CMOS图像传感器电子辐照实验的研究

研究了电子辐射剂量对CMOS图像传感器性能的影响,性能参数为平均暗电流输出和光强响应度。搭建了电子辐射场和光强响应度的测量系统,在器件处于工作状态和非工作状态下分别对其辐射,辐射剂量为:5103 rad、1104 rad、7104 rad、1105 rad、5105 rad。对于暗电流,当辐射总剂量超过7104 rad~1105 rad之间的某一个阈值时,暗电流随着辐射剂量的增长基本呈线性增加;光强响应方面,当器件处于非工作状态接受辐射时,辐射剂量对光强响应影响不大;当器件处于工作状态接受辐射时,辐射剂量超过7104 rad,光强响应曲线会下移,斜率减小,灵敏度降低。理论分析后,得到了暗电流随电子辐射剂量的变化模型。研究表明:长期工作于空间环境下的CMOS图像传感器,容易受到辐射总剂量效应的影响,需采取一定的防辐射措施。

Electron radiation experiment of CMOS image sensor

The effect of electron irradiation on CMOS image sensor was studied, focusing on average dark current and light intensity response. The CMOS image sensors, some in operating mode and the others in non-operating mode, were radiated simultaneously. The data were collected when the total dose of radiation reached 5103 rad, 1104 rad, 7104 rad, 1105 rad, 5105 rad, respectively. The results showed that, when the total dose of radiation exceed a threshold between 7104 rad and 1105 rad, dark current of the imager showed a basically linear relationship with the total dose of radiation. When concerning the light intensity response, for the imagers which were radiated in non-operating mode, radiation have no effect on the response; while for the imagers which were radiated in operating mode, with the total dose of radiation exceed a threshold, 7104 rad, the response curves shifted down and the slopes decreased with the total dose of radiation increased. In other words, radiation reduced sensitivity of the imagers. At last, the model of dark current versus total dose of electron radiation was developed after theoretical analysis. It is shown that after working in the space for a long time, CMOS image sensors are easily affected by the total dose effect of radiation, thus reasonable protection measures against radiation are needed.