Nuclear Engineering and Radiological Science Center, Department of Electrical Engineering and Computer Science, Alabama A&M University, Normal, AL 35762, USA.
National Security and Nonproliferation Department, Brookhaven National Laboratory, Upton, NY 11973, USA.
Sensors (Basel). 2019 Jul 25;19(15):3271. doi: 10.3390/s19153271.
Cadmium zinc telluride selenide (CdZnTeSe or CZTS) is one of the emerging CdTe-based semiconductor materials for detecting X- and gamma-ray radiation at or near room temperature (i.e., without cryogenic cooling). Potential applications of CZTS sensors include medical imaging, X-ray detection, and gamma-ray spectroscopy. Chemical passivation of CZTS is needed to reduce the conductivity of Te-rich surfaces, which reduces the noise and improves the device performance. In this study, we focus on the effect of surface passivation of CZTS using a 10% aqueous solution of ammonium fluoride. The effects of the chemical treatment were studied on the leakage current, charge transport measured as the electron mobility-lifetime (µτ) product, and the spectral resolution measured as the full-width at half-maximum (FWHM) of specific peaks. After passivation, the leakage current increased and began to decrease towards pre-passivation levels. The energy resolutions were recorded for eight applied voltages between -35 V and -200 V. The results showed an average of 25% improvement in the detector's energy resolution for the 59.6 keV gamma peak of Am-241. The electron µτ product was unchanged at 2 × 10 cm/V. These results show that ammonium fluoride is effective for chemical passivation of CZTS detectors.
碲化镉锌硒（CdZnTeSe 或 CZTS）是新兴的基于 CdTe 的半导体材料之一，可用于在室温或接近室温（即无需低温冷却）下检测 X 射线和伽马射线辐射。CZTS 传感器的潜在应用包括医学成像、X 射线检测和伽马射线能谱学。需要对 CZTS 进行化学钝化以降低富 Te 表面的电导率，从而降低噪声并提高器件性能。在这项研究中，我们专注于使用 10%的氟化铵水溶液对 CZTS 进行表面钝化的效果。研究了化学处理对漏电流、作为电子迁移率-寿命（µτ）乘积测量的电荷输运以及作为特定峰半峰全宽（FWHM）测量的光谱分辨率的影响。钝化后，漏电流增加，并开始向钝化前的水平下降。在-35 V 至-200 V 之间的八个应用电压下记录了能量分辨率。结果表明，对于 Am-241 的 59.6 keV 伽马峰，探测器的能量分辨率平均提高了 25%。电子µτ 乘积保持在 2×10 cm/V 不变。这些结果表明，氟化铵对 CZTS 探测器的化学钝化是有效的。
