波长上转换红外探测器具有实现大面阵焦平面的优势,但光提取效率是制约器件整体效率的关键因素之一.本文主要研究利用表面微结构来提高波长上转换红外探测器的效率.首先通过仿真计算研究了表面微结构参数对光提取效率的影响,然后基于优化设计的参数,采用聚苯乙烯纳米球掩膜刻蚀的方法制作了具有圆台型表面微结构的波长上转换红外探测器.测试结果表明,具有表面微结构的器件的光提取效率比无表面微结构的器件提高了130%.本文制作表面微结构的方法可以实现波长上转换红外探测器件整体效率的提高.
In recent decades,infrared(IR)detection technology has been widely used in many fields such as weather monitoring,environmental protection,medical diagnostics,security protection,etc.With the progress and mature of the technologies,more attention has been paid to the imaging detections of weak IR signals.So the higher efficiency of the device is required.Moreover the next-generation IR photodetection technology focuses on large-scale,high-speed and low-dark-current imaging.The mechanical bonding between infrared detector chip and silicon readout circuit inevitably causes a thermal mismatch problem.Up-conversion IR photodetectors can solve the problem about the performance deterioration of photodetector and the thermal mismatch with silicon-based readout circuit,hence they have great advantages in realizing large-format focal plane array detection.However,the poor light extraction efficiency due to total reflection severely restricts the overall efficiency of the up-conversion device,which has become one of the bottlenecks to improve the device efficiency.In this paper,surface microstructures with micro-pillar morphology are designed and fabricated on quantum-cascade up-conversion IR photodetectors.The effect on the up-conversion efficiency is investigated by enhancing the light extraction efficiency.Firstly,by the optical ray retracing method,the influence of surface microstructure on light extraction efficiency is studied when considering different morphology parameters,and optimized surface microstructure is designed to possess a pillar base length of 150 nm,height of 105 nm and side wall angle of 75°.Then based on the results of simulation,up-conversion IR photodetectors with surface microstructures are fabricated using polystyrene nanospheres as mask.The self-assembled monolayer nanospheres are first etched to a proper size by using O2 plasma,then the patterns are transferred to Si Nxfilm,which acts as an ICP dry etching mask of the micro-pillars.Finally,the up-conversion device and a silicon detector ar