Simulated scanning tunneling microscopy images of few-layer phosphorus capped by graphene and hexagonal boron nitride monolayers

Abstract

Elemental phosphorous is believed to have several stable allotropes that are energetically nearly degenerate, but chemically reactive. These structures may be capped by monolayers of hexagonal boron nitride $(h\ensuremath{-}\mathrm{BN})$ or graphene to prevent chemical degradation under ambient conditions. We perform ab initio density functional calculations to simulate scanning tunneling microscopy (STM) images of different layered allotropes of phosphorus and study the effect of the capping layers on these images. At scanning energies within its intrinsic conduction gap, protective monolayers of insulating $h\ensuremath{-}\mathrm{BN}$ allow to distinguish between the different structural phases of phosphorus underneath due to the electronic hybridization with orbitals from the upmost phosphorus atoms: $h\ensuremath{-}\mathrm{BN}$ capping monolayers thus provide a promising route to tell few-layer phosphorus allotropes from one another with local probes.