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Featured researches published by Toshio Hirao.


IEEE Transactions on Nuclear Science | 1993

Single-event current transients induced by high energy ion microbeams

Isamu Nashiyama; Toshio Hirao; Tomihiro Kamiya; Hidenori Yutoh; Toshiji Nishijima; Hiroyoshi Sekiguti

Focused high-energy ion microbeams were applied to the study of the basic mechanisms of single-event upset. Waveforms of the current transients induced by He-, C-, O- and Fe-ion strikes on silicon diodes were measured by applying extremely low beam currents of an order of 10 fA and a wide-bandwidth digitizing sampling technique. Total collected charges are evaluated from the transient currents as a function of LET (linear energy transfer), bias voltage, and doping level, and are compared with theoretical values calculated using conventional single-event models. It is found that irradiation effects on the total collected charges can be explained by the introduction of displacement atoms calculated using Coulomb potential and the Kinchin-Pease model. >


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 2001

Development of a new data collection system and chamber for microbeam and laser investigations of single event phenomena

Jamie S. Laird; Toshio Hirao; Hidenobu Mori; Shinobu Onoda; T. Kamiya; Hisayoshi Itoh

Abstract A new target chamber and control system for temperature-based transient-IBIC and transient-LBIC measurements using the same experimental chamber is outlined. The system has been designed for both ultra-fast and relatively slow transient measurements as a function of temperature from 77 K to 450 K. The control system, implemented in the Labview environment, allows single ion scanning and transient acquisition on a set of oscilloscopes, for an array of temperatures and bias. The modularity of the system allows its use for a broad range of experiments from single event upset transient current measurements to scanning ion deep level transient spectroscopy charge transient measurements. In this paper, we describe the overall system and illustrate its potential by way of example.


european conference on radiation and its effects on components and systems | 2001

Temperature dependence of heavy ion-induced current transients in Si epilayer devices

Jamie S. Laird; Toshio Hirao; S. Onoda; H. Mori; Hisayoshi Itoh

We report on the temperature dependence of the heavy-ion transient-ion beam induced current response of Si epilayer devices from 80 to 300 K. The measurements were performed on a heavy-ion microbeam in conjunction with the new transient-ion beam induced current system developed at the Japan Atomic Energy Research Institute. Furthermore, we perform a detailed comparison with technology computer-aided design (TCAD) simulations and discuss the results in terms of TCAD modeling, experimental procedure, and the implications for temperature-related single-event upset modeling.


IEEE Transactions on Nuclear Science | 2000

Analysis of single-ion multiple-bit upset in high-density DRAMs

Akiko Makihara; H. Shindou; Norio Nemoto; Satoshi Kuboyama; Sumio Matsuda; T. Oshima; Toshio Hirao; H. Itoh; S. Buchner; A.B. Campbell

New types of multiple-bit upset (MBU) modes have been identified in high density DRAMs (16 Mbit and 64 Mbit). The identification of the mechanisms responsible for the new modes is based on detailed physical bit-map analysis.


Journal of Applied Physics | 2005

High-injection carrier dynamics generated by MeV heavy ions impacting high-speed photodetectors

Jamie S. Laird; Toshio Hirao; S. Onoda; Hisayoshi Itoh

The generation of single event transients generated by the impact of high-energy ions in high-speed photodetectors leads to bit error rate degradation in optical communications in radiation hard environments such as space. High-energy heavy ions, in particular, generate a submicron electron-hole pair plasma with a picosecond temporal profile that results in ultrahigh-injection carrier dynamics which induce large space-charge effects. These space-charge effects disturb the local electric field, thereby determining the peak and duration of a single event transient. In this paper, we examine the transient response of Si p-i-n photodetectors irradiated with focused single MeV heavy ions for a range of ion energies chosen to ensure the same end of range but different average plasma densities. We discuss the role of high-injection effects on the evolving spatiotemporal response with the aid of three-dimensional technology computer-aided design software. The result of both measurement and simulation points to ch...


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1995

Effects of micro-beam induced damage on single-event current measurements

Toshio Hirao; Isamu Nashiyama; T. Kamiya; T. Nishijima

Abstract Radiation damage introduced by the impact of heavy-ion micro-beams has been studied in connection with its effects on single-event transient currents, which are measured by the digitizing sampling method combined with focused ion micro-beams. It is found that the single-event currents decrease with increasing the repetition number of measurements and that there exists a linear relationship between the ion fluence and the reciprocal of the normalized single-event charge. A single-event damage equation is deduced, where the damage constant is proportional to the defect density calculated using either the Kinchin-Pease model or the TRIM code. Experimental techniques are developed to eliminate the effect of radiation damage.


IEEE Transactions on Nuclear Science | 2009

LET Dependence of Single Event Transient Pulse-Widths in SOI Logic Cell

Takahiro Makino; Daisuke Kobayashi; Kazuyuki Hirose; Yoshimitsu Yanagawa; Hirobumi Saito; Hirokazu Ikeda; Daisuke Takahashi; Shigeru Ishii; Masaki Kusano; Shinobu Onoda; Toshio Hirao; Takeshi Ohshima

Single event transient (SET) pulse-widths were measured as a function of linear energy transfer (LET) by using pulse capture circuits and simulated with mixed-mode 3-D device simulations. We found that the carrier recombination process dominates the LET dependence of the pulse-widths.


IEEE Transactions on Nuclear Science | 2007

Single-Event Burnout of Silicon Carbide Schottky Barrier Diodes Caused by High Energy Protons

Satoshi Kuboyama; Chihiro Kamezawa; Yohei Satoh; Toshio Hirao; Hidenori Ohyama

It was demonstrated that single-event burnout was observed in silicon carbide Schottky barrier diodes with high energy proton irradiation. The behavior was successfully explained using a failure density function based on the geometric distribution. Responsible spallation fragments to trigger the single-event burnout were identified by Geant4 simulations.


Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms | 1998

Development of a fast multi-parameter data acquisition system for microbeam analyses

Takuro Sakai; Tsuyoshi Hamano; Toshio Hirao; T. Kamiya; K. Murozono; J. Inoue; S. Matsuyama; S. Iwasaki; K. Ishii

Abstract A commercially available Personal Computer (PC)-based multi-parameter data acquisition system has been developed for ion microbeam analyses. The PC is equipped with a recent fast processor, a large volume of memory and a general multi-channel Analogue to Digital Converter (ADC) interface board. When a signal from an X-ray detector (PIXE), from a particle detector (RBS)or from others triggers this ADC for data acquisition. X-Y beam scanning control signals which indicate the beam position are also digitized at the same time. These data are addressed to the 3D matrices in the memory space, that consist of 1024 channels for the energy spectra and 150 × 150 pixels for corresponding the beam scan area. Real time data processing can be done in addition to this data acquisition by the fast processor with the large memory. Simultaneous PIXE and RBS elemental mapping and ion beam induced charge (IBIC) imaging on fine structure diodes have been demonstrated with this system.


IEEE Transactions on Nuclear Science | 2006

Anomalous Charge Collection in Silicon Carbide Schottky Barrier Diodes and Resulting Permanent Damage and Single-Event Burnout

Satoshi Kuboyama; Chihiro Kamezawa; Naomi Ikeda; Toshio Hirao; Hidenori Ohyama

It was demonstrated that Silicon Carbide Schottky Barrier Diodes exhibited anomalous charge collection with heavy ion irradiation. Consequently, the permanent damage and Single-Event Burnout was observed in spite of no known current sustaining mechanism. A model for the mechanism was proposed based on the device simulation

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Hisayoshi Itoh

Japan Atomic Energy Agency

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Jamie S. Laird

Commonwealth Scientific and Industrial Research Organisation

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Takeshi Ohshima

Japan Atomic Energy Agency

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Tomihiro Kamiya

Japan Atomic Energy Agency

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Hidenori Ohyama

Japan Atomic Energy Research Institute

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Satoshi Kuboyama

National Space Development Agency of Japan

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Eddy Simoen

Katholieke Universiteit Leuven

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Naomi Ikeda

Japan Aerospace Exploration Agency

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