Packaging carbon nanotube based infrared detector

Abstract

We present a fabrication and packaging method of carbon nanotube (CNT) based infrared (IR) sensor chip using parylene C layer. CNT was found to be sensitive under near IR radiation and it could be used as IR sensing element. Parylene C thin film was used as a conformal pin hole free insulating layer and oxygen barrier for protecting CNTs during the detection. The IR transmission properties of parylene C layer and the influence on the response of the CNT sensor were studied. Our experimental results showed that the CNT sensor without parylene C protection exhibited current change when it was exposed to the IR laser. The sensing current percentage changes decreased when the parylene C thin film substrate was placed between the CNT sensor and IR laser source. It implied the IR absorption behavior of parylene C thin film. We also found that the IR absorption level is proportional to the thickness of the parylene C layer. The parylene C packaged CNT sensor was fabricated and tested under near IR radiation. Preliminary results indicated that the CNT IR detector coated with parylene C was capable of sensing IR radiation and exhibited repeatable response. Moreover, the IV characteristic of the sensor chip was measured when it was surrounded by dry ice for long time to investigate its long term stability under moisture environment. Therefore, the packaging process can become possible to fabricate a CNT based IR sensor array which possesses more stable and reliable performance.