HgCdTe红外探测器质子辐照位移损伤的退火机制研究

As the key component of the space optical detection system, the performance of infrared detector will be threatened by the energetic particles in the space application environment, resulting in device failure or performance degradation, and then seriously affect the safety and reliability of the space optical detection system. The results indicate that the energetic particles induced displacement damage can be annealed rapidly. But the present annealing effect research only concerned about the radiation response regularity and annealing regularity of the radiation sensitive parameters of the infrared materials and detectors. Meanwhile, the specific annealing characteristic of the radiation induced defects and the relationship among the defects, defect levels and radiation sensitive parameters have not been researched deeply. The radiation damage mechanism cannot be understood accurately. In this project, the HgCdTe infrared material and infrared detector are selected to be the research subjects. The degradation laws of defects and radiation sensitive parameters can be obtained by energetic proton irradiation under different temperature. Combining the isothermal annealing and isochronal annealing methods, the displacement damage of infrared materials and detectors can be obtained. The influence mechanism of the temperature to the annealing process of radiation induced damage will be analyzed. The relationship among the defects, defect levels and radiation sensitive parameters will be established. The annealing mechanism of the displacement damage of HgCdTe infrared materials and detectors will be revealed. The research results will provide theoretical and technical support for building universal displacement damage experiment method and analyzing the displacement damage mechanism of HgCdTe infrared detector.

作为空间光学系统的关键部件，HgCdTe红外探测器受到空间高能粒子辐照导致器件性能衰退甚至失效，严重影响光学探测系统的安全性和可靠性。研究结果表明高能粒子辐照导致的位移损伤具有明显的退火效应，但是退火效应的研究只针对材料和器件敏感参数的辐射响应规律及退火规律，并未针对辐射感生缺陷的具体退火特性以及辐射感生缺陷、缺陷能级、辐射敏感参数三者之间的关系开展深入研究，无法深入理解其位移损伤机理。本项目以HgCdTe红外材料和红外探测器为研究对象，通过不同温度质子辐照试验获得辐射感生缺陷及辐射敏感参数的退化规律，采用等温退火和等时退火结合的方法，获得材料和探测器位移损伤的退火规律，分析温度对辐射感生缺陷演化过程的影响机制，建立辐射感生缺陷与缺陷能级和辐射敏感参数之间的关系，揭示HgCdTe红外材料与红外探测器位移损伤的退火机制，为红外探测器位移损伤辐照试验方法的建立和损伤机理的分析提供方法和理论支撑

红外探测器是空间光学探测系统的关键部件，空间辐射损伤将导致器件性能衰退甚至失效，从而影响空间光学探测系统的可靠性。由于红外材料是窄禁带半导体，对温度非常敏感。退火现象在宏观上的表现是材料和探测器参数性能的恢复或加剧恶化，在微观上对应的是辐射感生缺陷的复合及重组的过程，因此必须针对红外探测器辐射损伤的退火效应开展研究，获得温度对器件辐射损伤的影响机制。通过本项目的研究，建立了512×1短波HgCdTe红外焦平面低温在线辐照测试试验系统，实现了红外焦平面暗电流、噪声、盲元等关键参数在线测试。通过不同辐射源及辐照温度和退火温度，获得了红外材料、红外探测器和红外焦平面经过辐照后参数退化规律，并分析了辐射损伤缺陷和退火温度对材料和器件性能退化的影响机制。研究发现，经过辐照后，材料的少数载流子寿命显著增加，这是由于当电子入射材料时，在器件中造成位移损伤，在材料中产生大量位移损伤缺陷，显著增大电子浓度。随着辐射注量的增加，材料空穴浓度逐渐减小。由于HgCdTe材料的少数载流子寿命与载流子浓度成反比，因此电子辐照使材料空穴浓度减小，导致材料少数载流子寿命增加；红外探测器经过辐照后，随着电子注量的增加暗电流迅速减小，室温退火后暗电流急剧恢复，同时，室温退火后的暗电流大于辐照前暗电流值，这是由于位移损伤在导带内或靠近导带底的位置引入施主型缺陷能级，使HgCdTe材料和器件的p区空穴浓度减小，少数载流子寿命增大，从而导致器件暗电流的减小；红外焦平面经过辐照后，暗电流、噪声和盲元的增加，分析认为，在较小位移损伤剂量下，暗电流的增加与位移损伤引入的SRH中心导致少子寿命减小有关。本项目的研究结果将为红外探测器位移损伤辐照试验方法的建立和器件的在轨维护提供理论和方法支撑。