Three-terminal CNTs gas sensor for N2 detection

A novel three-terminal gas sensor was fulfilled by utilizing the vertically aligned carbon nanotubes (CNTs) mat. Carbon nanotubes were synthesized by thermal chemical vapor deposition (thermal CVD) at 700 °C under C2H2 gas flow rate of 30 sccm. Upon exposure to a with and without N2 environment at the room temperature of 25 °C, the electrical resistance of as-made devices was found to increase and to return back, respectively. Compared to a low bias one, the sensitivity increased when applying a high source drain bias voltage. Furthermore, the device became more sensitive for N2 detection by applying a negative gate voltage. It was concluded that the alteration of free holes concentration in the CNTs mat played the major mechanism for the N2 gas detection.