非制冷红外探测器阵列用热释电晶体的可控制备与尺度效应

Larger number of pixels and miniaturization are the most important trends of uncooled infrared deterctor arrays，in which the key technnologies are monopolied by foreign companies. Element pitch shall be reduced to 12～20 micormeters in next-generation uncooled infrared detector arrays. As a result, controllable fabrication and performance optimization of infrared detection materials in the micrometer scale should be very curial to develop chinese self-owned uncooled infared technology. Mn ion doped lead magnesium niobate titanate (Mn:PMNT) single crystal is a novel high performance pyroelectric material with super high figure of merit for detectivity, which was developed firstly by scientists from China. In this project, it is firstly proposed to put the Mn:PMNT pyroelectric single crystals to applications in next-generation uncooled infrared arrays. The research aims to overcome the difficulties in controllable fabrication of larger size Mn:PMNT pyroelectric crystals with high uniformity and low dielectric loss fluctuation, and high pyroelectric performance uncooled infrared detector array elements of micrometer scale.Two key fundamental problems will be addressed: The quantitative model of the physical mechanism for Mn ions doping effect in reducing dielectric loss, and micrometer scaling effect of the structure and pyroelectric properties and their modulation methods. The following specific researches will be included: Growth of larger size Mn:PMNT pyroelectric crystals with 3～4 inches diameter and enhanced Mn ions doping homogeneity. Reveal the quantitative relation between doped Mn ions content, polar defects, ferroelectric nanodomains and microdomains and the pyroelectric performance, especially the dielectric loss. Post-processing techniques will be optimized to further control and reduce the dielectric loss and suppress the loss fluctuation, which are the key factors influencing infrared detector array performance. Disclose the evolution of ferroelectric domains and pyroelectric properties with decreasing size of the machined array element to micrometer scale and enhance the pyroelectric performance of the elements through various electric field, external stress and atmosphered thermal annealing modulation processing. It is expected that micrometer-size infrared detector array element wth width less than 16 micrometers and thickness less than 8 micrometers shall be fabricated with high figure of merit for detectivity. The research will provide solid materials basis and meet the urgent requirments for China to develop next-generation infrared detector arrays with large pixel numbers and reduced size.

高像元数和微小型化是非制冷红外探测技术发展趋势,核心技术为国外垄断，新一代非制冷红外阵列阵元间距将降至12～20微米。本项目率先提出将我国首先研制成功的新型超高探测优值Mn掺杂铌镁钛酸铅(Mn:PMNT)热释电单晶应用于新一代红外探测器阵列，拟解决Mn离子掺杂降低介电损耗的定量化模型和微米尺度下结构与热释电性能变化规律及调控方法这两个关键基础问题，克服大尺寸、高均匀性热释电晶片和高性能微米尺度光敏元可控制备难题，具体研究：生长掺杂量均匀和直径3～4英寸Mn:PMNT热释电单晶；揭示掺杂量、偶极缺陷、铁电纳米畴和微畴等结构与介电损耗的定量化关系，优化后处理工艺降低介电损耗波动；阐释铁电畴和热释电性能在微米尺度上的变化行为，通过电场-应力-气氛热处理联合调控方法提高光敏元热释电性能，制备出宽度16微米和厚度8微米以下的高探测优值红外探测光敏元，为我国自主研制新一代非制冷红外探测器阵列奠定基础。

高像元数和微小型化是非制冷红外探测技术发展趋势，核心技术为国外垄断，新一代非制冷红外阵列阵元间距将降至12～20微米。项目率先提出将我国首先研制成功的新型高探测优值的Mn掺杂铌镁钛酸铅(Mn-PMNT)热释电单晶应用于新一代红外探测器阵列，解决了Mn离子掺杂降低介电损耗的定量化模型和微米尺度下结构与热释电性能变化规律及调控方法这两个关键基础问题，克服大尺寸、高均匀性热释电晶片和高性能微米尺度光敏元可控制备难题。研究并完成了如下工作：生长掺杂量均匀和直径3英寸以上的Mn-PMNT热释电单晶，通过改变组分和Mn掺杂含量，调控热释电单晶的相变温度、矫顽场和综合热释电性能，相变温度提高到218℃，矫顽场提高到10kV/cm，应变提高到±3%，介电损耗降低到0.05%；揭示掺杂量、偶极缺陷、铁电纳米畴和微畴等结构与介电损耗的定量化关系，优化后处理工艺，降低介电损耗波动至±8%以下；阐释铁电畴和热释电性能在微米尺度上的变化行为，通过电场-应力-气氛热处理联合调控方法提高光敏元热释电性能，制备出最小可达15μm×15μm，厚度最小可达6μm，热释电系数≥15×10-4 Cm-2K-1，介电损耗≤0.1%，探测优值≥21×10-5 Pa-1/2的高探测优值红外探测光敏元；采用分布式电极结构和电压模式电路，制备了新型的红外探测器，探测器在电压模式和电流模式下的比探测率D*分别达到了1.15×109 cmHz1/2/W和1.74×109 cmHz1/2/W，与基于Mn-PMNT(72/28)的探测器性能相当，为目前基于LiTaO3单晶的商用探测器3倍左右；针对火焰监测、气体探测等应用系统设计并制备了高响应的探测器，通过设计制备面积更大、厚度更薄的灵敏元，来提高探测器的响应电压；设计制备了气体传感器原型器件，初步实现了CO2气体的定性测量；制备了红外火焰探测器，与国内外探测器相比，信噪比分别提高了2.7倍和2.3倍。本项目提高了热释电单晶的综合热释电性能，拓宽了高性能热释电单晶的应用范围，降低了单晶的介电损耗，实现了微米量级光敏元的制备，并以此为基础研制出了高比探测率和信噪比探测器，为我国自主研制新一代非制冷红外探测器阵列奠定基础。