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

• We present a suspended ultraclean device architecture for individual carbon nanotube gas sensors.
• We compare the performance of suspended and non-suspended carbon nanotube gas sensors.
• Suspended devices show a strong reduction in charge noise compared to non-suspended devices.
• The signal to noise ratio is enhanced significantly (9 times) for suspended devices.

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.