A Systematic Investigation of Dual Material Gate TFET for Improved Performance

Abstract

This study explores the influence of different metal gate combinations on the performance of dual-metal gate TFETs (DMG-TFET). The ON-state current in a TFET depends on band-to-band tunneling (BTBT) across the junction between the source and channel regions. Therefore, it is crucial to select a tunnel gate material with an appropriate work function to optimize the devices’ overall performance. The present work explores the effect of dual metal gates having different work functions on tunnel barrier width of TFET. In this work, three distinct Double Gate TFET structures; Double Gate (DG) TFET, Dual Metal Gate (DMG) TFET, and Dual Metal Gate Hetero-Dielectric (DMG-HD) TFET are designed using TCAD device simulator. The proposed device (DMG-HD) TFET is benchmarked by considering various performance metrics such as ON-state current I_ON, OFF-state current I_OFF, ON-to-OFF current ratio I_ON /I_OFF, and sub-threshold slope (SS). This study also highlights the key finding of optimizing the length of dual metals and the work functions of metal gates (M-1) and (M-2) in TFETs. The results show that the proposed device (DMG-HD TFET) gives improved performance compared to the other two devices. The proposed TFET structure improves the ON-current by two orders (10⁻⁵ to 10⁻³ (A/µm)), ION /IOFF ratio by three orders (10⁹ to 10¹² (A/µm)) and sub-threshold swing (SS) by 23.82% compared to the conventional TFET device.