Analysis of InAs Vertical and Lateral Band-to-Band Tunneling Transistors: Leveraging Vertical Tunneling for Improved Performance

TL;DR

This paper demonstrates that InAs TFETs with a heavily doped pocket and optimized vertical tunneling can achieve higher ON current and steeper subthreshold swing, but device thickness and direct tunneling effects are critical factors.

Contribution

It introduces a design strategy leveraging vertical tunneling in InAs TFETs to enhance performance, supported by self-consistent quantum transport simulations.

Findings

Vertical tunneling significantly increases ON current.

A critical device thickness is required for vertical tunneling advantage.

Ultra small devices are affected by source-to-drain tunneling.

Abstract

Using self-consistent quantum transport simulation on realistic devices, we show that InAs band-to-band Tunneling Field Effect Transistors (TFET) with a heavily doped pocket in the gate-source overlap region can offer larger ON current and steeper subthreshold swing as compared to conventional tunneling transistors. This is due to an additional tunneling contribution to current stemming from band overlap along the body thickness. However, a critical thickness is necessary to obtain this advantage derived from 'vertical' tunneling. In addition, in ultra small InAs TFET devices, the subthreshold swing could be severely affected by direct source-to-drain tunneling through the body.