# Surface buckling of phosphorene materials: determination, origin and influence on electronic structure

## TL;DR

This study uses advanced microscopy and calculations to reveal significant surface buckling in phosphorene materials, linking it to surface vacancies and intrinsic hole doping, which impacts their electronic properties.

## Contribution

It provides the first detailed measurement of surface buckling in phosphorene and links it to surface vacancies and doping effects using combined experimental and theoretical methods.

## Key findings

- Surface buckling of 0.22 Å in black phosphorus
- Surface buckling of 0.30 Å in exfoliated phosphorene
- Surface vacancies contribute to buckling and doping

## Abstract

The surface structure of phosphorene crystals materials is determined using surface sensitive dynamical micro-spot low energy electron diffraction ({\mu}LEED) analysis using a high spatial resolution low energy electron microscopy (LEEM) system. Samples of (\textit{i}) crystalline cleaved black phosphorus (BP) at 300 K and (\textit{ii}) exfoliated few-layer phosphorene (FLP) of about 10 nm thicknes, which were annealed at 573 K in vacuum were studied. In both samples, a significant surface buckling of 0.22 {\AA} and 0.30 {\AA}, respectively, is measured, which is one order of magnitude larger than previously reported. Using first principle calculations, the presence of surface vacancies is attributed not only to the surface buckling in BP and FLP, but also the previously reported intrinsic hole doping of phosphorene materials.