Structural Modification of Doped Tunnel Field Effect Transistor for Enhanced Conduction Current and Lower Subthreshold Swing

Abstract

The material solubility in the source region and abrupt source/channel junction profile are the major concern which is responsible for the improvement of the electrical characteristics of conventional physical doped tunnel field effect transistor (PD-TFET). For this, an additional negatively polarised electrode is mounted in P+ (source) – N (channel) – N+ (drain) structure over the source region to overcome material solubility. This improves the electrical characteristics of the device. Along with this, we have implanted a low workfunction metal layer (ML) in the oxide layer under the gate electrode for creating more abruptness at the junction to improve the subthreshold swing (SS) of the device. Thus, the proposed concept improves the DC/RF performance of the doped TFET device. Further to this, the optimization of metal layer workfunction and misalignment of metal layer in TFET have been performed to get optimum device characteristics. In addition to this, for the suppression of ambipolar behaviour, gate electrode is shorted from the drain side. Due to short length of gate electrode tunneling barrier width at the drain/channel junction increases, hence the tunneling probability decreases which reduces the ambipolar current to parasitic current. Shortening of gate electrode also improves the RF performance.