Ultra-high sensitive gas sensor based on graphene/carbon nanotube barristor

We have investigated switching characteristics in graphene/semiconducting single-walled carbon nanotube (SWCNT) junction device, so-called graphene/SWCNT barristor. We modulated the Schottky barrier between the graphene and the carbon nanotube by using top and bottom gate electrodes, and achieved on-off ratio of 10⁸ and the subthreshold swing of 74 mV/dec with high current density. In addition, we demonstrated the potential of our device as a NO₂/NH₃ gas sensor. Graphene/SWCNT barristor showed the 10⁷ % of sensitivity for the 100 ppm NO₂ gas, and 10⁵ % of sensitivity for the 100 ppm NH₃ gas. Also, our device is sensitive enough to detect NO₂ gas down to 25 ppb concentration with 400 % sensitivity.