Carbon Nanotube Based Infrared Detector Array

As a promising nanomaterial, carbon nanotube (CNT) has been studied for infrared sensing with their unique properties such as wide range of band gaps and reduced carrier scattering. However, due to the traditional inefficient and unreliable fabrication processes, the research of CNT based infrared sensors remained on the single pixel study, which significantly limited the further investigation and application of CNTs in infrared sensing. In this study, a reliable and efficient nanomanufacturing process was used to build CNT based infrared detector array. A pixel is fabricated by assembling a single CNT or a small bundle of CNTs onto a pair of microelectrodes to form connections. The assembly process utilizes the dielectrophoresis deposition method to attract CNTs around the microelectrodes and the Atomic Force Microscope (AFM) nanomanipulation system to position CNTs. Since the process is reliable and controllable, it enables the possibility to fabricate CNT based infrared detector arrays. A three-pixel CNT based infrared detector array with a 10 mum pixel pitch was fabricated in this paper. The electronic and photonic properties of each pixel are tested and characterized. Experimental results have shown that the three pixels have small thermal crosstalk between adjacent pixels, which is an important factor limiting the pixel pitch of infrared focal plane arrays (IRFPAs). Since the traditional IRFPAs have a pixel pitch in the range of 25-50 mum or even larger, their resolutions are normally very low. The small pixel pitch of the developed CNT detector array makes it possible to fabricate high resolution IRFPAs.