采用不同钝化工艺制备了一系列具有不同P/A比的变面积光电二极管器件.在77～147 K温度范围对器件R0A和1 000/T关系进行了分析,结果表明在该温度区间器件暗电流主要以扩散电流占主导.对器件的R0A分布进行了研究,77 K下HgCdTe薄膜内的体缺陷及非均匀性对器件性能产生了重要的影响；127 K下由于体扩散电流增加,缺陷对器件的作用显著弱化.77 K和127 K下器件R0A随P/A比增大而减小,表明表面效应对器件具有重要的影响.基于Vishnu Gopal模型对器件1/R0A值和P/A关系进行了拟合分析,证实了器件存在较大的表面漏电现象,且通过表面钝化工艺的改进,有效减小了表面效应对器件性能的影响.

A series of variable-area photodiode devices with different P/A ratio were prepared by different passivation processes. The relationship between R0A of the devices and 1 000/T was analyzed in temperature range 77～147 K. The result shows that the dark current of device is dominated by diffusion current in the temperature range. The distribution of R0A was studied. The bulk defects and non-uniformity in HgCdTe thin films have an important influence on the performance of the device at 77 K. Due to the increase of the bulk diffusion current at 127 K, the effect of the defect on the device is significantly weakened. R0A values of the devices decrease with the increase of P/A ratio, which indicates that the surface passivation has an important effect on the device at 77 K and 127 K. The relationship between R0A of the devices and P/A ratio was analyzed based on Vishnu Gopal model. The surface leakage of the device is confirmed, and the effect of surface passivation on the performance of the device is effectively reduced by the improvement of the passivation process.