Probing the anisotropic behaviors of black phosphorus by transmission electron microscope, angular-dependent Raman spectra and electronic transports measurements

TL;DR

This study investigates the anisotropic properties of black phosphorus using transmission electron microscopy, Raman spectroscopy, and electronic transport measurements, revealing how crystallographic orientation influences its optical and electronic behaviors.

Contribution

It provides direct experimental evidence linking crystallographic directions to anisotropic optical and electronic properties of black phosphorus, advancing understanding of its directional behaviors.

Findings

Maximum Raman A2g mode intensity along zigzag direction

Superior conductance and mobility in zigzag orientation

Enhanced anisotropic Raman response due to lattice extension along armchair direction

Abstract

In this work, we correlated the angular dependence of the Raman response of black phosphorus to its crystallographic orientation by using transmission electron microscopy and Raman spectroscopy. It was found that the intensity of the A2g mode reached a maximum when the polarization direction of the incident light was parallel to the zigzag crystallographic orientation. Notably, it was further confirmed that the zigzag crystallographic direction exhibited superior conductance and carrier mobility. Because of the lattice extension along the armchair direction, an intensification of the anisotropic Raman response was observed. This work provides direct evidence of the correlation between anisotropic properties and crystallographic direction and represents a turning point in the discussion of the angular-dependent electronic properties of black phosphorus.