Electrically Tunable Quasi-Flat Bands, Conductance and Field Effect Transistor in Phosphorene

TL;DR

This paper studies the electric properties of phosphorene nanoribbons, revealing controllable quasi-flat edge bands that enable a field-effect transistor, advancing nanoelectronics with tunable electronic features.

Contribution

It introduces the concept of electrically tunable quasi-flat bands in phosphorene nanoribbons and demonstrates their potential for field-effect transistors.

Findings

Quasi-flat edge bands are controllable by in-plane electric fields.

Conductance can be switched off at a critical electric field.

Critical electric field inversely proportional to nanoribbon width.

Abstract

Phosphorene, a honeycomb structure of black phosphorus, was isolated recently. We investigate electric properties of phosphorene nanoribbons based on the tight-binding model. A prominent feature is the presence of quasi-flat edge bands entirely detached from the bulk band. We explore the mechanism of the emergence of the quasi-flat bands analytically and numerically from the flat bands well known in graphene by a continuous deformation of a honeycomb lattice. The quasi-flat bands can be controlled by applying in-plane electric field perpendicular to the ribbon direction. The conductance is switched off above a critical electric field, which acts as a field-effect transistor. The critical electric field is anti-proportional to the width of a nanoribbon. This results will pave a way toward nanoelectronics based on phosphorene.