Phase coexistence and metal-insulator transition in few-layer phosphorene: A computational study

TL;DR

This computational study identifies new stable phases of layered phosphorus, revealing their potential for metal-insulator transitions and phase coexistence, which could enable novel heterostructure applications.

Contribution

It predicts two new stable phosphorus phases and demonstrates their tunable electronic properties via strain and layer number, expanding the understanding of phosphorene's phase behavior.

Findings

Identified $\gamma$-P and $\delta$-P as stable phosphorus phases.

Showed metal-insulator transition in some allotropes due to strain or layer change.

Proposed phase coexistence as a method for heterostructure design.

Abstract

Based on {\em ab initio} density functional calculations, we propose $\gamma$-P and $\delta$-P as two additional stable structural phases of layered phosphorus besides the layered $\alpha$-P (black) and $\beta$-P (blue) phosphorus allotropes. Monolayers of some of these allotropes have a wide band gap, whereas others, including $\gamma$-P, show a metal-insulator transition caused by in-layer strain or changing the number of layers. An unforeseen benefit is the possibility to connect different structural phases at no energy cost. This becomes particularly valuable in assembling heterostructures with well-defined metallic and semiconducting regions in one contiguous layer.