摘要:
利用硅双极晶体管在线监测中子注量,其直流增益和损伤常数是作为探测器指标的重要参数.高温退火可使受到中子辐照的双极晶体管性能部分恢复,进而可以重复使用.开展高温退火特性研究,分析双极晶体管直流增益的恢复程度以及损伤常数的重复性.在快中子脉冲堆上对贴片型3DG121C双极晶体管进行三轮中子辐照,每轮辐照累计注量2.64×1013 cm-2.经过第一轮中子辐照后,双极晶体管直流增益下降至辐照前的40%,经过180 °C连续24 h的高温退火后,直流增益恢复至辐照前的67%;经过第二轮辐照后,直流增益下降至第二轮辐照前的50%,在相同条件下退火后,直流增益恢复至第二轮辐照前的73%;经过第三轮辐照后,直流增益下降至第三轮辐照前的58%,在相同条件下退火后,其直流增益恢复至第三轮辐照前的87%.三轮实验结果表明:双极晶体管直流增益倒数随辐照中子注量变化的线性关系基本一致,具体表现为其损伤常数具有很好的重复性.利用该高温退火特性,将双极晶体管作为中子注量探测器应用于快中子脉冲堆中子注量在线监测,监测结果与活化箔结果基本吻合.%The direct current gain and damage constant are important indexs, when silicon bipolar transistors is used for neutron fluence on-line detector.Neutron irradiation can degrade the bipolar transistor direct gain, and the performance would recover partly by high temperature annealing,so the detceor can be used repeatly.High temperature annealing characteristic of bipolar transistors have been done to analyse direct current gain recovering level and damage constant repetitive.The three rounds of irradiation-annealing experiments have been performed using unsealed bipolar transistors 3DG121C on fast burst reactor for fluence 2.64×1013 cm-2.After the first round of neutron irradiation, the current gain decrease to 40% of pre-irradiation and recovered to 67% of pre-irradiation after 24 h annealing at 180 °C.After the second round of neutron irradiation, the current gain decrease to 50% of before the second round irradiation and recovered to 73% of before the second round irradiation after the annealing process the same with the first round.After the third round of neutron irradiation, the current gain decrease to 58% of before the third round irradiation and recover to 87% of before the third round irradiation after the annealing process the same with previous two rounds.Three rounds of experiments have shown that the linear relationship between reciprocal current gain and neutron fluence is basically consistent, in other words, the radiation damage constants have a well repetitive.Concerning this high temperature annealing characteristic, the BJTs can be used as an online neuron fluence detector of equivalent neutron fluence monitor of CFBR-II reactor.The results basically agree with the results from activation foil.