质子、中子、^(60)Co-γ射线辐照对电荷耦合器件饱和输出电压的影响

Degradation of saturation output of CCD induced by proton,neutron and cobalt-60 irradiation

对国产工艺的电荷耦合器件进行了质子、中子、^(60)Co-γ射线辐照试验,研究了不同粒子辐照对器件饱和输出电压的影响。试验结果显示在质子、γ射线辐照下,电荷耦合器件的饱和输出电压显著退化,而在1 Me V中子辐照下,饱和输出电压基本保持不变,表现出较好的抗中子能力。分析认为饱和输出电压的退化主要受电离总剂量效应影响,一方面辐射感生界面态导致阈值电压正向漂移使耗尽层可存储最大电荷量下降;另一方面电离辐射损伤使电荷耦合器件片上放大器增益减小导致饱和输出电压下降。

The key results of multiple saturation output characterization campaigns of charge coupled device（CCD） were presented. These characterizations encompassed proton, neutron and cobalt-60 irradiation tests at room temperature and annealing. This gives us the opportunity to discuss differences and similarities on CCDs of degradation of saturation output induced by proton, neutron and cobalt-60 radiation. The experiments show that the saturation output is degraded markedly induced by total ionizing dose, degradations of saturation output at different total dose and the recovery after annealing were compared, while no obvious degradation after neutron irradiation（neutron irradiation only induced displacement damage）. Mechanisms for these saturation output changes were discussed, saturated output degradation mainly caused by threshold voltage decreases of irradiation, resulting in full-well capacity decline. In addition, the gain of the output amplifier was decreased by total ionizing dose. Further insight on the underlying physical mechanisms could be gained by simulating the charged particle track influence on the pixel electric fields, along with the diffusion, drift, and recombination processes that occur between charge generation and collection.