Effect of varying gate distance on the threshold voltage shift in carbon nanotube field effect transistor gas sensors

Suspended individual carbon nanotubes show great promise in use as gas sensors, as they are not only highly sensitive and selective, but can be operated at a few μW of power consumption. This work reports on a novel architecture and process flow to reduce the voltage range needed for a full sensor characterization to the values given by modern technology. The developed fast and flexible fabrication run yields CNTFET devices with varying gate distances, improving gate coupling up to 25 times to previous own studies. Devices with long gate distances (dg=1.84μm) show a 3.2-times improved signal to noise ratio (voltage shift upon gas adsorption over signal variation) when compared to short gate distance devices (dg=0.24μm). [Display omitted] •Optimal gate distance in CNTFET gas sensor is trade-off between signal & gate coupling.•For short gate distance devices 1V is enough for a full gate sweep characterization.•No correlation could be observed between signal variation and gate distance.