Calculation of OFF-Current of Tunnel FETs based on Subthreshold Swing: A New Approach

The field-effect-transistors (FETs) working on band-to-band tunneling mechanism provide better switching characteristics than field-effect-transistors working on thermionic emission. In this regard, tunnel FETs (TFETs) are found more promising device among FETs working on band-to-band tunneling mechanism. However, TFETs have ambipolar behavior which is not present in the FETs working on thermionic mechanism and due to this OFF-current of TFETs depends on metal-gate workfunction. Thus, to make OFF-current independent of metal gate workfunction the new approach is proposed to calculate the OFF-current which is also independent of ambipolar behavior of TFETs. The proposed approach is based on the subthreshold-swing (SS) of the device and it is validated by the transfer characteristics of experimental TFETs taken in this work to calculate the subthreshold-swing. The calculated OFF-current is found in same order to the earlier reported data in the reports. The comparison results suggest that the approach is valid and encouraging to replace the existing approaches.