Influence of Hetero-Gate Dielectrics on Short-Channel Effects in Scaled Tunnel Field-Effect Transistors

Abstract In this study, we examined the influence of using hetero-gate dielectrics (HGDs) on the short-channel effects (SCEs) in scaled tunnel field-effect transistors (TFETs). For bulk TFETs, the short-channel performance is not influenced by the HGD engineering because the SCEs are caused by the tunneling at the region with negligible gate control. However, the use of the HGD increases the SCEs in double-gate TFETs because the HGD reduces the gate control on the channel. When the HGD optimized in term of on-current is used, the channel of HGD-TFETs is about 10-nm longer than that of uniform-gate dielectric TFETs to obtain similar SCEs. The SCEs in HGD-TFETs can be improved by locating the drain-side heterojunction toward the drain and/or increasing the ratio of low- and high-k equivalent oxide thicknesses. Due to the trend of scaling transistors, an appropriate design of HGD to minimize the SCEs in scaled HGD-TFETs is also crucial.