高剂量X射线辐照下碲锌镉探测器的深度极化效应

采用双向辐照的方法研究了碲锌镉晶体中的深度极化效应,实验结果表明,深度极化效应与直接辐照的X射线剂量无关。通过对晶体内电场分布的模拟，进一步分析了深度极化的形成机制,认为深度极化效应与极化效应一样，都是由于高浓度的堆积电荷使得晶体内电势畸变从而阳极不能收集信号,但它与通常极化效应有所不同，造成这种极化的高浓度空间电荷是从更高浓度的空间电荷区扩散而来的，发生深度极化的区域本身并没有受到X射线的强烈辐照。

Further polarization effect of CdZnTe detectors under high flux X-ray irradiation

It has been observed that pixellated CdZnTe detectors fabricated from crystals experience a further polarization effect. In this case, in some areas of the CdZnTe detector, polarization occurs without high incident flux. Results from these studies reveal that at very high photon flux rates, a space charge region with high density develops and extends, consistent with the accumulation of positive space charge due to the trapping of free-carrier holes created by the X-ray irradiation. The further polarization is caused by the extending of space charge region. The extending of space charge region observed without high X-ray has a direct influence on the irradiation hardness and charge collection efficiency of the devices.