Overcoming Boltzmann's Tyranny in a Transistor via the Topological Quantum Field Effect

TL;DR

This paper introduces the Topological Quantum Field Effect transistor (TQFET), which leverages topological phase transitions and Rashba spin-orbit interaction to significantly reduce sub-threshold swing beyond Boltzmann's limit, enabling more efficient low-power transistors.

Contribution

It presents a novel theoretical framework showing how topological phase transitions and Rashba interaction can lower sub-threshold swing without fundamental limits.

Findings

Rashba interaction can reduce sub-threshold swing by over 25%

Topological phase transition enables conduction in the proposed transistor

No fundamental lower bound on sub-threshold swing in this system

Abstract

The sub-threshold swing is the fundamental critical parameter determining the operation of a transistor in low-power applications such as switches. It determines the fraction of dissipation due to the gate capacitance used for turning the device on and off, and in a conventional transistor it is limited by Boltzmann's tyranny to kTln(10)/q, or 60 mV per decade. Here, we demonstrate that the sub-threshold swing of a topological transistor, in which conduction is enabled by a topological phase transition via electric field switching, can be sizably reduced in a non-interacting system by modulating the Rashba spin-orbit interaction via a top-gate electric field. We refer to this as the Topological Quantum Field Effect and to the transistor as a Topological Quantum Field Effect transistor (TQFET). By developing a general theoretical framework for quantum spin Hall materials with honeycomb lattices we explicitly show that the Rashba interaction can reduce the sub-threshold swing by more than 25% compared to Boltzmann's limit in currently available materials, but without any fundamental lower bound, a discovery that can guide future materials design and steer the engineering of topological quantum devices.