Kazushi Hayashi

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RF power AlGaAs/InGaAs Pseudomorphic High Electron Mobility Transistors (PHEMTs) are widely used in satellite communication systems, transmit/receive modules for military radar applications, and cellular telephones. A high breakdown voltage (BV DG) is a necessary requirement for a device to achieve high P OUT. Increasing the gate-to-drain recess length (L(More)
GaAs PHEMTs are broadly used in RF power applications for wireless systems. A major concern with these devices is their gradual degradation as a result of prolonged biasing at high voltages. Previous research has identified the drain side of the device as the region that sustains most of the damage [1], but other mechanisms involving charge modulation under(More)
We have studied the degradation mechanism of AlGaAs/InGaAs pseudomorphic HEMTs (PHEMTs) under large signal operation. The output power of the PHEMT is degraded with increasing drain voltage (Vd), temperature, and humidity. The deteriorated devices show a decrease of the maximum drain current (Imax) around the knee voltage (Vk) and an increase of the drain(More)
SUMMARY We have investigated the microwave-detected photocon-ductivity responses from the amorphous In–Ga–Zn–O (a-IGZO) thin films. The time constant extracted by the slope of the slow part of the reflectivity signals are correlated with TFT performances. We have evaluated the influences of the sputtering conditions on the quality of a-IGZO thin film, as(More)
SUMMARY Microwave photoconductivity decay (μ-PCD) method was applied to evaluate the effects of chemical composition and Ar + plasma induced damage on the bulk and the surface states in amorphous In-Ga-Zn-O (a-IGZO) films. It was found that the peak reflectivity signal in the pho-toconductivity response increased with decreasing the Ga content, and had a(More)
The two-dimensional effect in the reverse gate leakage current of GaN HEMTs is studied by using the TCAD simulation. At the high voltage region, the extension of the potential from the gate to the drain latterly is important role for the reverse gate leakage current characteristics. On the other hands, the electrons flow vertically from the gate electrode(More)
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