A uncooled α-Si infrared detector with novel thermal isolation method

A uncooled amorphous silicon (alpha-Si) infrared (IR) detector with novel thermal isolation method has been fabricated and characterized. The unique sandwich IR absorption structure based on polyimide (PI) and bottom metal reflective layer is presented. The fabrication process of the IR detectors is described. The absorption characteristics of the IR detectors have been investigated. The responsivity and detectivity of the IR detector are also discussed. The measurement results show that the polyimide layer exhibits good thermal isolating characteristics and the unique sandwich IR absorption structure is beneficial to the enhancement of detectivity. The TCR of alpha-Si film resistance is up to -2.8%. The detectivity of 1.7times10⁸ cmmiddotHz^1/2W^-1 is achieved with chopping frequency of 30 Hz at a bias voltage of 5 V. Compared with other IR detectors, the structures, using PI as thermal isolation layer, simplifies the fabrication process, reduces the cost and increases the yield. It is suitable for large-scale focal plane arrays (FPA).