Scalable GaSb/InAs tunnel FETs with non-uniform body thickness

TL;DR

This paper proposes a non-uniform body thickness design for GaSb/InAs tunnel FETs that significantly reduces leakage and enhances ON current, demonstrating high performance at 15nm channels through atomistic quantum transport simulations.

Contribution

It introduces a novel non-uniform body thickness design that improves tunneling FET performance by combining quantum confinement effects with a thick source-channel junction.

Findings

Achieves ballistic ON current of 284A/m at 15nm channel length

Reduces OFF-state leakage by using quantum confinement in thin channels

Demonstrates scalability to sub-10nm channel lengths

Abstract

GaSb/InAs heterojunction tunnel field-effect transistors are strong candidates in building future low-power integrated circuits, as they could provide both steep subthreshold swing and large ON-state current ($I_{\rm{ON}}$). However, at short channel lengths they suffer from large tunneling leakage originating from the small band gap and small effective masses of the InAs channel. As proposed in this article, this problem can be significantly mitigated by reducing the channel thickness meanwhile retaining a thick source-channel tunnel junction, thus forming a design with a non-uniform body thickness. Because of the quantum confinement, the thin InAs channel offers a large band gap and large effective masses, reducing the ambipolar and source-to-drain tunneling leakage at OFF state. The thick GaSb/InAs tunnel junction, instead, offers a low tunnel barrier and small effective masses, allowing a large tunnel probability at ON state. In addition, the confinement induced band discontinuity enhances the tunnel electric field and creates a resonant state, further improving $I_{\rm{ON}}$. Atomistic quantum transport simulations show that ballistic $I_{\rm{ON}}=284$A/m is obtained at 15nm channel length, $I_{\rm{OFF}}=1\times10^{-3}$A/m, and $V_{\rm{DD}}=0.3$V. While with uniform body thickness, the largest achievable $I_{\rm{ON}}$ is only 25A/m. Simulations also indicate that this design is scalable to sub-10nm channel length.