Atomic-scale imaging of few-layer black phosphorus and its reconstructed edge

TL;DR

This study uses advanced electron microscopy to analyze the atomic structure of few-layer black phosphorus, revealing edge reconstructions and providing insights into its stability and potential for nanostructuring.

Contribution

It presents the first atomic-scale imaging of few-layer BP edges and demonstrates layer-dependent resolution, combining experimental TEM imaging with theoretical calculations.

Findings

Reconstructed zigzag edge structures identified

Layer-dependent atomic resolution imaging achieved

Crystalline edges and nanoribbons observed

Abstract

Black phosphorus (BP) has recently emerged as an alternative 2D semiconductor owing to its fascinating electronic properties such as tunable bandgap and high charge carrier mobility. The structural investigation of few-layer BP, such as identification of layer thickness and atomic-scale edge structure, is of great importance to fully understand its electronic and optical properties. Here we report atomic-scale analysis of few-layered BP performed by aberration corrected transmission electron microscopy (TEM). We establish the layer-number-dependent atomic resolution imaging of few-layer BP via TEM imaging and image simulations. The structural modification induced by the electron beam leads to revelation of crystalline edge and formation of BP nanoribbons. Atomic resolution imaging of BP clearly shows the reconstructed zigzag (ZZ) edge structures, which is also corroborated by van der Waals first principles calculations on the edge stability. Our study on the precise identification of BP thickness and atomic-resolution imaging of edge structures will lay the groundwork for investigation of few-layer BP, especially BP in nanostructured forms.