Table 1. Comparison of the threshold gate voltages Vth1, Vth2, and their difference ΔVth = Vth2 − Vth1 under different environmental conditions, where Vth1 and Vth2 are the gate voltages at which the drain–source current was Ids = 1 nA in the forward (positive direction) and backward (negative direction) sweep of the Vg, respectively.
| Vth1 | Vth2 | ΔVth | |
|---|---|---|---|
| vacuum | −8.5 | −6.1 | 2.4 |
| N2 | −5.0 | 0.9 | 5.9 |
| O2 | −8.9 | −0.5 | 8.4 |
| air (RH = 18%) | −11.1 | 6.5 | 17.6 |
| N2 (RH = 80%) | −22.0 | 6.8 | 28.8 |
ΔVth is used as a measure of the hysteresis. The effect of hole (electron) trapping can be discussed considering the shift in Vth1 (Vth2) as described in the text.