Pulsed gate sweep strategies for hysteresis reduction in carbon nanotube transistors for low concentration NO2 gas detection

Carbon-nanotube-based field effect transistors (CNFETs) have been employed as highly sensitive chemical sensors. Often used as the sensor output signal, the gate threshold voltage (Vth) is subject to concentration-dependent shifts upon exposure to target analytes. However, an unambiguous determination of the intrinsic Vth is usually hampered by substantial hysteresis in CNFET gate characteristics. In this study we show that short gate voltage (Vgd) pulses can be used for hysteresis reduction in CNFETs as chemical sensors, in particular for NO2 detection. In the pulsed operation regime, even small shifts of Vth upon sub-ppm NO2 exposure remain resolvable. Furthermore, the hysteretic behaviour is systematically investigated by varying the pulse waveforms and timing parameters. Finally, we use an adapted hysteresis model for pulsed Vgd and employ it to discuss the measurement data.