A novel gate engineered L-shaped dopingless tunnel field-effect transistor

Recently, dopingless tunnel FET (DL-TFET) has emerged and gathered much attention, for it avoids the physical doping process and provides superior immunity against random dopant fluctuation. Nevertheless, it also suffers from low drive current and severe ambipolar effect. In order to overcome these problems, an L-shaped DL-TFET (LDL-TFET) with the gate engineering technique is proposed in this paper. In this device, the space between the source and the gate electrodes can be further optimized to reduce the tunneling distance, and hence boost the drive current. Also, without much fabrication difficulties, hetero-gate-dielectric (HGD) and tunneling gate (TG) structures can be utilized in the LDL-TFET. Benefiting from the modification of the band energy by HGD and TG, the source-channel tunneling distance is further reduced, while the drain-channel tunneling distance is enlarged. TCAD simulation results show that in comparison with planar DL-TFET (PDL-TFET), LDL-TFET offers better performance in terms of on-current, switch ratio, subthreshold slope, ambipolar current and RF parameters. It indicates that the LDL-TFET is a promising device for low-power RF and digital logic applications.