Impact of geometry and non-idealities on electron 'optics' based graphene p-n junction devices

TL;DR

This paper explores how geometry and non-idealities affect the performance of graphene p-n junction devices that manipulate electron flow like light, highlighting the importance of device design and edge quality.

Contribution

It provides a detailed analysis of how geometry and edge scattering influence electron optics in graphene transistors, supported by simulations and experimental data.

Findings

Edge roughness significantly impacts transport gap quality.

Geometry critically affects electron angular resolution.

Reducing edge scattering improves device performance.

Abstract

We articulate the challenges and opportunities of unconventional devices using the photon like flow of electrons in graphene, such as Graphene Klein Tunnel (GKT) transistors. The underlying physics is the employment of momentum rather than energy filtering to engineer a gate tunable transport gap in a 2D Dirac cone bandstructure. In the ballistic limit, we get a clean tunable gap that implies subthermal switching voltages below the Boltzmann limit, while maintaining a high saturating current in the output characteristic. In realistic structures, detailed numerical simulations and experiments show that momentum scattering, especially from the edges, bleeds leakage paths into the transport gap and turns it into a pseudogap. We quantify the importance of reducing edge roughness and overall geometry on the low-bias transfer characteristics of GKT transistors and benchmark against experimental data. We find that geometry plays a critical role in determining the performance of electron optics based devices that utilize angular resolution of electrons.