Partially planar BP3 with high electron mobility as a phosphorene analog

Abstract

Based on first-principles calculations, we propose a two-dimensional α BP₃ crystal in which one quarter of the phosphorus atoms in phosphorene are substituted by boron atoms. Its geometrical structure resembles that of graphene more than that of phosphorene, although phosphorus is present as a major component. It is dynamically stable and energetically much more stable than another allotrope analogous to blue (β) phosphorene. The α BP₃ monolayer is a semiconductor with an indirect band gap (=0.77 eV) within the HSE06 calculation. For the BP₃ bilayer, three stacking patterns are equally stable within 3 meV per atom. The monolayer exhibits a high electron mobility (∼4.6 × 10⁴ cm² V⁻¹ s⁻¹) along the zigzag direction. In the bilayer, the mobility is ∼200 times higher than that of the α phosphorene bilayer. Specifically, it is even higher (∼3.7 × 10⁵ cm² V⁻¹ s⁻¹) and amounts to ∼2500 times in one of the patterns. Therefore, the BP₃ monolayer or bilayer will be useful as an n-type material in nanoelectronics through appropriate doping.