【摘要】 表面漏电流引起的噪声会限制CdZnTe(CZT)探测器的性能,尤其对于共面栅探测器,漏电噪声的大小与器件的电极设计和表面处理工艺密切相关。本文比较了探测器表面的物理和化学钝化工艺:采用H2O2溶液和KOH KCl溶液对CZT样品进行湿化学钝化处理,采用RFPCVD法在CZT样品表面沉积类金刚石薄膜(DLC)进行物理干法钝化。借助俄歇电子能谱(AES)和显微拉曼光谱以及ZC36微电流测试仪等手段研究了CZT表面组成与器件电学性能之间的关系。AES结果表明KOH KCl溶液钝化可以改善CZT样品表面的化学组分比,H2O2溶液钝化可以将表面富Te层转化为高阻氧化层,钝化前后的I V特性曲线表明两种化学钝化方法均可以有效地减小器件表面漏电流,达到满意的钝化效果。CZT样品表面物理钝化通过在样品表面沉积DLC薄膜加以实现,显微拉曼光谱表明CZT表面钝化层是高sp3含量的DLC薄膜,AES深度剖析表明DLC薄膜可以有效阻止CZT内部元素的外扩散,并且DLC薄膜内部C元素向CZT内部的扩散也是比较低的。DLC薄膜钝化后的CZT共面栅探测器表面栅距25μm的栅间电阻可以达到12GΩ,有效地降低了器件的表面漏电流。更多还原

【Abstract】 The process of surface passivation of CdZnTe (CZT) plays a dominant role in detector performance, which can decrease the noise of the detectors and improve the spectral energy resolution. In this paper, we make a comparison between physical and chemical passivation processes. In particular, a new surface passivation technique for CZT has been investigated by depositing diamond like carbon (DLC) film with radio frequency plasma chemical vapor deposition (RFPCVD) method. The microstructures, chemical and electrical properties of the passivation layer have been analyzed by AFM, AES, Raman spectroscopy and micro-current testing. The results show that the passivation layer has the characteristic diamond peak of the sp~3 structure of the DLC, and the layer can prevent the outward diffusion of the components from CZT and C in the DLC layer only diffuse slightly into the surface of the CZT. The inter-strip resistance in a coplanar grid detector by the DLC passivation was about 12GΩ with inter-strip distance 25μm.更多还原