Fabrication and experimental testing of individual multi-walled carbon nanotube (CNT) based infrared sensors

Abstract

Carbon nanotubes (CNTs) have a potential to be efficient infrared (IR) detection materials due to their unique electronic properties. Since carbon nanotube films lose special properties of CNTs and increase noises, a single CNT is preferred for building infrared sensors. Although some experimental progress toward individual single-walled carbon nanotube (SWNT) based IR sensor has been reported, several difficulties hindered the further development of individual CNT based IR sensors. Firstly, there is no a reliable and efficient way to reproducibly fabricate individual CNT based sensors up to now. In this paper, an automated dielectrophoresis deposition system is used to deposit CNTs around the electrodes, and then an Atomic Force Microscopy based nanomanipulation system is used to position an individual CNT onto the electrodes. Since this process is controllable and reliable, it becomes possible to fabricate an individual CNT based sensor array, which is difficult to make with other fabrication method. Secondly, since it is very difficult to control the diameter of the SWNTs during production process, it is difficult to get a SWNT based infrared sensor with expected bandgap. To solve this problem, the electronic breakdown technique is used to tune the semiconducting properties of a single multi-walled carbon nanotube (MWNT). The diameter of a single MWNT can be modified by electrical breakdown of outer layer of nanotube walls. Thirdly, SWNT has a low quantum efficiency (~ 0.02-0.1) due to its thin diameter and short absorption depth. In this paper, a single MWNT based infrared sensor is fabricated and tested. It shows a higher quantum efficiency (∼ 0.3) than the SWNT based infrared sensors. © 2007 IEEE.