A High Performance Uncooled a-Si TFT Infrared Sensor

This paper reports the theory, fabrication and testing of a novel uncooled infrared (IR) sensor using amorphous silicon thin film transistors (a-Si TFTs) as the active elements. The measured temperature coefficient of the channel current (TCC) of the a-Si TFT is about 4.18%/K at room temperature. What´s more, finger-cross TFT is designed, which can greatly improve the detectivity of uncooled infrared sensor by increasing the ratio of channel width to length (W/L). Nano-TiO₂ /polyimide (PI) hybrid membrane is applied in infrared absorption layer, which increases infrared absorptance by about 15%. A new thermal-isolation materials-polyimide is applied in uncooled infrared sensor, which not only has good thermal-isolation, but also simplifies the fabrication process and improves the yield. The whole process of a-Si TFT uncooled infrared sensor is compatible with the standard IC process. Preliminary experimental results show that a detectivity of 1.0 times 10⁹cmHz^frac12/W is achieved at a chopping frequency of 30 Hz