1992 Fiscal Year Final Research Report Summary
EXPLANATION OF IMPURITY EFFECTS ON SI DETECTOR PERFORMANCE DETERIORATION DUE TO IRRADIATION
| Project/Area Number |
03640284
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
核・宇宙線・素粒子
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| Research Institution | RIKKYO UNIVERSITY |
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Principal Investigator |
SHIRAISHI Fumio RIKKYO UNIVERSITY, INSTITUTE FOR ATOMIC ENERGY, PROFESSOR, 原子力研究所, 教授 (20062606)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAMI Yasukiyo RIKKYO UNIVERSITY, INSTITUTE FOR ATOMIC ENERGY, PROFESSOR, 原子力研究所, 教授 (40062559)
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| Project Period (FY) |
1991 – 1992
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| Keywords | Si detector / Neutron irradiation / Radiation damage / Annealing / Infrared spectroscopy / Reverse current / Charge collection / Energy resolution |
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| Research Abstract |
In order to improve radiation resistant properties of Si detectors, we throughly investigated the following two subjects ; (1) effects of crystal impurities on detector performance deterioration due to radiation damage, and (2) annealing effects.
N-type Si wefers were irradiated with a fast neutron dose of 10^<13>/cm^2. After irradiation each wafer was annealed with an infra-red lamp furnace, a temperature range of 100 to 800ﾟC for 20 minutes. Though infra-red light absorption spectorscopy was carried out to the wafers in order to evaluate residual crystal imperfections, We could not idenify defect levels because of the insufficient sensitivity. We are now investigating other spectors-copy method such as photo-luminescence or electron spin resonance for identification of defect levels. Surface barrier detectors fabricated from the annealed wafers showed significant recovery in detector performances.
Especially annealings from 200 to 400ﾟC were effective for the recovery of detector characteristics. For example, leakage currents decreased by one to two orders and also energy resolutions for alpha particles recovered to a substantially same level as the value of a non-irradiated detector.
It was found that relatively low temperature annealings give at least ten times higher allowable exposure to radiation damages. This result is quite useful for the design or the fabrication of Si detectors in future.
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