Tunneling and Occupancy Probabilities: How Do They Affect Tunnel-FET Behavior?

In this letter, the occupancy and tunneling probabilities of interband tunneling devices are studied, pointing out the fundamental function of the source Fermi–Dirac distribution. Particularly, the reason for the degraded subthreshold swing, which is typical of devices with highly doped source, is explained, and its relation with the high-energy source Fermi tail is carefully analyzed. Simultaneously, the poor driving capability of Tunnel-FET devices is investigated, highlighting the primary role played by the occupancy functions.