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We demonstrated the crystal growth of group-III arsenides (III-As) on GaN via an arsenidation layer and GaN-channel electron mobility transistors (HEMTs) with a regrowth InAs/GaAs source and drain (S/D) region. By annealing under an AsH3 atmosphere, the surface of a GaN (0001) template is arsenided. We grew ⟨ 111 ⟩ oriented InAs and GaAs on arsenided GaN. Silicon-doped n-type InAs with a carrier mobility of over 1500 cm2/V s and a carrier concentration of over 1 × 1019 cm−3 was successfully obtained. The fabrication process and direct-current characteristics of GaN-channel HEMTs with the regrown Si-doped InAs/GaAs S/D region were demonstrated for the first time. A maximum transconductance estimated from transfer characteristics was as high as ∼195 mS/mm for the HEMT with a gate length of 2 μm without passivation, which is comparable to those for the HEMT without any S/D regrowth. The impact of the InAs/GaAs S/D region on the on-resistance of the fabricated HEMTs was estimated to be ∼0.9 Ω mm, which can be reduced by optimizing the device structures and process conditions. These results indicate that the process of GaN arsenidation and III-As regrowth can be used without any device performance degradation. Therefore, further lowering the ohmic contact resistivity and on-resistance of GaN-channel HEMTs is possible by maturing the manufacturing-process technology of III-As-contained GaN-channel HEMTs. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the vibration serviceability and impact coefficient of a seven-span continuous cable-stayed bridge planned for an expressway extension using a three-dimensional vehicle–bridge coupled vibration analysis. For the bridge design, deflection under the designed live load of the continuous cable-stayed bridge did not meet the deflection limit specified in "Japanese Design Specifications for Highway Bridges." The excessive deflection indicates the possibility of poor vibration serviceability. To clarify the bridge vibration serviceability, the dynamic responses of the bridge and passing vehicles were examined using the three-dimensional vehicle–bridge coupled vibration analysis. The three-dimensional analysis was validated by comparing the vibration response of a single-span steel cable-stayed bridge in service subjected to vehicle running tests with those numerical responses from the three-dimensional analysis. The ride comfort of vehicles on the bridge was assessed in terms of vibration serviceability according to the ISO 2613-1 international standard for evaluating whole-body vibration exposure. The observation from the simulation-based investigation demonstrated that the vehicle response does not exceed the ride comfort limit irrespective of vehicle, road, and running conditions. In other words, the findings confirmed a negligible effect of large deflections on driving safety. The impact factors were found to be less than 1.05 for the main girder, less than 1.03 for the main tower base, and less than 1.04 for the cable. The impact factor was greatest when several vehicles were running at resonant headway. [ABSTRACT FROM AUTHOR]

Background: Psychological characteristics of eating behaviour may be related to dietary habits. Aim: We investigated the association between eating behaviour characteristics and nutrition and food intake adequacy in Japanese adolescents. Methods: This cross-sectional survey was conducted among 136 junior high school students (boys: 90, girls: 46) at a junior high school in Tokyo, Japan. Eating behaviour was categorised into three types (emotional, external, and restrained) using scores on the Japanese version of the Dutch Eating Behaviour Questionnaire. Dietary intake was assessed using a validated, brief self-administered diet history questionnaire. Inadequate nutrient intake was determined by counting the number of nutrients not meeting the dietary reference intake (DRI) for the Japanese population. The statistical analyses included Wilcoxon signed-rank tests, Spearman's rank correlation coefficient, and multiple regression analysis using JMP ver.14 (SAS Institute Inc., Cary, NC, USA). All reported p values are two-tailed, and p < 0.05 was regarded as statistically significant. Results: Multiple regression analysis showed that restrained eating score was inversely associated with the number of nutrients not meeting the DRI (β = − 0.28; p = 0.0027) and with total weight of snack intake (β = − 0.30; p = 0.0010). Neither emotional nor external eating was significantly associated with the number of nutrients not meeting the DRI and with total weight of snack intake. Conclusions: These results suggest that adolescents with low restrained eating scores may have less self-control over their eating behaviour and may therefore have inadequate dietary intake. [ABSTRACT FROM AUTHOR]

Next‐generation "Beyond 5G (B5G)/6G" wireless network systems have been researched and developed for meeting the rapid growth of mobile traffic. A high‐yield fabrication process of InP‐based transistors and tera‐hertz monolithic integrated circuits with 300 GHz operation is reported, which is a candidate frequency for "Beyond 5G/6G" network systems. The main focus is on a high‐yield and reproductive fabrication process of InP‐based high electron mobility transistors (HEMTs) while revisiting previous studies. The DC and radio frequency characteristics of fabricated InP‐HEMTs from the viewpoint of integrating circuits are described. Then, high‐frequency performances of ft = 280 GHz and fmax = 860 GHz in the bias conditions of Vgs/Vds = 0.2/1.1 V with good uniformity are obtained. Finally, InP‐based 300 GHz‐band mixer and power amplifiers are introduced, to which a backside process is also applied for ensuring their stability and enhancing output power. [ABSTRACT FROM AUTHOR]

This study investigates the trapping characteristics present at the interface of AlxGa1−xN/GaN high electron mobility transistors (HEMTs) and explores the influence of the Al composition within the AlxGa1−xN barrier on the device's performance. Using a single pulse ID–VD characterization technique, the reliability instability is evaluated in two different AlxGa1−xN/GaN HEMTs: one with an Al composition of 25% (Al0.25Ga0.75N/GaN) and the other with an Al composition of 45% (Al0.45Ga0.55N/GaN). The results unveil a notable higher drain current degradation (ΔID) in Al0.45Ga0.55N/GaN devices, attributed to fast transient charge trapping. Conversely, the Al0.25Ga0.75N/GaN device exhibits a substantial 35% reduction in interface trap density (Dit) and an impressive 73% decrease in border trap density (Nbt), solidifying its reduced trapping behavior compared to Al0.45Ga0.55N/GaN due to the rougher barrier/channel interface of the latter device. Furthermore, load‐pull measurements unveiled a noteworthy 60% power‐added efficiency for the Al0.25Ga0.75N/GaN device, presenting a 10% performance improvement over the Al0.45Ga0.55N/GaN device. These findings provide valuable insights into the trapping phenomena within AlGaN/GaN HEMTs, paving the way for enhanced device design and performance optimization. [ABSTRACT FROM AUTHOR]

The mean‐time‐to‐failure (MTTF) of AlGaN/GaN high electron mobility transistor is demonstrated by considering both voltage and temperature dependent electrical degradation in on‐wafer devices. The characteristics of threshold voltage shift (ΔVT) and gate leakage current (Ig_leak) after off‐state step and VDS = 0 step stress test are reported. The devices under test are being DC stressed (high operation life‐time test) in semi‐on‐state conditions at constant power dissipation of 2 W mm−1 for more or less than 200 h until the maximum drain current (Idmax) drops by 15%. Under low stress voltage (10 V), we find activation energies (Ea) and voltage acceleration factor (γ) to be 0.32 eV and 0.09 V−1, respectively, while increasing stress voltage up to 20 V results in increased activation energies of 0.68 and 0.16 eV. The MTTF is estimated to be 1.16 × 104 h at VDS = 20 V, while stressing at low bias gives a high MTTF of 2.20 × 104 h at VDS = 10 V. [ABSTRACT FROM AUTHOR]