为研究电荷耦合器件空间辐照效应、参数退化机理, 对国产64×64像元电荷耦合器件进行了中子辐照位移损伤效应研究。样品在中子辐照下, 暗信号、暗信号非均匀性和电荷转移效率等关键性能参数退化显著。研究结果表明: 暗信号的退化是由于中子辐照产生的体缺陷能级在耗尽层中充当复合-产生中心, 增大了热载流子的产生率所致, 而各像素单元暗信号退化的不一致性使暗信号非均匀性增大; 电荷转移效率显著减小则是由于中子辐照在转移沟道中产生的体缺陷不断捕获、发射电子所引起。在整个实验过程中, 饱和输出电压的退化可以忽略不计, 表现出较好的抗位移损伤能力。

Displacement damage effects due to neutron irradiations of charge coupled devices were presented through the analysis of the dark signals behavior in pixel arrays. When the fluence of neutron reached the predetermined point, the change of dark signal, dark signal non-uniformity, charge transfer efficiency and saturated output signal was measured off line. The major effect of neutron induced displacement damage on charge coupled device is the increase in dark signals as a result of carrier generation in the bulk depletion region of the pixel. Although the increase in the mean dark signals with neutron irradiation is important, the dark signals non-uniformity is generally the biggest concern for charge coupled device applications in space. Very large dark signals pixels can be produced when a collision occurs in a high electric field region of a pixel as a result of electric field enhanced emission. Another important performance parameter for a charge coupled device is the charge transfer efficiency, which is the fraction of signal charge transferred from pixel to pixel during read out. If a signal charge is trapped by neutron induced defect, and remains trapped for more than one clock cycle, it will be lost from the signal charge packet. Saturation output signal voltage does not have any obvious degradation even at the highest DDD level. The research will help the designers to know the radiation damage in charge coupled device and improve the tolerance by radiation hardening design.