Nippon Telegraph and Telephone Corporation, Nagoya University, and Hokkaido University successfully measured semiconductor soft error rates at continuously varying neutron energies from 1MeV to 800MeV. The findings reveal, for the first time, the complete picture of the energy dependence of semiconductor soft errors.
Data on soft error rate dependence on neutron energy are critical when studying the impact of cosmic rays on semiconductors and investigating countermeasures because the number of soft errors is heavily dependent on the incoming neutron energy. However, it has been impossible to measure data that have a wide and continuous energy range. Therefore, the soft error rates measured to date have been limited to several discrete neutron energy levels.
Researchers of Hokkaido University have developed an Ultra-high-speed error detection circuit that enables to precisely measure flight times of neutrons arriving at the semiconductor even if the velocities are close to the speed of light. From the flight time they could deduce the speed of the neutrons causing the soft errors. The circuit makes it possible to measure soft errors caused by neutrons across an extremely wide range of energies up to 800 MeV.
Soft error rates, which they measured successfully, are among the most basic and critical data to predict the number of soft errors caused by neutrons in various environments not only at ground level but also at high altitudes, in space, or even on another planet. The data will be useful in a variety of fields: evaluation of semiconductor reliability in space stations, study of soft error prevention measures to be taken in semiconductor materials, soft error tests using an accelerator, and simulation of the process in which soft errors occur.
The research results were published in IEEE Transactions on Nuclear Science on November 19, 2020. Click here to read the joint press release.
References: Hidenori Iwashita, Gentaro Funatsu, Hirotaka Sato, Takashi Kamiyama, Michihiro Furusaka, Stephen A. Wender, Eric Pitcher, and Yoshiaki Kiyanagi, “Energy-resolved Soft-Error Rate Measurements for 1-800 MeV Neutrons by the Time-of-flight Technique at LANSCE”, IEEE Transaction on Nuclear Science, 2020. https://ieeexplore.ieee.org/document/9201514 DOI: 10.1109/TNS.2020.3025727
Provided by Hokkaido University