载流子输运性能对CdZnTe晶体脉冲X射线响应特性的影响  

Effects of charge carrier behaviors on the time response of CdZnTe crystals irradiated by pulsed X-rays

作　　者：徐亚东[1,2] 王昌盛[1] 谷亚旭 郭榕榕[1] 苏春磊[3] 介万奇[1] 

机构地区：[1]西北工业大学凝固技术国家重点实验室,西安710072 [2]南京大学固体微结构物理国家重点实验室,南京210093 [3]西北核技术研究所,西安710024

出　　处：《功能材料》2014年第24期24078-24081,24086,共5页Journal of Functional Materials

基　　金：国家重点基础研究发展计划(973计划)资助项目(2011CB6103);国家自然科学基金资助项目(51202197;51372205);高等学校博士学科点专项科研基金资助项目(20116102120014)

摘　　要：采用生长态高电阻CdZnTe晶体制备出平面电极探测器,室温下测试了其在脉冲X射线作用下的诱导电流曲线。分析了脉冲电流的上升时间以及脉冲衰减过程,发现脉冲上升时间约为2 ns,且不受外加偏压影响,而脉冲衰减过程可分为3阶段。利用α粒子结合飞行时间技术研究了CdZnTe晶体的载流子传输特性,分析了结构缺陷的散射和俘获-佉俘获对载流子传输特性的影响。同时对比了不同厚度的CdZnTe探测器在不同电压下对脉冲X射线的响应特性。结果表明,当外加电场强度增加时,诱导脉冲电流曲线的半峰宽呈指数衰减,但当探测器厚度大于0.2 mm时,随着探测器厚度的增加变化不明显。可能是由于材料中结构缺陷的浓度增加,对载流子的俘获和散射作用加剧,严重影响了载流子的传输过程和复合时间。As-grown high resistive CdZnTe crystals were employed to fabricate planar detectors.The pulsed X-rays induced transient current waveforms were obtained at room temperature.The rise time and decay time of the transient currents were evaluated.The rise time is approximately of 2 ns,which is independent on the bias voltage.The current decay can be divided into 3 parts.The charge transport behaviors were analyzed usingαparticles induced pulses combining with time of flight technique.The effects of structure defects on the charge carrier scattering and trapping-detrapping were discussed.In addition,the transient current waveforms of CdZnTe detectors with different thickness were compared as a function of bias voltage.The full wave at half maximum (FWHM)of the transient currents is exponential decay as the bias increases.However,the variation is limited when the detector is thicker than 0.2 mm,which is possibly attributed to the increasing trapping and scattering centers in the materials.Thus,the charge transport properties were degraded and the recombination time was prolonged.

关 键 词：CDZNTE 时间响应 脉冲X射线 载流子 俘获中心 

分 类 号：TN304[电子电信—物理电子学]