Hexagonal boron phosphide monolayer exfoliation induced by arsenic incorporation in the BP (1 1 1) surface: A DFT study

Abstract

Density functional theory (DFT) calculations have been performed to investigate adsorption and incorporation of arsenic on the boron phosphide (111) surface. We considered different arsenic coverages. Dimers (1/2 ML), trimers (¾ ML), and atomic wires (1 ML) are formed upon increasing As coverage. However, at full monolayer, the most relevant result is the hexagonal boron phosphide (h-BP) monolayer formation, a 2D graphene-like structure. The h-BP monolayer phonon dispersion shows only positive frequencies indicating dynamical stability. At the same time, this suggests the possible h-BP monolayer exfoliation (desorption energy of only 0.26 eV/1x1) because it is weakly attached to the substrate by van der Waals interactions, as demonstrated by the non-covalent interaction index analysis. Electronic band structures indicate that this 2D layer may support direct transitions, making it useful for applications in electronic devices. The density of states and projected density of states complement the electronic properties analysis. We encourage the experimental realization of h-BP by As incorporation on BP surfaces.