On the Subthreshold Performance of Topological Insulator Field Effect Transistors under Momentum Relaxation Scattering

The Rashba-facilitated topological quantum field-effect (TQFE) in monolayer 2D-Xenes provides interesting play-ground to actuate subthermionic operation in 2D topological insulator FETs (TI-FETs). Delving into the physics of the quantum field-effect transition between the non-trivial topological phase and the trivial band insulator phase is required to develop effective device design strategies. Our investigation of viable device structures underlines the challenges that one needs to overcome in order to fully tap the potential of TQFE in surpassing the Boltzmann's limit on the subthreshold swing (SS). Based on our thorough investigation of intricate band translation physics associated to the topological phase transition, we successfully demonstrate a gating method with additional design considerations that beats the thermionic limit, but at the cost of sacrificing the dissipationless ON-state conduction. We then proceed with the study of the effect of momentum relaxation on our proposed TI-FET performance in an experimentally relevant regime in the presence of scatterers. Our work thus underlines the operational criteria and trade-offs involved for building TI-FETs that can overcome the Boltzmann's tyranny.