A Non-Quasi-Static Model for Tunneling FETs Based on the Relaxation Time Approximation

The models for tunneling field-effect-transistors (TFETs) reported up to date mainly used a quasi-static (QS) method to simulate the dc current-voltage (I-V) and capacitance-voltage (C-V) characteristics. The ignoring of the finite charging time of channel carriers makes the QS models problematic for the transient and ac simulations. In this paper, the relaxation time approximation (RTA) is adopted for the first time to develop a non-quasi-static (NQS) model for TFETs taking the effects of the carrier charging time into account and good agreements have been obtained between the model results and the numerical simulations. The proposed NQS model can give accurate prediction of not only the transient current under different signal changing range and rate, but also high-frequency capacitance. Moreover, the new NQS model is deduced based on the existing I-V and C-V model. This makes the new model can be easily incorporated with the existing I-V and C-V model for comprehensive description of TFET-based circuits.