基于空间应用的CdMnTe新型核辐射探测器的研究

CdMnTe (CMT), as an excellent ternary compound semiconductor material with advantages of its wider band gap energy, higher average atomic number and lower segregation potential, can be considered as a promising alternative material to CdZnTe for the manufacture of room-temperature nuclear radiation detectors. The CMT radiation detector has great applications in experiments of high-energy physics, astrophysics and cosmic rays, biological, industrial, security detection, nuclear medicine, X-ray imaging and so on. In this proposal, CMT crystals grown by vertical Bridgman and Te solution vertical Bridgman methods, will be adopted to study the defects in crystal, including point defects, Te-rich phases and twins. The forming mechanism of twins will be investigated and its theoretical model of forming process will be established. The effects on the crystal properties, as well as corresponding detector performance of twins and its introduced defects, such as Te inclusions and dislocations, will be analyzed. Ohmic and Schottky contact electrode preparation process, detector package, signal electrode deposition and other technologies will be employed to achieve low leakage current and consistent metal-semiconductor contacts. The front-end amplifier circuit will be designed and adjusted to achieve the best performance, for fabrication of CMT detector prototype with excellent detection performance.

碲锰镉（CdMnTe，简称CMT）晶体是一种性能优异的新型三元化合物半导体材料，具有禁带宽度大、平均原子序数高和低分凝系数等优点，可作为替代 CdZnTe 成为辐射探测器的主要候选材料，在高能物理、天体物理和宇宙线、生物、工业、安全检测、核医学、X光成像等方面有着重要的应用前景。本项目基于Bridgman法和Te溶液Bridgman法生长的CMT晶片，研究CMT晶体中的点缺陷、Te夹杂相和孪晶等缺陷。了解孪晶的形成机制，建立理论模型，研究孪晶及其引入缺陷对晶体性能和探测器性能的影响。通过摸索欧姆接触电极、肖特基电极的制备工艺，探测器封装和信号电极引出等关键技术，得到良好的金属-半导体接触和具有低漏电流的CMT探测器。研究CMT探测器读出电路的调试与匹配，制备出探测性能优良的探测器样机，为CMT探测器在未来空间探测的应用打下坚实基础。

碲锰镉(CdMnTe，简称CMT)作为性能优异的室温核辐射探测器材料，可广泛应用于天体物理、核医学、环境监测和工业无损检测等领域。本项目基于熔体和Te溶液Bridgman法生长的CMT晶片，观察晶体中的点缺陷、Te夹杂相和孪晶，研究α粒子和质子对晶体的辐照损伤。对CMT探测器的电极制备和电学性能进行研究，并对影响探测器性能的因素进行分析。设计了探测器读出电路，研制出探测器原理样机，为CMT探测器在未来空间探测应用打下基础。.熔体法和溶液法生长的晶体的夹杂相密度为(0.75～2)×104cm-3和(7~9)×104 cm-3，位错密度为(0.8~5)×104 cm-3和(3~5)×105 cm-2。PL谱中Dcomplex峰的反常温度依赖现象可归因于晶体中较多的Te夹杂。孪晶是晶体生长降温过程中的固态相变所致，孪晶面为{111}面，大多为共格孪晶。CMT对α粒子和质子的电离能损远大于位移能损，随着粒子能量增加，空位数逐渐增加，当粒子的入射角大于60°时，空位数减少。.制备出Au/CMT/Au MSM结构，电阻率为1.51×1010 Ω•cm，界面层的透过系数、分压系数和厚度分别为0.026、9.447×10-5和3.008nm。制备的Au/CMT/Al和Au/CMT/Ni形成了良好的肖特基二极管结构，在-500V和-300V时的漏电流分别为-2.24nA和-0.77nA。采用Geant4对影响平面探测器性能的因素进行分析，(μτ)e/(μτ)h越小，收集效率越高，能量分辨率越好。增加工作电压可提高收集效率和能量分辨率。.采用单通道集成ASIC芯片研制出CMT原理样机，在-400 V条件下，MSM探测器对59.5 keV的能量分辨率为12.51%，(μτ)e为1.049×10-3 cm2/V。当偏压≤400 V时，能量分辨率由收集效率决定，当偏压>400 V时，则由漏电流决定。