or copper traces remains challenging due to skin and proximity effects. In this study, we improved the frequency response of the sensor by integrating it with a half-open loop magnetic yoke that homogenizes the magnetic field around the conductor. Finally, we report the in-situ measurement results of the drain current flowing through a SiC-MOSFET during a double-pulse test using the proposed sensor.
- The following article is Open accessVirtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutions
Satoshi Murasugi et al 2026 Jpn. J. Appl. Phys. 65 208003
View article, Virtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutionsPDF, Virtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutionsImpurity doping of semiconductors is an important technique for controlling electronic and optical properties. However, it remains challenging to dope crystalline organic semiconductors, since the difference in molecular shapes and charge distribution between host and guest compounds easily degrade the crystallinity. In this study, we conducted a large-scale virtual screening of guest compounds capable of forming solid solutions with 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10) host crystals. Tetracene was one of the suitable guest molecules found in this study. Tetracene-doped Ph-BTBT-C10 crystalline solid solutions were experimentally validated with the powder X-ray diffraction and photoluminescence spectra. These results demonstrate that our computational screening method is an effective approach for efficiently discovering crystalline organic semiconductor solid solutions.
- The following article is Open accessWire resistance canceling in flexible thermistor arrays with carbon black wires
Yuto Izumino et al 2026 Jpn. J. Appl. Phys. 65 198002
View article, Wire resistance canceling in flexible thermistor arrays with carbon black wiresPDF, Wire resistance canceling in flexible thermistor arrays with carbon black wiresWe fabricated a 4 × 4 passive matrix flexible temperature sensor array using carbon black (CB) wire and developed a wire resistance canceling (WRC) algorithm to compensate for voltage drops and crosstalk stemming from the high resistance of the CB-based wires (approx. 4900 Ω cm−1). The WRC algorithm operates solely through numerical computation without additional hardware; it determines the true conductance of each sensor by solving matrix equations derived from an equivalent circuit via an iterative method, utilizing pre-measured wire resistances and the measured current. For temperature measurements between 40 and 100 °C, the root-mean-square error decreased from 10.55 °C–56.76 °C (pre-WRC) to 3.12 °C–6.07 °C (post-WRC), representing 64.6%–89.3% improvements. This approach provides an effective compensation strategy for passive matrix sensor arrays with high-resistance printed wire, facilitating the development of low-cost, large-area flexible sensors.
- Material science and device physics in SiC technology for high-voltage power devices
Tsunenobu Kimoto 2015 Jpn. J. Appl. Phys. 54 040103
View article, Material science and device physics in SiC technology for high-voltage power devicesPDF, Material science and device physics in SiC technology for high-voltage power devicesPower semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600–1700 V) SiC Schottky barrier diodes (SBDs) and power metal–oxide–semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.
- The following article is Open accessSingle-molecule detection and quantification of O6-Methylguanine using electrical tunneling fingerprints
Shinya Sakano et al 2026 Jpn. J. Appl. Phys. 65 19SP05
View article, Single-molecule detection and quantification of O6-Methylguanine using electrical tunneling fingerprintsPDF, Single-molecule detection and quantification of O6-Methylguanine using electrical tunneling fingerprintsChemical modifications of nucleobases regulate genomic stability and therapeutic response, yet identifying individual modified bases remains challenging because subtle structural changes often produce similar electronic properties. Here, we report the label-free single-molecule electrical identification and quantification of O6-methylguanine (O6-MeG) using tunneling-current measurements with mechanically controllable break-junction electrodes. Density functional theory calculations predicted that O6-MeG and guanine should be difficult to distinguish by conductance alone because of their similar frontier orbital energies. Consistently, both molecules exhibited nearly identical tunneling-current amplitudes. However, transient tunneling-current signals contained reproducible dynamic fingerprints that enabled reliable discrimination of O6-MeG from guanine, 8-oxoG, and adenine. Predefined O6-MeG/guanine mixtures were also quantified accurately. These results demonstrate that transient tunneling-current fingerprints provide chemically meaningful information beyond static conductance, offering a promising approach for the label-free electrical analysis of DNA damage.
- The following article is Open accessDevelopment of an ultra-high-dose-rate irradiation field using KURNS-LINAC
Kaito Fuchigami et al 2026 Jpn. J. Appl. Phys. 65 196502
View article, Development of an ultra-high-dose-rate irradiation field using KURNS-LINACPDF, Development of an ultra-high-dose-rate irradiation field using KURNS-LINACUltra-high-dose-rate (UHDR) radiotherapy is expanding across modalities, but its mechanisms and optimal irradiation conditions remain unclear. This study aimed to establish a UHDR electron irradiation field using KURNS-LINAC to support research to elucidate the underlying mechanisms. The irradiation field was characterized through a comprehensive dosimetric evaluation using graphite blocks, radiochromic films, glass dosimeters, and Monte Carlo simulations. Single-shot irradiation experiments were conducted using 8 MeV electrons, and the dose rate at different distances from the beam port was evaluated. The results showed a monotonic decrease in the dose rate with increasing distance. The maximum pulse dose rate reached 8.07 × 107 Gy s−1, satisfying the conditions required for the FLASH effect. The two-dimensional dose distributions revealed beam broadening and a gradual reduction in the steep dose gradient with increasing distance due to air scattering. These findings demonstrate that the KURNS-LINAC can provide a flexible platform for UHDR irradiation.
- The following article is Open accessNumerical simulation of electron mobility in ultra-thin silicon nanosheets with out-of-plane phonons
Hikaru Horii et al 2026 Jpn. J. Appl. Phys. 65 181002
View article, Numerical simulation of electron mobility in ultra-thin silicon nanosheets with out-of-plane phononsPDF, Numerical simulation of electron mobility in ultra-thin silicon nanosheets with out-of-plane phononsThe phonon-limited electron mobility
of Si nanosheets, which are confined in the [001] direction with a thickness of less than 2 nm, is investigated in the presence of out-of-plane acoustic (ZA) phonons. Density functional theory, together with the Boltzmann transport theory within the relaxation-time approximation, is used to estimate the contribution of the ZA phonons. The results show that in the case of low temperature or thin thickness, exhibits a distinctive decrease as the electron density decreases even in the nondegenerate region. This low- mobility reduction originates from the strong interaction with ZA phonons toward smaller . At room temperature, the low- mobility reduction remains for nm but disappears for nm. - The following article is Open accessModeling of third-order intermodulation distortion generation by modulated signals in a surface acoustic wave device exhibiting an anomalous power law
Viateur Iragire et al 2026 Jpn. J. Appl. Phys. 65 196501
View article, Modeling of third-order intermodulation distortion generation by modulated signals in a surface acoustic wave device exhibiting an anomalous power lawPDF, Modeling of third-order intermodulation distortion generation by modulated signals in a surface acoustic wave device exhibiting an anomalous power lawThis paper studies third-order intermodulation distortion (IMD3) generation by modulated signals in surface acoustic wave (SAW) devices exhibiting an anomalous power law. First, theoretical discussions are given on IMD3 generation when three signals with frequency fi and power Pi (i= 1, 2, 3) are given simultaneously to the relevant system. It is shown that the variation of IMD3 with a frequency of 2f1 – f2 is mostly governed by P2/P1 and not much changed by P3. The proportional constant increases gradually with P3/P1. Furthermore, the proportional constant variations are expressed as simple polynomials of P3/P1. Next, the discussion is extended to IMD3 generation by mixture of orthogonal frequency division multiplexing (OFDM) and continuous wave signals. An OFDM signal is synthesized and applied to a band 8 temperature-compensated SAW duplexer exhibiting the anomalous power law. Measured results agree well with the theoretical model described above. Surprisingly, these agreements hold even when the jammer power is weak. Namely, IMD3 behavior is governed by the power ratio of the jammer with each subcarrier instead of the total signal power.
- Dynamic RON performance of ultra-wide bandgap AlGaN-channel HEMTs up to 1 kV off-state blocking voltage
Aditya Dev Varma et al 2026 Jpn. J. Appl. Phys. 65 210901
View article, Dynamic RON performance of ultra-wide bandgap AlGaN-channel HEMTs up to 1 kV off-state blocking voltagePDF, Dynamic RON performance of ultra-wide bandgap AlGaN-channel HEMTs up to 1 kV off-state blocking voltageUltra-wide bandgap Al-rich AlGaN high-electron-mobility transistors (HEMTs) are compelling for next-generation power electronics due to their high critical electric fields. However, the performance of nitride HEMTs is limited by degradation of RON during switching operation. To date, the switching performance of AlGaN-channel HEMTs has not been evaluated under high-voltage (> 600 V) off-state bias. We demonstrate dynamic performance of AlGaN-channel HEMTs under off-state blocking voltages up to 1 kV, showing RON degradation of 1.5×/650 V and 6.5×/1000 V with a single-field-plate structure. These results highlight initial progress and challenges towards engineering degradation-free AlGaN-channel kV lateral transistors.
- Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loading
Shinya Ohta et al 2026 Jpn. J. Appl. Phys. 65 20SP08
View article, Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loadingPDF, Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loadingWe investigated the electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loading. A 26-layer cell was fabricated using corona-charged FEP/porous-PTFE/FEP electret films. The corona-treated films exhibited a surface potential difference of approximately −1.9 kV. Under quasi-static compressive loading at 2.0 N cm−2, generated charges of approximately 1.0–1.7 µC were obtained, depending on the sample. Under finger tapping, the apparent average force and stress level were estimated to be approximately 3–6 N and 1.5–6 N cm−2, respectively. Under continuous finger tapping at an average frequency of 5.4 Hz, the measured average output power was 231 µW. The harvested energy was rectified and stored, and the stored energy was used for BLE advertising and connection establishment with a previously paired receiving device. These results demonstrate the feasibility of applying multilayer porous fluoropolymer electret cells to energy-harvesting systems driven by relatively small human mechanical inputs.
- Optimizing weight ratio of phytochemical curcumin as acceptor in organic photodiodes using different donor materials
Shuzo Miyamoto et al 2026 Jpn. J. Appl. Phys. 65 20SP07
View article, Optimizing weight ratio of phytochemical curcumin as acceptor in organic photodiodes using different donor materialsPDF, Optimizing weight ratio of phytochemical curcumin as acceptor in organic photodiodes using different donor materialsOrganic photodiodes employing curcumin, an environmentally friendly and low-cost phytochemical polyphenol, are fabricated and evaluated for an acceptor material in the photoactive layer. Two different donor host materials are investigated by varying the curcumin ratio. For one donor host system, optimizing the curcumin weight ratio achieves high specific detectivity, and introducing a MoO3 electron extraction layer enhances the photocurrent at low reverse bias. By employing the other donor host, which exhibits minimal absorption band overlap with curcumin, we demonstrate that curcumin directly contributes to photocurrent generation. Furthermore, the light-intensity dependence of the photocurrent in the devices using the latter host suggests a photocurrent multiplication property. These results demonstrate that sustainable phytochemicals like curcumin can function as effective semiconducting materials in green organic electronic devices.
- Characterization and magnetic properties of Ni–Pt alloy nanowires fabricated by electrodeposition and nanoporous templates
Yusuke Oda et al 2026 Jpn. J. Appl. Phys. 65 20SP06
View article, Characterization and magnetic properties of Ni–Pt alloy nanowires fabricated by electrodeposition and nanoporous templatesPDF, Characterization and magnetic properties of Ni–Pt alloy nanowires fabricated by electrodeposition and nanoporous templatesNi–Pt alloy (NiXPt100−X) nanowires were fabricated using a porous nano-template and an electrodeposition method, and their structural, magnetic, and electrical transport properties were investigated. By varying the Ni/Pt ion concentration ratio in the electrolyte and the electrodeposition potential, Ni–Pt alloy nanowires with compositions of 22 ⩽ X ⩽ 80 were successfully fabricated. Structural characterization revealed that all fabricated nanowires exhibited a polycrystalline face-centered cubic structure. The lattice constant decreased with increasing X, confirming the formation of Ni–Pt alloys. Magnetic measurements at room temperature demonstrated the emergence of ferromagnetism for X ⩾ 70, and the Ni79Pt21 nanowire exhibited a saturation magnetization of 140 emu cm−3. Furthermore, anisotropic magnetoresistance measurements performed on a single Ni79Pt21 nanowire yielded a magnetoresistance ratio of 0.080 ± 0.002%. These results provide useful insights into the material design of Ni–Pt alloy nanowires for the magnetic memory applications.
- The effect of magnetization structures inside particles on the permeability of soft magnetic composites revealed by micromagnetic simulations
Zhenyu Long et al 2026 Jpn. J. Appl. Phys. 65 203001
View article, The effect of magnetization structures inside particles on the permeability of soft magnetic composites revealed by micromagnetic simulationsPDF, The effect of magnetization structures inside particles on the permeability of soft magnetic composites revealed by micromagnetic simulationsMicromagnetic simulations were performed to clarify how magnetization structures inside particles affect the permeability of soft magnetic composites. Quasi-two-dimensional simulation models were designed with the volume fraction of
-Fe particles ranging from to . Initial magnetization curves were calculated to estimate the initial and maximum permeabilities. The permeabilities were compared with the Ollendorff model as an effective medium theory baseline. The initial permeability increased almost linearly with the volume fraction and was reasonably described by the Ollendorff model. In contrast, the maximum permeability increased rapidly in the high-volume-fraction region. This rapid increase was not reproduced by the Ollendorff model. The analysis showed that this discrepancy was attributed to changes in magnetic vortex structures inside particles. These results indicate that the initial permeability is mainly governed by the volume fraction, whereas the maximum permeability in dense models is strongly affected by the magnetization structures inside particles.
- The following article is Open accessAdvancing solid state reaction science and process engineering through in situ X-ray diffraction
Jacob L. Jones et al 2026 Jpn. J. Appl. Phys. 65 190801
View article, Advancing solid state reaction science and process engineering through in situ X-ray diffractionPDF, Advancing solid state reaction science and process engineering through in situ X-ray diffractionSolid state synthesis of ceramics typically involves heating of well-mixed precursor inorganic oxides, carbonates, hydroxides, etc. at elevated temperatures. In many cases, a unique precursor is used for each metal cation. As ceramic compositions become more complex, using more precursors increases the risk of side reactions that lower final phase purity. Therefore, improving the phase purity requires a fundamental understanding of reaction mechanisms (synthesis science) to better guide process engineering. In situ X-ray diffraction (XRD) achieves this by providing real-time phase identification and dynamic structural information during heat treatment. This Progress Review introduces applications of in situ XRD to study solid state reactions that form leading lead-free ferroelectric ceramics. The results demonstrate new insights into perovskite phase formation and routes to process engineering of more phase pure products. Additional applications reviewed in energy conversion and storage demonstrate the generality of the approach to other systems.
- Understanding plasma etching processes through surface reaction models
Masaru Izawa 2026 Jpn. J. Appl. Phys. 65 160101
View article, Understanding plasma etching processes through surface reaction modelsPDF, Understanding plasma etching processes through surface reaction modelsAs large-scale integration (LSI) devices have shrunk, plasma etching has encountered challenges such as microloading and critical dimension (CD) shift. To clarify the underlying mechanisms, we developed an etching-rate model based on precursor-mediated adsorption with surface diffusion. Applied to silicon (Si) etching, the model reproduced reactant-limited behavior at low pressure through efficient utilization of incident chlorine (Cl). When extended to aluminum (Al) etching, the model incorporated adsorption of etching by-products, showing that microloading was governed by etchant flux limitation and Al etching by-product adsorption at low pressure, whereas ion shadowing dominated at high pressure, indicating an optimal pressure near 2 Pa. CD shift was formulated based on the balance among deposition of photoresist by-products, ion sputtering, and reactions with Cl and O radicals at the sidewall. The model reproduced differences between isolated and dense patterns and center-to-edge variations, providing mechanistic insights and practical guidance for plasma etching.
- Effect of neutron irradiation on the synthesis of nano-layered diamond from highly oriented pyrolytic graphite (HOPG) under high-pressure and high-temperature treatment
Shin-ichi Honda et al 2026 Jpn. J. Appl. Phys. 65 155002
View article, Effect of neutron irradiation on the synthesis of nano-layered diamond from highly oriented pyrolytic graphite (HOPG) under high-pressure and high-temperature treatmentPDF, Effect of neutron irradiation on the synthesis of nano-layered diamond from highly oriented pyrolytic graphite (HOPG) under high-pressure and high-temperature treatmentUsing neutron-irradiated highly oriented pyrolytic graphite (n-HOPG) as a starting material, we have synthesized nano-layered diamonds for the first time by high-pressure and high-temperature treatment at 15 GPa and 2070 °C. Furthermore, analysis of the in situ angle-dispersive X-ray diffraction patterns of n-irradiated and unirradiated HOPGs showed cubic diamond (cDIA) formation was not observed for n-HOPG below approximately 1400 °C, but was for unirradiated HOPG at approximately 1000 °C. In contrast, transmission electron microscopy observation of the recovered specimens revealed that nano-layered cDIAs oriented in the [111] direction were formed in both n-irradiated and unirradiated HOPGs. Still the thickness of the individual nano-layered cDIAs was larger in n-HOPG than in unirradiated HOPG. These results were discussed in terms of the recovery of irradiation-induced defects with increasing temperature under high pressure in n-HOPG and the nucleation and growth of diamond.
- Degradation mechanisms for copper interconnects and approaches to increasing reliability
Kazuyoshi Ueno and Fumihiro Inoue 2026 Jpn. J. Appl. Phys. 65 150801
View article, Degradation mechanisms for copper interconnects and approaches to increasing reliabilityPDF, Degradation mechanisms for copper interconnects and approaches to increasing reliabilityThis paper reviews the failure mechanisms for the copper (Cu) interconnects used in integrated circuits for the past 30 years, including electromigration (EM), stress-induced voiding (SIV) and time-dependent dielectric breakdown (TDDB), together with countermeasures, focusing on the authors’ own research. The EM phenomenon generates voids based on the movement of Cu atoms driven by electric currents. This mechanism can be mitigated using direct contact via structures and cobalt caps. Voids can also be induced by SIV as a result of the migration of Cu atoms in response to stress gradients. This effect can be reduced by decreasing the interconnect width and by lowering the stress throughout the insulating film structure. TDDB occurs as a consequence of Cu diffusion in insulating films and interfaces in response to an electric field, meaning that it is important to modify chemical/mechanical polishing interfaces that may otherwise provide diffusion paths. This paper also addresses future prospects and challenges related to interconnect reliability and discusses recent trends with regard to nano-interconnects, backside power delivery networks and three dimensional integration.
- Analytical approaches to radiation impedance and structural vibration in underwater acoustic transducer design
Moojoon Kim 2026 Jpn. J. Appl. Phys. 65 140801
View article, Analytical approaches to radiation impedance and structural vibration in underwater acoustic transducer designPDF, Analytical approaches to radiation impedance and structural vibration in underwater acoustic transducer designThis paper reviews analytical solution methods for key parameters governing sensor characteristics in underwater acoustic system design that are often expressed in complex forms. In transducer modeling, parameters related to radiation impedance, structural vibration, and boundary-induced acoustic interactions are essential for performance prediction, yet their complexity often limits physical insight and efficient design. Focusing on representative cases, the review examines analytical approaches for (i) evaluating the radiation impedance of finite vibrating surfaces, (ii) describing changes in self- and mutual-radiation impedance caused by reflected waves from surrounding structures, and (iii) analyzing the vibration behavior of compliant elements such as barrel-shaped shells in flextensional transducers. Rather than proposing new theories, the paper emphasizes how existing analytical techniques can be systematically organized to obtain physically meaningful solutions. By clarifying solution strategies and their physical implications, this review provides practical guidance for impedance-based modeling of underwater acoustic sensors, particularly for low-frequency and broadband applications.
- Enhanced Photoresponse of a Solution-Gated Organic Phototransistor Using a Plasmonic Organic Solar-Cell Gate
Tianshuo et al
View accepted manuscript, Enhanced Photoresponse of a Solution-Gated Organic Phototransistor Using a Plasmonic Organic Solar-Cell GatePDF, Enhanced Photoresponse of a Solution-Gated Organic Phototransistor Using a Plasmonic Organic Solar-Cell GateA solution‑gated organic phototransistor (SGOPT) was developed by integrating a plasmonic P3HT:PCBM organic solar cell (OSC) gate with a P3HT/graphene oxide (GO) field‑effect transistor through a phosphate‑buffered saline electrolyte. The OSC converts incident light into an open‑circuit photovoltage delivered to the transistor channel via the electrolyte/GO interface, and its grating structure enables propagating surface plasmon (PSP) excitation. P‑polarized reflectance from the ITO side exhibited angle‑dependent modulation over 500–700 nm, while FDTD calculations revealed an RP/RS minimum near 627 nm and p‑selective interfacial field localization at 620 nm, consistent with PSP-assisted coupling. Measurement states distinguished direct FET photoresponse, OSC‑only photogating, and simultaneous OSC/FET illumination, the latter producing the largest drain‑current change. P‑polarized illumination generated a stronger response than s‑polarized illumination, and 620‑nm light produced a larger response than 500‑nm light. These optical and electrical trends are consistent with a PSP‑assisted contribution.
- The following article is Open accessEfficient liquid exfoliation and dispersion formation of alkyl-terminated germananes
Azumi et al
View accepted manuscript, Efficient liquid exfoliation and dispersion formation of alkyl-terminated germananesPDF, Efficient liquid exfoliation and dispersion formation of alkyl-terminated germananesWe report a simple preparation method for dispersions of alkyl-terminated germananes, GeCnH2n+1 (n = 1, 3, 6, 8, and 12), in halogenated solvents. The dispersion efficiency and suitable solvent were strongly dependent on the terminal alkyl-chain length; with appropriate combinations of alkyl-chain length and solvent identity, liquid exfoliation was achieved not only by ultrasonication but even by simple mechanical stirring at room temperature. Sufficiently long alkyl chains facilitated exfoliation by expanding the interlayer spacing; however, the dispersion concentration did not simply increase monotonically with alkyl-chain length. These results indicate that the behavior of dispersions is governed by a balance among interlayer expansion, solvent affinity for the alkyl-chain region, and kinetic processes such as reaggregation and sedimentation. This mild and practical method may provide a useful route toward solution processing of alkyl-terminated germananes.
- Laser-intensity and irradiation-time dependence of blue- and red-phase polydiacetylene formation during femtosecond multiphoton polymerization
Okada et al
View accepted manuscript, Laser-intensity and irradiation-time dependence of blue- and red-phase polydiacetylene formation during femtosecond multiphoton polymerizationPDF, Laser-intensity and irradiation-time dependence of blue- and red-phase polydiacetylene formation during femtosecond multiphoton polymerizationWe investigated the effects of laser power density and irradiation time on the formation of blue- and red-phase polydiacetylene (PDA) by femtosecond multiphoton polymerization of 10,12-tricosadiynoic acid (TDA) thin films. By monitoring the absorbance changes at 638 and 514 nm, the temporal evolution of blue- and red-phase PDA during photopolymerization was evaluated separately. An intensity-time phase diagram constructed from these data revealed a trade-off between the degree of polymerization and blue-phase retention. Within the evaluated range, the condition yielding the maximum extent of polymerization while maintaining a blue-phase fraction of at least 80% was estimated to be a laser power density of 1.2 W/cm² and an irradiation time of 0.30 s. Translating the substrate at 0.54 cm/s reduced the effective irradiation time at each position and yielded a blue-phase fraction of 60.3% at 1.6 W/cm². Increasing the laser power density to 3.2 W/cm² decreased the blue-phase fraction to 47.3% but increased the deconvoluted blue-phase peak absorbance by a factor of 2.19. These results suggest that short-duration irradiation at a sufficiently high laser power density can promote the formation of blue-phase PDA while limiting its conversion to the red-phase.
- Naphthobisthiadiazole-based nonfullerene acceptors for organic solar cells: molecular design, structure–property relationships, and synthetic perspectives
Chatterjee et al
View accepted manuscript, Naphthobisthiadiazole-based nonfullerene acceptors for organic solar cells: molecular design, structure–property relationships, and synthetic perspectivesPDF, Naphthobisthiadiazole-based nonfullerene acceptors for organic solar cells: molecular design, structure–property relationships, and synthetic perspectivesThe development of nonfullerene acceptors (NFAs) based on -conjugated molecules has driven recent advances in organic solar cells (OSCs), with electron-deficient units playing a key role in their molecular design. This review highlights naphthobisthiadiazole (NTz)-based NFAs and their structure–property relationships, focusing on how fluorination, substitution, and π-extension regulate electronic structures, optical properties, blend morphology, and photovoltaic performance. Particular attention is paid to NTz-based NFAs combined with poly(3-hexylthiophene) (P3HT), a practical donor polymer with favorable cost and processability. This combination has enabled green-light wavelength-selective OSCs (GLWS-OSCs) that selectively convert green light into electricity while transmitting blue and red light for plant photosynthesis, providing a promising approach to greenhouse agrivoltaics. Finally, the synthetic complexity of NTz-based materials and the potential of direct C–H functionalization as a concise and scalable synthetic strategy are discussed.
- Hot spot suppression in cell-level TCT-interconnected modules and verification by circuit simulation
Shimizu et al
View accepted manuscript, Hot spot suppression in cell-level TCT-interconnected modules and verification by circuit simulationPDF, Hot spot suppression in cell-level TCT-interconnected modules and verification by circuit simulationThe output performance of photovoltaic modules with cell-level Total Cross-Tied (TCT) interconnection was compared with that of conventional Series-Parallel (SP) modules under partial shading conditions. In the SP module, partial shading reduced the short-circuit current, resulting in a significant decrease in output power. In addition, hot spots were observed in several cells. Although the TCT module exhibited a similar reduction in short-circuit current, the output power loss was smaller because of an improved fill factor (FF). The experimental results demonstrate that TCT cell interconnection effectively suppresses hot-spot formation under partial shading conditions. Circuit simulations reproduced the experimental results and enabled prediction of cell temperature rise under partial shading conditions.
Trending on Altmetric
- The following article is Open accessEfficient liquid exfoliation and dispersion formation of alkyl-terminated germananes
Reiko Azumi and Hiroaki Tachibana 2026 Jpn. J. Appl. Phys.
View article, Efficient liquid exfoliation and dispersion formation of alkyl-terminated germananesPDF, Efficient liquid exfoliation and dispersion formation of alkyl-terminated germananesWe report a simple preparation method for dispersions of alkyl-terminated germananes, GeCnH2n+1 (n = 1, 3, 6, 8, and 12), in halogenated solvents. The dispersion efficiency and suitable solvent were strongly dependent on the terminal alkyl-chain length; with appropriate combinations of alkyl-chain length and solvent identity, liquid exfoliation was achieved not only by ultrasonication but even by simple mechanical stirring at room temperature. Sufficiently long alkyl chains facilitated exfoliation by expanding the interlayer spacing; however, the dispersion concentration did not simply increase monotonically with alkyl-chain length. These results indicate that the behavior of dispersions is governed by a balance among interlayer expansion, solvent affinity for the alkyl-chain region, and kinetic processes such as reaggregation and sedimentation. This mild and practical method may provide a useful route toward solution processing of alkyl-terminated germananes.
- The following article is Open accessEffect of focal height on Faraday rotation distributions for magnetization analysis of magnetic holograms in Bi:RIG films using transmission scanning magneto-optical microscopy
Tsubasa Ebihara et al 2026 Jpn. J. Appl. Phys.
View article, Effect of focal height on Faraday rotation distributions for magnetization analysis of magnetic holograms in Bi:RIG films using transmission scanning magneto-optical microscopyPDF, Effect of focal height on Faraday rotation distributions for magnetization analysis of magnetic holograms in Bi:RIG films using transmission scanning magneto-optical microscopyWe developed a scanning magneto-optical microscope to quantitatively evaluate three-dimensional magnetization distributions within magnetic holograms. By scanning a focused laser beam, we measured the focal-height-dependent Faraday rotation angle distributions of magnetic fringes in bismuth-substituted rare-earth iron garnet films. The rotation angle amplitude exhibited characteristic changes with focal height, governed by the magnetic fringe geometry and the laser's conical divergence. This divergence alters the effective probe region within the magnetic domains as the focal height varies. Numerical calculations based on a geometric model of the laser transmission successfully reproduced these experimental trends, including non-monotonic amplitude recoveries. This focal-height dependence provides a robust basis for estimating depth and spatial structure in embedded magnetic features, showing strong potential for reconstructing three-dimensional magnetization distributions.
- The following article is Open accessX-ray scintillation properties of an InGaN/GaN superlattice thin film
Akinori Iwai et al 2026 Jpn. J. Appl. Phys.
View article, X-ray scintillation properties of an InGaN/GaN superlattice thin filmPDF, X-ray scintillation properties of an InGaN/GaN superlattice thin filmAn 11-μm-thick InGaN/GaN superlattice was investigated as a fast X-ray scintillator. The superlattice exhibited a dominant emission peak at 412 nm. Biexponential fitting of the scintillation decay curve yielded a dominant decay component of 5.39 ns, while the second component accounted for only 0.34% of the total initial amplitude. Pulse-height measurements under 5.9- (55Fe) and 59.5-keV (241Am) irradiation showed clear photoabsorption peak. After correcting for the wavelength-dependent sensitivity of the photodetector and nonproportionality of GAGG:Ce, the light yield at 59.5 keV was estimated to be approximately 27,000 photons MeV-1.
- The following article is Open accessVirtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutions
Satoshi Murasugi et al 2026 Jpn. J. Appl. Phys. 65 208003
View article, Virtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutionsPDF, Virtual discovery and experimental validation of tetracene-doped Ph-BTBT-C10 crystalline solid solutionsImpurity doping of semiconductors is an important technique for controlling electronic and optical properties. However, it remains challenging to dope crystalline organic semiconductors, since the difference in molecular shapes and charge distribution between host and guest compounds easily degrade the crystallinity. In this study, we conducted a large-scale virtual screening of guest compounds capable of forming solid solutions with 2-decyl-7-phenyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-C10) host crystals. Tetracene was one of the suitable guest molecules found in this study. Tetracene-doped Ph-BTBT-C10 crystalline solid solutions were experimentally validated with the powder X-ray diffraction and photoluminescence spectra. These results demonstrate that our computational screening method is an effective approach for efficiently discovering crystalline organic semiconductor solid solutions.
- The following article is Open accessPhotovoltaic characteristics and high-power excitation limits of InGaN-based laser power converters
Ichinori Kan et al 2026 Jpn. J. Appl. Phys. 65 206801
View article, Photovoltaic characteristics and high-power excitation limits of InGaN-based laser power convertersPDF, Photovoltaic characteristics and high-power excitation limits of InGaN-based laser power convertersThis study elucidates the fundamental photovoltaic characteristics of a laser power converter based on a p–i–n InGaN diode using external quantum efficiency (EQE) measurements and current–voltage measurements under various excitation conditions. The EQE spectrum shows an absorption band extending from 370 nm to 450 nm, where the reduction on the short-wavelength side is due to absorption in the n-type GaN layers. With increasing excitation power density, the conversion efficiency initially increases slightly, but non-radiative recombination significantly affects the open-circuit voltage (as well as the conversion efficiency) above ∼10 W cm−2. This critical excitation power density is more than 30 times higher than that of Si and InGaAs photodiodes, which highlights the suitability of InGaN-based devices for high-power photonic energy conversion. Furthermore, the excitation power dependence of the efficiency resembles that of the FF, which significantly degrades above 10 W cm−2 due to an increase in the series resistance.
- The following article is Open accessReduction of hydroxyl groups in optical nanofibers via in-fiber laser heating
Koki Oguri et al 2026 Jpn. J. Appl. Phys.
View article, Reduction of hydroxyl groups in optical nanofibers via in-fiber laser heatingPDF, Reduction of hydroxyl groups in optical nanofibers via in-fiber laser heatingOptical nanofibers fabricated using a standard oxyhydrogen flame exhibit optical losses at wavelengths around 1385 nm due to absorption by embedded hydroxyl groups, posing a challenge for the realization of quantum electrodynamics systems using ytterbium atoms. Here, we establish a method for the reduction of hydroxyl groups by heating them with a laser guided within the optical nanofiber under vacuum conditions. The temperature of the optical nanofiber during heating is estimated by monitoring the phase shift of the transmitted light using an interferometer. As a result, evidence suggesting that hydroxyl groups were desorbed by laser heating was obtained.
- The following article is Open accessSpatially resolved probing of near-field magnetic shielding by planar micro-metallic loops in the GHz range
Hiroya Tanaka et al 2026 Jpn. J. Appl. Phys. 65 207501
View article, Spatially resolved probing of near-field magnetic shielding by planar micro-metallic loops in the GHz rangePDF, Spatially resolved probing of near-field magnetic shielding by planar micro-metallic loops in the GHz rangePrecise control of near-field magnetic fields is essential for advancing microwave devices in quantum sensing and computing applications. In this study, we present a near-field magnetic shield based on a microscale planar metallic loop array operating in the GHz range. The fundamental shielding properties are elucidated through the analysis of a single loop element. Utilizing optically detected magnetic resonance and Rabi oscillation measurements of nitrogen-vacancy centers in diamond, we directly probe the microwave magnetic field in proximity to the loop element. Our measurements demonstrate that loop structures with a width of 200 μm attenuate the local magnetic field by approximately 70% at 2.84 GHz. Furthermore, numerical simulations reveal that effective shielding is preserved for loop widths down to several micrometers. These findings provide valuable design guidelines for near-field magnetic field management and provide a scalable strategy for mitigating unwanted magnetic flux in integrated microwave devices.
- The following article is Open accessEnergetics of hexagonal boron nitride nanoflakes adsorbed on hexagonal boron nitride sheet
Nadia Sultana et al 2026 Jpn. J. Appl. Phys.
View article, Energetics of hexagonal boron nitride nanoflakes adsorbed on hexagonal boron nitride sheetPDF, Energetics of hexagonal boron nitride nanoflakes adsorbed on hexagonal boron nitride sheetThe energetics of triangular hexagonal boron nitride (hBN) nanoflakes with clean edges are studied using density functional theory (DFT), with particular attention to their size and edge. Formation energies of triangular hBN nanoflakes depend on the flake size, edge termination, and chemical potentials of B and N atoms: The flakes prefer N termination when borazine (B₃N₃H₆) and ammonia borane (BNH₆) are their source molecules, whereas B termination is stabilized for diborane (B₂H₆) molecule. The energetics of the flakes on the hBN sheet are also investigated to provide theoretical insight into the nucleation processes of the hBN bilayer. The flakes are bistable at or around the angles of 0˚ and 60˚, corresponding to AA’ and AB stacking, respectively. The energy barriers for rotation increase with increasing flake size, indicating that the stacking orientation of the hBN bilayer is determined at the early stage of nucleation.
- The following article is Open accessIn-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yoke
Mitsunori Miyamoto et al 2026 Jpn. J. Appl. Phys. 65 20SP01
View article, In-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yokePDF, In-situ measurement for drain current of SiC-MOSFET using optical-probe current sensor with half-open loop magnetic yokeIn recent years, the switching frequency of power converters has increased significantly with the widespread adoption of wide-bandgap power semiconductors. Conventional sensors, such as current transformers and Rogowski coils, are limited by their size and frequency bandwidth, making accurate current measurement difficult. The optical probe current sensor developed by the authors is effective for high-frequency current measurements due to its compact sensor head and wide bandwidth (DC to 150 MHz). Although this sensor can measure magnetic fields in narrow spaces, measuring wideband current in wide conductors like busbars or copper traces remains challenging due to skin and proximity effects. In this study, we improved the frequency response of the sensor by integrating it with a half-open loop magnetic yoke that homogenizes the magnetic field around the conductor. Finally, we report the in-situ measurement results of the drain current flowing through a SiC-MOSFET during a double-pulse test using the proposed sensor.
- The following article is Open accessEffects of bis(aminopropyl)disiloxane cross-linking on structural and ferroelectric properties of P(VDF-TrFE) films
Yasuko KOSHIBA et al 2026 Jpn. J. Appl. Phys.
View article, Effects of bis(aminopropyl)disiloxane cross-linking on structural and ferroelectric properties of P(VDF-TrFE) filmsPDF, Effects of bis(aminopropyl)disiloxane cross-linking on structural and ferroelectric properties of P(VDF-TrFE) filmsChemically cross-linked ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] films were prepared using 1,3-bis(3-aminopropyl)tetramethyldisiloxane (Bis-APTMDS), a diamine cross-linker containing a flexible siloxane segment. Fourier- transform infrared spectroscopy, X-ray photoelectron spectroscopy, and gel fraction analysis confirmed the formation of a chemically cross-linked network between P(VDF-TrFE) chains. Increasing the Bis-APTMDS content altered the surface morphology and slightly reduced the crystallinity while largely preserving the ferroelectric Form I crystalline phase. Cross-linking decreased the Young's modulus and increased the strain at break, indicating enhanced mechanical deformability. Although the positive remanent polarization decreased with increasing cross-linker content under the same applied electric field, it recovered to a value comparable to that of uncross-linked P(VDF-TrFE) under a higher maximum applied electric field. These results demonstrate that Bis-APTMDS cross-linking can enhance the mechanical deformability of P(VDF-TrFE) films while maintaining recoverable ferroelectric polarization, providing a promising strategy for the design of mechanically compliant ferroelectric polymer films for flexible piezoelectric devices.
- Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loading
Shinya Ohta et al 2026 Jpn. J. Appl. Phys. 65 20SP08
View article, Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loadingPDF, Electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loadingWe investigated the electromechanical response of multilayer porous fluoropolymer electret cells under light mechanical loading. A 26-layer cell was fabricated using corona-charged FEP/porous-PTFE/FEP electret films. The corona-treated films exhibited a surface potential difference of approximately −1.9 kV. Under quasi-static compressive loading at 2.0 N cm−2, generated charges of approximately 1.0–1.7 µC were obtained, depending on the sample. Under finger tapping, the apparent average force and stress level were estimated to be approximately 3–6 N and 1.5–6 N cm−2, respectively. Under continuous finger tapping at an average frequency of 5.4 Hz, the measured average output power was 231 µW. The harvested energy was rectified and stored, and the stored energy was used for BLE advertising and connection establishment with a previously paired receiving device. These results demonstrate the feasibility of applying multilayer porous fluoropolymer electret cells to energy-harvesting systems driven by relatively small human mechanical inputs.
- Precise evaluations of aging effect and phenomenology in the paraelectric phase of Pb(Mg1/3Nb2/3)O3–PbTiO3
Makoto Iwata et al 2026 Jpn. J. Appl. Phys. 65 15SP06
View article, Precise evaluations of aging effect and phenomenology in the paraelectric phase of Pb(Mg1/3Nb2/3)O3–PbTiO3PDF, Precise evaluations of aging effect and phenomenology in the paraelectric phase of Pb(Mg1/3Nb2/3)O3–PbTiO3The aging effect on permittivity as a function of time and temperature was precisely evaluated in the paraelectric phase of 70.5%Pb(Mg1/3Nb2/3)O3–29.5%PbTiO3 (PMN–29.5%PT). It was newly found that there are two relaxation processes for the aging effect. The time dependence of permittivity at each setting temperature could be analyzed, assuming a linear combination of two Williams–Watts functions. Experimental results on the aging effect were analyzed on the basis of the phenomenological theory, qualitatively reproducing the time and temperature dependences of permittivity. As a result of our analyses, we found that polar nanoregions in the paraelectric phase may grow over time at a constant temperature.
- Quenching-induced enhancement of ferroelectricity via electron density redistribution and Bi off-centering
Genki Izu et al 2026 Jpn. J. Appl. Phys. 65 15SP05
View article, Quenching-induced enhancement of ferroelectricity via electron density redistribution and Bi off-centeringPDF, Quenching-induced enhancement of ferroelectricity via electron density redistribution and Bi off-centeringThe structural origin of quenching-induced enhancement in the ferroelectricity of 0.95(0.33BaTiO3–0.67BiFeO3)–0.05Bi(Mg0.5Ti0.5)O3 ceramics was investigated using synchrotron radiation X-ray diffraction and electron density analysis. Rietveld refinement revealed that both as-sintered and quenched ceramics possessed a rhombohedral structure (R3m), and Bi ions were off-centered in the (100) directions at 300 K. Electron density analysis indicated that the quenching-induced enhancement in ferroelectricity originated from an enhanced asymmetry in the electron density distribution between the upper ([100], [010], and [001]) and lower ([
, [0, and [00) sites and a larger off-centering displacement of Bi ions. These cooperative mechanisms enhanced the local dipole moment associated with the off-centered Bi ions while suppressing polarization cancellation between the upper and lower sites, yielding enhanced spontaneous polarization along the [111] direction. These findings provide novel insights into the mechanisms underlying the quenching-induced enhancement in the functional properties of Bi-based, lead-free piezoelectric ceramics. - Antiferroelectric order and polarization fluctuations in tungsten bronze-type K2NdNb5O15 revealed by machine-learning molecular dynamics simulations
Hodaka Abe et al 2026 Jpn. J. Appl. Phys. 65 14SP06
View article, Antiferroelectric order and polarization fluctuations in tungsten bronze-type K2NdNb5O15 revealed by machine-learning molecular dynamics simulationsPDF, Antiferroelectric order and polarization fluctuations in tungsten bronze-type K2NdNb5O15 revealed by machine-learning molecular dynamics simulationsTungsten bronze-type K2NdNb5O15-based compounds are promising lead-free antiferroelectric (AFE) materials for energy-storage applications; however, the structural mechanism underlying their antiferroelectricity remains unclear. In this study, we investigated the polarization configuration in the AFE phase of K2NdNb5O15 using machine-learning interatomic potential-based molecular dynamics simulations. The simulation results revealed that the Nb cations on the two crystallographically inequivalent octahedral positions, namely the B1 and B2 sites, behave differently in the AFE phase; the B2-site Nb cations, together with the Nd cations, form antiparallel polarization clusters, whereas the B1-site Nb cations are dynamically disordered, hopping between two off-center positions. These findings indicate that the AFE phase of K2NdNb5O15 is a partially disordered antipolar state, in which the static AFE polarization order coexists with the dynamic dipole disorder.
- Evaluation of Nd:YAG and Nd,Ce:YAG transparent ceramics as near-infrared scintillators for remote high-radiation field monitoring and bioimaging
Keita Miyajima et al 2026 Jpn. J. Appl. Phys. 65 126002
View article, Evaluation of Nd:YAG and Nd,Ce:YAG transparent ceramics as near-infrared scintillators for remote high-radiation field monitoring and bioimagingPDF, Evaluation of Nd:YAG and Nd,Ce:YAG transparent ceramics as near-infrared scintillators for remote high-radiation field monitoring and bioimagingNd:YAG and Nd,Ce:YAG transparent ceramics were evaluated on their photoluminescence (PL) and scintillation properties. In addition, their applicability to some near-infrared (NIR) scintillation applications was evaluated. The Nd:YAG transparent ceramics exhibited NIR PL and scintillation originating from Nd3+ 4f–4f transitions. The Nd,Ce:YAG transparent ceramic sample exhibited not only the same emissions from Nd3+ 4f–4f transitions, but also visible PL and scintillation originating from the Ce3+ 5d–4f transition. Of the two investigated samples, the Nd,Ce:YAG sample exhibited higher scintillation intensity, and a 0.036 mGy h−1 lower detection limit of radiation dose-rates was obtained, which was the best value so far and satisfied the 0.1 mGy h−1 requirement for the remote high-radiation field monitoring application for the first time. Furthermore, NIR scintillation output was successfully detected by an InGaAs-CCD camera, through meat with a few centimeters long thickness. The results indicated the applicability of NIR scintillators for bioimaging applications.
- Verification of improved viscoelastic contact mechanics with a fractional viscoelastic model for AFM force curve analysis
Kanon Hasegawa et al 2026 Jpn. J. Appl. Phys. 65 10SP09
View article, Verification of improved viscoelastic contact mechanics with a fractional viscoelastic model for AFM force curve analysisPDF, Verification of improved viscoelastic contact mechanics with a fractional viscoelastic model for AFM force curve analysisIn conventional nanoscale characterization of elastomers by atomic force microscopy (AFM), analysis of the obtained force curve data has typically been conducted using elastic contact mechanics with adhesion. However, polymeric materials are essentially viscoelastic and show hysteresis. To address this issue, viscoelastic theories have been proposed, which incorporate the speed-dependent adhesion that originates from the viscoelasticity at the contact edge. In this framework, the standard linear solid (SLS) model has been commonly employed, which is insufficient to describe more complex behavior and limits its applicability to practical polymeric systems. Here, we extended viscoelastic contact mechanics by introducing a fractional viscoelastic model to capture a broader spectrum of relaxation behaviors. Force curves of several elastomers with different glass transition temperatures were analyzed, and the potential to extract a viscoelastic parameter that represents the distribution of the relaxation time from a single force curve was demonstrated.
- Single-laser multi-waveform THz-FMCW signal generation and ranging via photomixing in a delayed self-multiplexing system
Yiqing Wang et al 2026 Jpn. J. Appl. Phys. 65 10SP01
View article, Single-laser multi-waveform THz-FMCW signal generation and ranging via photomixing in a delayed self-multiplexing systemPDF, Single-laser multi-waveform THz-FMCW signal generation and ranging via photomixing in a delayed self-multiplexing systemIn this work, we propose a low-cost, structurally simple, and flexible photomixing-based system for generating multi-waveform Terahertz frequency-modulated continuous-wave (THz-FMCW) signals. The proposed approach employs only a single wavelength-tunable laser in combination with a delayed self-multiplexing system constructed from standard single-mode fiber. Using this scheme, three distinct THz-FMCW modulation waveforms with bandwidths exceeding 7 GHz are successfully generated. Furthermore, the generated THz-FMCW signals are applied to a Michelson-interferometer-based ranging system, achieving ranging errors below 1 cm. These results demonstrate that the proposed method provides an attractive solution for future THz-FMCW radar systems requiring high precision, low cost, and simplified yet flexible system architectures.
- Development of MoS2/SiO2/p-Si heterojunctions with an interfacial SiO2 layer tuned to an appropriate thickness by CVD
Rikiya Matsushima and Akihisa Ogino 2026 Jpn. J. Appl. Phys. 65 08SP26
View article, Development of MoS2/SiO2/p-Si heterojunctions with an interfacial SiO2 layer tuned to an appropriate thickness by CVDPDF, Development of MoS2/SiO2/p-Si heterojunctions with an interfacial SiO2 layer tuned to an appropriate thickness by CVDAppropriate control of the interfacial SiO2 thickness is required for the practical application of chemical vapor deposition (CVD)-based molybdenum disulfide (MoS2)/Si devices. This study demonstrates the direct growth of MoS2/SiO2/p-Si heterojunction, in which the SiO2 layer functions as an active interfacial layer, using a CVD process with a MoO3 precursor and p-Si substrates with a native oxide layer. Uniform monolayer MoS2 films were confirmed by optical microscopy, Raman spectroscopy, and photoluminescence measurements. X-ray photoelectron spectroscopy revealed that the interfacial SiO2 thickness after MoS2 synthesis was limited to 2.0 nm, which is suitable for maintaining carrier tunneling and enabling carrier transport. Ultraviolet photoelectron spectroscopy further clarified the work function and band alignment at the MoS2/SiO2/p-Si interface, indicating favorable energy band bending across the heterojunction.
- Multi-scale simulation of the full-scale demolding process for slanted gratings and optimization of demolding directions and mechanical properties of the working stamp
Takahide Nakamura et al 2026 Jpn. J. Appl. Phys. 65 08SP09
View article, Multi-scale simulation of the full-scale demolding process for slanted gratings and optimization of demolding directions and mechanical properties of the working stampPDF, Multi-scale simulation of the full-scale demolding process for slanted gratings and optimization of demolding directions and mechanical properties of the working stampUnderstanding the demolding behavior in nanoimprint lithography is essential for improving pattern fidelity in slanted grating structures formed using high-refractive-index (HRI) resins. However, the macroscopic demolding behavior governing the actual peeling process has not been fully clarified. In this study, we developed a multi-scale finite element simulation consisting of macroscale and microscale models to analyze demolding under practical conditions. The macroscale model captures global peeling deformation, and the microscale model evaluates detailed strain in patterned structures during demolding. The simulation revealed that strain distribution strongly depends on the demolding direction and the modulus of the working stamp, showing good agreement with experimental observations. The proposed approach provides a basis for developing a full-scale simulation platform applicable to diverse molding geometries and demolding methods, supporting process and material design for direct nanoimprint technologies.
- Development of two-terminal perovskite/Si tandem solar modules and their application to building-integrated and vehicle-integrated photovoltaics
Daisuke Adachi et al 2026 Jpn. J. Appl. Phys. 65 07SP17
View article, Development of two-terminal perovskite/Si tandem solar modules and their application to building-integrated and vehicle-integrated photovoltaicsPDF, Development of two-terminal perovskite/Si tandem solar modules and their application to building-integrated and vehicle-integrated photovoltaicsWe report our recent progress in the development of practical technologies for two-terminal perovskite/Si tandem solar modules, using fabrication methods developed for perovskite single-junction modules. These methods enabled us to confirm an independently measured efficiency of 19.4% for a 700 cm2 perovskite single-junction module. We also present tandem solar cell technology represented by a typical baseline perovskite/Si tandem solar cell that achieved an independently measured efficiency of 32.6% (active area: 1.02 cm2). Using upsized perovskite/Si tandem solar cells, we obtained a module power output of 59.2 W (in-house measurement). We discuss color‑tone stability under process variation, evaluate the impact of color-tone variations on current matching between the top and bottom cells, and demonstrate prototypes of a building-integrated photovoltaic (BIPV) module and a three-dimensional curved vehicle-integrated photovoltaic (VIPV) module to gain insights into the optical design required to tune module appearance for BIPV/VIPV deployment. These results outline a development pathway coupling efficiency gains, long-term durability, and aesthetic control for perovskite/Si tandem solar modules.
![$\overline 100]$](https://content.cld.iop.org/journals/1347-4065/65/15/15SP05/revision4/jjapae8fdeieqn1.gif)
![$\overline 10]$](https://content.cld.iop.org/journals/1347-4065/65/15/15SP05/revision4/jjapae8fdeieqn2.gif)
![$\overline1]$](https://content.cld.iop.org/journals/1347-4065/65/15/15SP05/revision4/jjapae8fdeieqn3.gif)
- Material science and device physics in SiC technology for high-voltage power devices
Tsunenobu Kimoto 2015 Jpn. J. Appl. Phys. 54 040103
View article, Material science and device physics in SiC technology for high-voltage power devicesPDF, Material science and device physics in SiC technology for high-voltage power devicesPower semiconductor devices are key components in power conversion systems. Silicon carbide (SiC) has received increasing attention as a wide-bandgap semiconductor suitable for high-voltage and low-loss power devices. Through recent progress in the crystal growth and process technology of SiC, the production of medium-voltage (600–1700 V) SiC Schottky barrier diodes (SBDs) and power metal–oxide–semiconductor field-effect transistors (MOSFETs) has started. However, basic understanding of the material properties, defect electronics, and the reliability of SiC devices is still poor. In this review paper, the features and present status of SiC power devices are briefly described. Then, several important aspects of the material science and device physics of SiC, such as impurity doping, extended and point defects, and the impact of such defects on device performance and reliability, are reviewed. Fundamental issues regarding SiC SBDs and power MOSFETs are also discussed.
- High-quality β-Ga2O3 single crystals grown by edge-defined film-fed growth
Akito Kuramata et al 2016 Jpn. J. Appl. Phys. 55 1202A2
View article, High-quality β-Ga2O3 single crystals grown by edge-defined film-fed growthPDF, High-quality β-Ga2O3 single crystals grown by edge-defined film-fed growthβ-Ga2O3 bulk crystals were grown by the edge-defined film-fed growth (EFG) process and the floating zone process. Semiconductor substrates containing no twin boundaries with sizes up to 4 in. in diameter were fabricated. It was found that Si was the main residual impurity in the EFG-grown crystals and that the effective donor concentration (Nd − Na) of unintentionally doped crystals was governed by the Si concentration. Intentional n-type doping was shown to be possible. An etch pit observation revealed that the dislocation density was on the order of 103 cm−3. Nd − Na for the samples annealed in nitrogen ambient was almost the same as the Si concentration, while for the samples annealed in oxygen ambient, it was around 1 × 1017 cm−3 and independent of the Si concentration.
- Physical reservoir computing—an introductory perspective
Kohei Nakajima 2020 Jpn. J. Appl. Phys. 59 060501
View article, Physical reservoir computing—an introductory perspectivePDF, Physical reservoir computing—an introductory perspectiveUnderstanding the fundamental relationships between physics and its information-processing capability has been an active research topic for many years. Physical reservoir computing is a recently introduced framework that allows one to exploit the complex dynamics of physical systems as information-processing devices. This framework is particularly suited for edge computing devices, in which information processing is incorporated at the edge (e.g. into sensors) in a decentralized manner to reduce the adaptation delay caused by data transmission overhead. This paper aims to illustrate the potentials of the framework using examples from soft robotics and to provide a concise overview focusing on the basic motivations for introducing it, which stem from a number of fields, including machine learning, nonlinear dynamical systems, biological science, materials science, and physics.
- TiO2 Photocatalysis: A Historical Overview and Future Prospects
Kazuhito Hashimoto et al 2005 Jpn. J. Appl. Phys. 44 8269
View article, TiO2 Photocatalysis: A Historical Overview and Future ProspectsPDF, TiO2 Photocatalysis: A Historical Overview and Future ProspectsPhotocatalysis has recently become a common word and various products using photocatalytic functions have been commercialized. Among many candidates for photocatalysts, TiO2 is almost the only material suitable for industrial use at present and also probably in the future. This is because TiO2 has the most efficient photoactivity, the highest stability and the lowest cost. More significantly, it has been used as a white pigment from ancient times, and thus, its safety to humans and the environment is guaranteed by history. There are two types of photochemical reaction proceeding on a TiO2 surface when irradiated with ultraviolet light. One includes the photo-induced redox reactions of adsorbed substances, and the other is the photo-induced hydrophilic conversion of TiO2 itself. The former type has been known since the early part of the 20th century, but the latter was found only at the end of the century. The combination of these two functions has opened up various novel applications of TiO2, particularly in the field of building materials. Here, we review the progress of the scientific research on TiO2 photocatalysis as well as its industrial applications, and describe future prospects of this field mainly based on the present authors' work.
- High-NA EUV lithography: current status and outlook for the future
Harry J. Levinson 2022 Jpn. J. Appl. Phys. 61 SD0803
View article, High-NA EUV lithography: current status and outlook for the futurePDF, High-NA EUV lithography: current status and outlook for the futureHigh-NA extreme ultraviolet (EUV) lithography is currently in development. Fabrication of exposure tools and optics with a numerical aperture (NA) equal to 0.55 has started at ASML and Carl Zeiss. Lenses with such high NA will have very small depths-of-focus, which will require improved focus systems and significant improvements in wafer flatness during processing. Lenses are anamorphic to address mask 3D issues, which results in wafer field sizes of 26 mm × 16.5 mm, half that of lower NA EUV tools and optical scanners. Production of large die will require stitching. Computational infrastructure is being created to support high-NA lithography, including simulators that use Tatian polynomials to characterize the aberrations of lenses with central obscurations. High resolution resists that meet the line-edge roughness and defect requirements for high-volume manufacturing also need to be developed. High power light sources will also be needed to limit photon shot noise.
- Base-Metal Electrode-Multilayer Ceramic Capacitors: Past, Present and Future Perspectives
Hiroshi Kishi et al 2003 Jpn. J. Appl. Phys. 42 1
View article, Base-Metal Electrode-Multilayer Ceramic Capacitors: Past, Present and Future PerspectivesPDF, Base-Metal Electrode-Multilayer Ceramic Capacitors: Past, Present and Future PerspectivesMultilayer ceramic capacitor (MLCC) production and sales figures are the highest among fine-ceramic products developed in the past 30 years. The total worldwide production and sales reached 550 billion pieces and 6 billion dollars, respectively in 2000. In the course of progress, the development of base-metal electrode (BME) technology played an important role in expanding the application area. In this review, the recent progress in MLCCs with BME nickel (Ni) electrodes is reviewed from the viewpoint of nonreducible dielectric materials. Using intermediate-ionic-size rare-earth ion (Dy2O3, Ho2O3, Er2O3, Y2O3) doped BaTiO3 (ABO3)-based dielectrics, highly reliable Ni-MLCCs with a very thin layer below 2 µm in thickness have been developed. The effect of site occupancy of rare-earth ions in BaTiO3 on the electrical properties and microstructure of nonreducible dielectrics is studied systematically. It appears that intermediate-ionic-size rare-earth ions occupy both A- and B-sites in the BaTiO3 lattice and effectively control the donor/acceptor dopant ratio and microstructural evolution. The relationship between the electrical properties and the microstructure of Ni-MLCCs is also presented.
- Growth of β-Ga2O3 Single Crystals by the Edge-Defined, Film Fed Growth Method
Hideo Aida et al 2008 Jpn. J. Appl. Phys. 47 8506
View article, Growth of β-Ga2O3 Single Crystals by the Edge-Defined, Film Fed Growth MethodPDF, Growth of β-Ga2O3 Single Crystals by the Edge-Defined, Film Fed Growth MethodThe successful growth of 2-in. β-Ga2O3 crystals by the edge-defined, film fed growth (EFG) method was demonstrated. The optimization of growth conditions for larger single crystalline β-Ga2O3 is discussed in detail. The seeding conditions of temperature and neck width were found to be the most important factors to grow single crystals. X-ray rocking curve measurements of β-Ga2O3 crystals were conducted to estimate the dislocation densities of the grown crystals. Etch pit densities (EPDs) of the β-Ga2O3 crystals were also measured using KOH solution to measure the dislocation densities. The results were discussed combining with crystal growth parameters such as neck width to clarify the mechanisms of propagation and the origin of dislocations in crystals from phenomenological and crystallographic points of view.
- Fundamental aspects, recent progress and future prospects of inorganic scintillators
Takayuki Yanagida et al 2023 Jpn. J. Appl. Phys. 62 010508
View article, Fundamental aspects, recent progress and future prospects of inorganic scintillatorsPDF, Fundamental aspects, recent progress and future prospects of inorganic scintillatorsThe present work reviews some fundamental aspects of scintillators, including the light yield, decay time, emission wavelength, afterglow, timing resolution and energy resolution. Following fundamental aspects, recently developed inorganic ceramic, glass and single crystal scintillators are introduced with some future prospects.
- Valence band ordering in β-Ga2O3 studied by polarized transmittance and reflectance spectroscopy
Takeyoshi Onuma et al 2015 Jpn. J. Appl. Phys. 54 112601
View article, Valence band ordering in β-Ga2O3 studied by polarized transmittance and reflectance spectroscopyPDF, Valence band ordering in β-Ga2O3 studied by polarized transmittance and reflectance spectroscopyThe polarized transmittance and reflectance spectra of β-Ga2O3 crystals are investigated, and the data are interpreted in terms of the monoclinic crystal band structure. The energies of the absorption edge can be divided into six ranges, and these ranges can be assigned to the transitions from the valence bands to the conduction band minimum according to the selection rules. The indirect bandgap-energy of 4.43 eV is smaller than the direct bandgap-energy of 4.48 eV at RT; and the energy difference of 0.05 eV nearly matches the theoretically calculated values of 0.03–0.04 eV.
- Diamond Field-Effect Transistors with 1.3 A/mm Drain Current Density by Al2O3 Passivation Layer
Kazuyuki Hirama et al 2012 Jpn. J. Appl. Phys. 51 090112
View article, Diamond Field-Effect Transistors with 1.3 A/mm Drain Current Density by Al2O3 Passivation LayerPDF, Diamond Field-Effect Transistors with 1.3 A/mm Drain Current Density by Al2O3 Passivation LayerUsing nitrogen-dioxide (NO2) adsorption treatment and Al2O3 passivation technique, we improved drain current (IDS) of hydrogen-terminated (H-terminated) diamond field-effect transistors (FETs). The Al2O3 passivation layer also serves as a gate-insulator in a gate region. Maximum IDS (IDSmax) of -1.35 A/mm was obtained for the diamond FETs with NO2 adsorption and the Al2O3 passivation layer. This IDSmax is the highest ever reported for diamond FETs and indicates that the Al2O3 passivation layer can stabilize adsorbed NO2, which increases the hole carrier concentration on the H-terminated diamond surface. In RF small-signal characteristics, the diamond FETs with NO2 adsorption and the Al2O3 passivation layer showed high cutoff-frequency (fT) and maximum frequency of oscillation (fmax) in a wide gate–source voltage (VGS) range (>10 V). This is because the Al2O3 gate insulator with a high potential barrier against hole carriers can confine and control the high concentration of hole carriers and then high forward-bias voltage can be applied without noticeable gate leakage current.
Journal resources
Journal information
- 1962-present
Japanese Journal of Applied Physics
Online ISSN: 1347-4065
Print ISSN: 0021-4922
