Enhanced signal-to-noise ratio in pristine, suspended carbon nanotube gas sensors

We present hysteresis-free, suspended carbon nanotube gas sensors that have been fabricated with a dry transfer technique. By avoiding process contamination and oxide charge traps, we eliminate the long-term baseline drift associated with charge-trapping that is commonly observed in conventional substrate-bound gas sensors under constant bias conditions. Long-term noise measurements on the suspended devices show that the low-frequency flicker noise attributed to charge trapping is also strongly reduced compared to on-substrate devices. Correspondingly, the average signal-to-noise ratio improves by 9 times compared to the substrate-bound, top-down contacted carbon nanotube gas sensors on a SiO2 substrate. (C) 2014 Elsevier B.V. All rights reserved.