碲锌镉晶体位错形成机理的三维动态逆向研究

CdZnTe crystal is one of the most popular materials which used as substrate of high performance infrared detectors, due to its fully matched lattice with HgCdTe. The dislocation defects of CdZnTe crystal will restrict the sensitivity of detectors. The mechanism of dislocation formation is always a scientific problem. The traditional wet etching method has the shortcoming of defect distortion, and cannot do dynamic inversion to the dislocation. In this project, a new method for the three-dimensional dynamic inversion of the dislocation in CdZnTe crystal is proposed. The advanced low damage reactive ion etching technology is used to reproduce the inverse process of crystal growth in real time. There is an obvious selectivity for the normal and defect area of CdZnTe crystal, which leads to the reveal of accurate information of dislocation morphology. Thus, the dislocation information of three-dimensional dynamic inversion can be learned. Online monitoring microscope will be combined with the etching equipment to obtain the real-time dislocation morphology information at the etching surface. The three-dimensional morphology figuration of the dislocation in the crystal can be restored finally by image fusion processing. With these three dimensional information, along with the growth parameters of CdZnTe crystal, and the result of energy spectrum and X-ray diffraction, the formation mechanism of dislocation can be revealed to provide scientific basis for the methods of dislocation suppression in CdZnTe crystals.

作为一种与碲镉汞晶格零失配的晶体，碲锌镉一直是高性能红外光电探测器的首选衬底。碲锌镉晶体位错缺陷会制约探测器灵敏度，其形成机理一直是研究的科学难题。传统的湿法腐蚀显现法存在缺陷形貌失真、无法动态反演的缺点。本项目提出一种可对碲锌镉晶体位错三维动态逆向成形的新方法。该方法采用先进的低损伤反应离子刻蚀技术，实时还原晶体生长的逆过程。利用反应离子刻蚀对碲锌镉晶体正常区域和缺陷区域之间的选择性差异，准确地获取位错的空间立体信息，实现位错成形的三维动态反演。基于刻蚀系统上集成的在线成像功能，实时获取刻蚀面形貌，进一步对图像信息融合还原位错的三维形态。结合碲锌镉晶体生长参数与能谱、X射线衍射表征，揭示位错形成机理，为碲锌镉晶体位错抑制的方法提供科学依据。

作为一种与碲镉汞晶格零失配的晶体，碲锌镉一直是高性能红外光电探测器的首选衬底。碲锌镉晶体位错缺陷会制约探测器灵敏度，其形成机理一直是研究的科学难题。本项目成功搭建了基于干法刻蚀和湿法腐蚀的CdZnTe材料动态位错缺陷逆向成形的实验设施，并获得动态跟踪位错缺陷图像；发现了沉淀物腐蚀坑的形貌特性和堆积特性，区分出了位错腐蚀坑并得到了其穿越特性；通过跟踪位错腐蚀坑坑尖的位移情况，得到了坑尖移动的轨迹，获得了其形成机理和一般规律；通过对坑尖位移矢量S的深入研究，得到了位错线延伸方向的分布特征，并基于此发现了Nakagawa腐蚀剂对（111）A面的CdZnTe位错缺陷显现的局限性。提出了表征材料缺陷密度的新参数：不同{111}面上位错缺陷密度的比值（RDD）、穿越材料表面的位错密度（DDPS）、位错线体密度（BDDL），并得到了其与传统锥形腐蚀坑密度（PEPD）的关系，能够更真实的反映材料的位错密度。