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We applied the low-temperature bounding for fabricating base/collector junctions of Si-based bipolar transistor structures. The common-base current gain of fabricated bipolar transistors increased as the ambient temperature was raised up to 165°C, which suggests that the low-temperature bounding might be useful for fabricating high-performance heterojunction devices.
The electrical properties of GaAs/GaAs junctions fabricated by using surface-activated bonding (SAB) were investigated. We extracted the potential barrier heights at 300-°C-annealed GaAs/GaAs interfaces from their current-voltage characteristics measured at varied ambient temperatures and estimated the energy of charge neutral level ECNL and the density of interface states Dit.
We present a novel underwater atomic force microscope system (underwater AFM system), which is mountable on underwater vehicles or submersible seafloor platforms. The mission of the system is to observe microorganisms and microparticulates in situ, which are suspended and dispersed in deepwater, with high spatial resolution down to nanometer scale. The system is composed of three major technological...
Effects of annealing on SAB based Si/Si junctions were investigated by TEM observation and current-voltage (I–V) measurement. We observed amorphous like layer at the Si/Si interface prior to the annealing, which seemed to vanish after the annealing at 1000 °C. The I–V characteristics of Si/Si junctions showed that the current decreased when the junctions were annealed at comparatively lower temperatures...
The effects of annealing on p+-Si/n-4H-SiC heterojunctons fabricated by using surface-activated bonding (SAB) were investigated by current-voltage (I–V) and capacitance-voltage (C-V) measurements. I–V characteristics were improved and the flat-band voltages extracted from C-V characteristics were smaller by annealing at higher temperatures.
Effects of annealing on bonding interfaces of III–V-on-Si hybrid tandem solar cells were investigated. We observed amorphous layer at the interfaces prior to the annealing. We also investigated the effects of the annealing on the current-voltage characteristics of n+-GaAs/n++-Si and p+-GaAs/n++-Si junctions.
Effects of annealing on GaAs/Si bonding interfaces of III-V-on-Si hybrid tandem solar cells were investigated. Using a cross sectional transmission electron microscope, an amorphous layer was observed at the interfaces of GaAs/Si junctions that had been fabricated by the surface active bonding method. The amorphous layer vanished after the annealing at 400 °C. We also investigated the effects of the...
The effects of annealing on n-Si/n-4H-SiC junctions made by the surface activated bonding were investigated. Both the forward and reverse characteristics were improved by annealing at higher temperatures.
Si/mesa-etched Si p-n junction was fabricated by the reactive ion etching and the surface activated bonding. The SEM observation of their cross section indicated that the height of the mesa was approximately 13 μm. Their capacitance-voltage and current-voltage characteristics were also measured.
DONET, i.e., the dense ocean-floor network system for earthquakes and tsunamis has started its operation in the Nankai Trough, SW Japan in the early of 2010, and followed by the extension to the westward region as DONET2 in near future. DONET observatory is composed of various sensors such as broadband seismometer, seismic accelerometer, tsunami meter, etc. The present study focuses on quartz pressure...
The electrical properties of GaAs/Si heterojuctions fabricated by using surface-activated bonding were experimentally investigated. The results of measurements suggested that the heterostructures revealed type-II band lineup.
DONET (Dense Ocean-floor Network system for Earthquakes and Tsunamis) is a submarine cabled real-time observation network for earthquakes and tsunamis monitoring around the Nankai trough, southwestern Japan. The scheduled twenty observatories have operated since August 2011. Various sensors such as a broadband seismometer, a pressure gauge, a hydrophone, etc. are equipped with each observatory, because...
DONET, i.e., the dense ocean-floor network system for earthquakes and tsunamis has started its operation in the Nankai Trough, SW Japan in the early of 2010, and followed by the extension to the westward region as DONET2 in near future. DONET observatory is composed of various sensors such as broadband seismometer, seismic accelerometer, tsunami meter, etc. The present study focuses on bottom pressure...
The electrical properties of pn junctions, with various semiconductor materials with different doping concentrations fabricated by using surface-activated-bonding (SAB), were investigated by measuring their current-voltage (I-V) characteristics. The I-V characteristics of p+-GaAs/n++-Si, p+-GaAs/n+-Si, p+-Si/n+-Si, p++-Si/n+-InGaP, and p+-Si/n+-InGaP junctions showed ohmic-like properties. The interface...
For the Belle II experiment at the superKEKB accelerator, we have been developing a proximity focusing ring imaging Cherenkov counter using silica aerogel as a radiator (ARICH). 144-channel Hybrid Avalanche Photo-Detectors (HAPD) developed with Hamamatsu Photonics K.K. were adopted as the Cherenkov photon detectors for the ARICH. We confirmed that the HAPD has sufficient performance for the ARICH...
We developed a new type of a microcantilever biosensor resonating at the interface between air and liquid. The cantilever sensor has advantages in high signal-to-noise ratio (SNR) and high quality factor (Q-factor) for detecting bio-reactions because liquid damping acts on only one-side, and because there is no obstacle between detection, excitation lasers and the cantilever. (Fig. 1 (c)) Using the...
For the Belle-II detector, we are conducting R&D on proximity focusing ring imaging Cherenkov (RICH) detector using a silica aerogel as a radiator. A 144-channel HAPD (Hybrid Avalanche Photo Detector) is adopted as a photo-detector for the Aerogel-RICH. Because the typical gain of HAPDs is lower than conventional photomultipliers, we need high-gain and low-noise electronics for readout of the...
For the Belle II experiment, we are developing a proximity focusing ring imaging Cherenkov counter using a silica aerogel as a radiator. Recently, a new aerogel fabrication method, called “pin-hole drying”, was invented and remarkably improved optical transparency has been realized in the region of refractive index larger than 1.05. For the photo-detector, we have developed a 144-channel Hybrid Avalanche...
JAXA is carrying out research and development of a mobile robot (rover) aimed at base construction and searching for rocks and soils on the lunar surface. The target areas for base construction and lunar exploration are mainly in mountainous zones, and the moon's surface is covered by regolith. Achieving a steady run on such irregular terrain is the big technical problem for rovers. A newly developed...
Power semiconductors that are used under high voltage conditions in hybrid vehicles (HVs) are required to have a high destruction tolerance against cosmic rays as well as to meet conventional quality standards. This paper describes an investigation into the failure mechanism for single event burnouts (SEB) induced by cosmic rays in insulated gate bipolar transistors (IGBTs). Device destruction tolerance...
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