Tunable skewed edges in puckered structures

TL;DR

This paper introduces a new type of edges in puckered honeycomb structures like phosphorene, showing their electronic properties are tunable and can induce a metal-insulator transition, enabling potential field-effect transistor applications.

Contribution

It reveals the existence of skewed edges in puckered structures and demonstrates their tunable electronic properties and potential for device applications.

Findings

Skewed-zigzag edges are semiconducting.

Skewed-armchair edges are metallic.

Electric fields can induce a metal-insulator transition.

Abstract

We propose a new type of edges, arising due to the anisotropy inherent in the puckered structure of a honeycomb system such as in phosphorene. Skewed-zigzag and skewed-armchair nanoribbons are semiconducting and metallic, respectively, in contrast to their normal edge counterparts. Their band structures are tunable, and a metal-insulator transition is induced by an electric field. We predict a field-effect transistor based on the edge states in skewed-armchair nanoribbons, where the edge state is gapped by applying arbitrary small electric field $E_z$. A topological argument is presented, revealing the condition for the emergence of such edge states.