微测辐射热计单元红外吸收分析

Analysis of Infrared Absorption for 25 μm Pitch Pixel of Micro-bolometer

介绍了一种计算多层结构微测辐射热计探测单元的红外吸收模型,并计算了所设计25μm微测辐射热计探测单元的红外吸收。当探测单元表面金属吸收层的方阻从2~600Ω/□变化时,单元的吸收功率先逐渐增大,之后缓慢下降。对于300 K黑体辐射,当探测单元的吸收层方阻达到332Ω/□时,吸收率达到最大。此时在8~14μm波段单元的红外吸收率平均值为72%,吸收功率为16 nW。在此基础上对探测单元结构的悬空高度进行优化,得到最优的两层悬空间隙高度均为0.8μm,最优吸收率为82%。

An infrared absorption model was described, which had been used for infrared absorption analysis for a 25 μm two-level micro-bolometer pixel design. If the square resistance of surface metal film was changing from 2 Ω to 600 Ω, the absorption power of the pixel was enhanced at first, then it was reduced gradually. In the radiation of 300 Kelvin black body, the best absorption happened when the square resistance of absorption layer increased to 332 Ω/[]. The highest absorptivity is 72%, corresponding absorption power is 16 nW. According to the highest absorptivity of the described 25 μm pixel, the vacuum gaps of the two-level pixel structure both had been optimized to 0.8 μm for further enhancing absorption.