Effects of Chemical Treatments on CdZnTe X-Ray and Gamma-Ray Detectors
Effects of Chemical Treatments on CdZnTe X-Ray and Gamma-Ray Detectors
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DOI：
10.1109/tns.2016.2527779
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发表时间：
2016-04-01
影响因子：
1.8
通讯作者：
James, Ralph B.
中科院分区：
文献类型：
--
作者：
Egarievwe, Stephen U.;Hossain, Anwar;James, Ralph B.
室温半导体探测器，如碲锌镉（CdZnTe），在制造过程中经常受到表面损伤，从而降低了它们探测X射线和伽马射线的性能。在这项研究中，我们比较了两种表面钝化化学溶液：过氧化氢中的氟化铵（NH 4F + H2 O2 + H2O）和过氧化氢中的氢氧化钾（0.1 g KOH + 10 ml 30% H2 O2）。X射线光电子能谱分析表明，NH 4F基溶液更有效地将CdZnTe表面的Te物种转化为更稳定的TeO 2层，Te 3d（3/2）O（2）/Te 3d（3/2）和Te 3d（5/2）O（2）/Te 3d（5/2）峰高比分别达到4.90和5.34，相比之下，KOH基溶液分别为1.25和1.19。的电流-电压测量结果表明，增加的体积漏电流为新鲜钝化的样品相比，机械抛光的样品。然而，在约3至14天的时间内，它们的漏电流降低到机械抛光样品范围内的值。CdZnTe样品的电阻率在10（10）Ω-cm的量级。基于NH 4F的化学品对漏电流的贡献较小。其在60 V下的漏电流是机械抛光样品的6.3倍，相比之下，用KOH基溶液钝化的样品为30.5倍。Am-241的59.5 keV峰的分析表明，与用KOH基溶液钝化的样品相比，用NH 4F基溶液钝化的样品具有更好的能量分辨率。
Room-temperature semiconductor detectors, such as cadmium zinc telluride (CdZnTe), often are subjected to surface damage during fabrication, thus reducing their performance in detecting X-rays and gamma-rays. In this study, we compared two surface-passivation chemical solutions: Ammonium fluoride in hydrogen peroxide (NH4F+ H2O2 + H2O) and potassium hydroxide in hydrogen peroxide (0.1 g of KOH + 10 ml of 30% H2O2). X-ray photoelectron spectroscopic analysis showed that the NH4F-based solution is more effective at converting Te species on the CdZnTe surfaces into a more stable TeO2 layer, attaining values of 4.90 and 5.34 for the Te3d(3/2)O(2)/Te3d(3/2) and Te3d(5/2)O(2)/Te3d(5/2) peak-height ratios respectively, compared to the KOH-based solution with 1.25 and 1.19, respectively. The current-voltage measurements showed an increase in the bulk leakage current for freshly passivated samples compared to those of mechanically polished samples. However, within a period of about three to 14 days, their leakage currents reduced to values in the range of the mechanically polished samples. The resistivity of the CdZnTe samples is on the order of 10(10) Omega-cm. The NH4F-based chemical contributed less to the leakage current. Its leakage current at 60 V is 6.3 times that of the mechanically polished sample, compared to 30.5 for the sample passivated with the KOH-based solution. Analysis of the 59.5-keV peak of Am-241 showed that the sample passivated with the NH4F-based solution has a better energy resolution compared to the one passivated with the KOH-based solution.