Influence of Carrier-Carrier Interactions on the Sub-threshold Swing of Band-to-Band Tunnelling Transistors

TL;DR

This paper investigates how carrier-carrier interactions, especially Auger processes, negatively impact the sub-threshold swing of band-to-band tunnelling transistors, explaining why they often don't reach ideal low-power switching performance.

Contribution

It provides first-principles quantum transport simulations demonstrating the role of carrier-carrier scattering in degrading TFET performance, confirming Auger processes as a key factor.

Findings

Carrier-carrier scattering increases OFF-state current

Auger processes partly cause SS degradation

Simulations confirm impact on sub-threshold behavior

Abstract

Band-to-band tunnelling field-effect transistors (TFETs) have long been considered as promising candidates for future low-power logic applications. However, fabricated TFETs rarely reach sub-60 mV/dec sub-threshold swings (SS) at room temperature. Previous theoretical studies identified Auger processes as possible mechanisms for the observed degradation of SS. Through first-principles quantum transport simulations incorporating carrier-carrier interactions within the Non-equilibrium Green's Function formalism and self-consistent GW approximation, we confirm here that Auger processes are indeed at least partly responsible for the poor performance of TFETs. Using a carbon nanotube TFET as testbed, we show that carrier-carrier scattering alone significantly increases the OFF-state current of these devices, thus worsening their sub-threshold behavior.