Optimisation of Ion/Ioff and transconductance of germanium based dual metal gate hetero-dielectric TFET

Abstract

This simulation study delves in to the exploration of Tunnel Field Effect Transistors (TFET) with Dual Metal Gate (DMG) hetero-dielectric structure incorporating a Germanium channel using simulations study in TCAD. The device efficiency measures such as current in the off-state (I_off), on-state current (I_on), switching efficiency of the current (I_on/I_off) are observed for the proposed device. The metrics are taken in comparison with the traditional DMG hetero-dielectric MOSFET. The recommended device exhibits a 74.8 % reduction in the Subthreshold Slope (SS) compared to the traditional DMG hetero-dielectric MOSFET. An enhanced I_on/I_off ratio of 4.669 × 10⁸for Ge channel TFET is observed over a conventional DMG MOSFET simulated under same environmental conditions. The performance analysis has been carried out for various channel thickness (t_ch), oxide thickness (t_ox), tunneling lengths (L1:L2) and different gate metal work functions. A detailed RF analysis for hetero dielectrics with HfO₂ near the source area and SiO₂ near the drain area is carried out for DMG Hetero Dielectric TFET. It is evident that positioning the low-k dielectric in close proximity to the drain region leads to the suppression of parasitic capacitances such as C_gd and C_gg. This characteristic enhances its suitability as a superior aspirant for nano digital applications.