Universal model for electron thermal-field emission from two-dimensional semimetals

TL;DR

This paper develops a universal theory for electron thermal-field emission from various 2D semimetals, revealing that their emission characteristics are indistinguishable regardless of band topology, and extends classical thermionic emission laws to 2D materials.

Contribution

It introduces a universal scaling relation for electron emission in 2D semimetals, applicable across different topological classes, and clarifies the lack of topological signatures in emission behavior.

Findings

Universal emission scaling law for 2D semimetals.

Band topology does not affect electron emission characteristics.

Provides theoretical basis for 2D-material-based vacuum nanoelectronics.

Abstract

We present the theory of out-of-plane (or vertical) electron thermal-field emission from 2D semimetals. We show that the current-voltage-temperature characteristic is well-captured by a universal scaling relation applicable for broad classes of 2D semimetals, including graphene and its few-layer, nodal point semimetal, Dirac semimetal at the verge of topological phase transition and nodal line semimetal. Here an important consequence of the universal emission behavior is revealed: in contrast to the common expectation that band topology shall manifest differently in the physical observables, band topologies in two spatial dimension are indistinguishable from each others and bear no special signature in the electron emission characteristics. Our findings represent the quantum extension of the universal semiclassical thermionic emission scaling law in 2D materials, and provide the theoretical foundations for the understanding of electron emission from cathode and charge interface transport for the design of 2D-material-based vacuum nanoelectronics.