Analysis of GeSn-SiGeSn hetero-tunnel FETs

Among the alloys of Group IV semiconductors the Germanium-Tin (GeSn) alloy is particularly interesting as it exhibits a small and direct band gap for a certain range of Sn content. This feature can be exploited for high-performance tunnel FET (TFET) application. The small direct band gap enhances the band-to-band-tunneling (BTBT) rate which results in a high on-current. In order to reduce the off-state leakage, Silicon-Germanium-Tin (SiGeSn) alloys can be used in the drain region of the TFET. Addition of Si to GeSn increases the band gap of the alloy, thus reducing the ambipolar behavior. Therefore, the GeSn/SiGeSn hetero-structure system is a promising candidate for TFET application. In this work, the performance of GeSn/SiGeSn TFETs is studied by combining the empirical pseudopotential method (EPM) with 2D/3D technology-computer-aided-design (TCAD) simulations of realistic geometries.