电流型碲锌镉探测器伽马灵敏度性能优化

Improvement onγ-ray Sensitivity of Current-mode CdZnTe Detector

为验证亚禁带光照对电流型碲锌镉(CZT)探测器伽马灵敏度性能优化的可行性,利用钴源装置开展了亚禁带光照对CZT探测器伽马灵敏度影响规律研究。结果表明:在稳态γ射线辐照条件下,CZT探测器输出电流随时间的变化曲线(标定电流曲线)存在前沿过冲现象。这一现象主要与晶体内深能级陷阱对载流子的去俘获过程有关。利用亚禁带光照能调控晶体内深能级陷阱的占据份额,消除CZT探测器标定电流曲线的前沿过冲,实现探测器性能优化。当亚禁带光(850 nm)在CZT探测器中引入的光照电流为33.0 nA、工作电压为200 V时,CZT探测器对能量约1.25 MeV的γ射线的灵敏度为9.99×10^(-17) C·cm^(2),接近理论模拟给出的1.18×10^(-16) C·cm^(2)。

In this paper,the feasibility of the improvement on theγ-ray sensitivity of current-mode CZT detector by sub-bandgap illumination was investigated.The effect of sub-bandgap illumination on the γ-ray sensitivity of CZT detector was analyzed by ^(60)Co source instrument.The results show that under stable γ-ray irradiation,the sharp peak in the output current-versus time curve(calibrated current curve)of CZT γ-ray detector was mainly related to the de-trapping effects of the deep level defect in CZT crystal.Illuminated by sub-bandgap light,the occupation of the deep level defect can be regulated.The sharp peak in the calibrated current curve can be eliminated and the performance of CZT detector can also be improved.When the photo-generated current induced by sub-bandgap illumination(850 nm)in CZT detector is 33.0 nA and the operated voltage is 200 V,the sensitivity of CZT detector to 1.25 MeV γ-ray is 9.99×10^(-17) C·cm^(2).This experimental sensitivity is close to the simulated sensitivity of 1.18×10^(-16) C·cm^(2).