Optimizing Sensor Response in Suspended, Ultra Low Power CNT-FET NO2 Gas Sensors via Bias Tuning

The presented work reports on optimum bias conditions for a carbon nanotube NO
₂
gas sensor and novel insights on the sensing mechanism. When sweeping the source-drain bias V
_ds
(0.1-2.2 V) and gate bias V
_g
(±10 V) the change in conductivity upon gas exposure reaches a maximum at Vg=-10 V and V
_ds
=0.6 V, equivalent to a 70% sensitivity increase compared to a low-bias V
_ds
=0.1 V. Contact barrier thinning by hole doping NO
₂
molecules is proposed as a mechanism for response modulation with gas concentration.