Modulation-doped Gate-Normal Tunnel FET for Improved Turn-on Abruptness

Summary form only given. The tunnel field-effect-transistor (TFET), which is expected to achieve a subthreshold swing (SS) of less than 60mV/dec, is one of the most promising device concepts for enabling supply power scaling to below 0.5 V. Encouraging experimental heterojunction-TFETs results with MOSFET-like ON-currents have been reported recently [1]-[2]. However, the SS increased in both high and low drain current regimes, resulting in a U-shaped relationship where a good SS was preserved only at a moderate drain current [1]-[2]. A characteristic behavior for TFETs is a SS increase with drain current, where the lowest achievable SS ideally should occur when tunneling begins. Possible explanations for the non-abrupt turn-on at low drain current regime include band edge abruptness, trap states that trigger trap-assisted tunneling, non-uniformity of the device system, and non-optimal electrostatic control of the device structure [3]. In this work, we focus on improving electrostatic control for gate-normal-TFETs to achieve better turn-on abruptness.