Epitaxial growth of a buckled BiP monolayer on Bi(111)

We report the scanning tunnelling microscopy (STM) study of the epitaxial growth of a blue phosphorene-like BiP monolayer on Bi(111). It is found that, at low coverages, the small islands of the BiP monolayer exhibit tilted tops. With increasing coverage, the extended domains of the BiP monolayer reveal a negligible slope gradient. High-resolution STM images reveal that the BiP monolayer adopts the lattice registration growth mode, i.e., having the same lattice constant as that of Bi(111). The scanning tunnelling spectra (STS) demonstrate the semi-metallic characteristics of the buckled BiP monolayer. Density functional theory (DFT) calculations reveal that the BiP monolayer has a blue phosphorene-like structure with a buckling amplitude of 1.0 Å. Furthermore, the spin-orbit coupling (SOC) interaction in the BiP monolayer leads to the emergence of a Dirac point near the Fermi level. This unique electronic property shows potential for applications in spintronics and electronic devices.