On the current transport mechanism in metal-semiconductor-metal structured CdZnTe radiation detectors
On the current transport mechanism in metal-semiconductor-metal structured CdZnTe radiation detectors
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金属—半导体—金属结构CdZnTe辐射探测器的电流传输机制
DOI：
10.1016/j.nima.2020.163445
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发表时间：
2020-03-21
影响因子：
1.4
通讯作者：
Jie, Wanqi
中科院分区：
文献类型：
--
作者：
Yu, Jingyi;Xu, Lingyan;Jie, Wanqi
CdZnTe辐射探测器的电流-电压特性与器件的性能密切相关。本文通过数值模拟宽偏置范围内的静态工作状态，研究了金属-半导体-金属结构的CdZnTe辐射探测器的暗电流传输机制。仿真电流电压特性与实验结果一致。通过基于计算的器件工作状态比较不同的电流传输理论来确定各种偏置和势垒条件下的主要电流分量。对于具有大势垒高度的肖特基接触，反向偏置的阴极决定低偏置范围内的电流，其中电流受到耗尽层中载流子的产生和扩散的限制。否则，如果势垒相对较小，则电流会受到高电阻率块体材料的限制。然而，当器件在高偏置范围内完全耗尽电子时，来自正向偏置阳极的注入空穴是主要的移动电荷并产生快速电流增加。对于电子势垒高度小于空穴势垒高度的欧姆接触，由于电子空间电荷限制电流，电流-电压曲线在高偏置范围内偏离线性关系。从仿真结果来看，提出了一种双整流电极结构，可以显着降低CdZnTe辐射探测器的暗电流。
The current-voltage properties of CdZnTe radiation detectors are closely related to the device's performance. In this paper, the mechanisms of the dark current transport in metal-semiconductor-metal structured CdZnTe radiation detectors are investigated by numerically simulating the static working states in a wide bias range. Simulated current-voltage characteristics are consistent with the experimental results. The major current components in various bias and barrier conditions are determined by comparing different current transport theories based on computed device working states. For Schottky contacts with large barrier heights, the reverse-biased cathode determines the current in the low bias range, where the current is limited by carrier generation and diffusion in the depletion layer. Otherwise, the current is restricted by the high-resistivity bulk material if the barrier is relatively small. However, when the device is fully depleted of electrons in the high bias range, injected holes from the forward-biased anode are the dominating mobile charges and produce a rapid current increase. For ohmic contacts where the electron barrier height is smaller than the hole barrier height, the current-voltage curves deviate from the linear relationship in the high bias range due to the electron space-charge-limited current. From the simulation results, a double-rectifying electrode configuration is proposed, which can significantly reduce the dark current of CdZnTe radiation detectors.