Performance evaluation and analysis for carbon nanotube (CNT) based IR detectors

Abstract

Carbon nanotubes (CNTs) have a potential to be efficient infrared (IR) detection materials due to their unique electronic properties. The ballistic electronic transport property makes the noise equivalent temperature difference smaller compared to other semiconducting materials. In order to explore this potential application, CNT based IR detectors are fabricated by depositing the CNTs on the substrate surface and then aligning them using the Atomic Force Microscopy (AFM) based nanomanipulation system. Normally semicnoductive CNT forms a Schottky barrier with the contact metal. The photogenerated electron-hole pairs within the Schottky barrier are seperated by an external electric field or the built-in field, producing a photocurrent. This paper will focus on the performance evaluation and analysis for the CNT based IR detectors. Experiments were carried out to investigate the photoresponse of single carbon nanotube based IR detectors. Based on the experimental results, the detectivity D* and the quantum efficiency are calculated and analyzed. The MWNT IR detector has a quantum efficiency of 0.313, which is much larger than the reported values of SWNTs. And the SWNT IR detector has a quantum efficiency of 0.01, which is consistent with the reported values. Both MWNT and SWNT show a low detectivity. The analysis shows that the performance of CNT based IR detectors can be further improved by using asymmetric contacts instead of symmetric contacts.