Polarized Raman spectra of phosphorene in edge and top view measuring configurations

Abstract

We demonstrate the anisotropic features of the A_1g, B_2g and A_2g vibrational Raman modes of phosphorene by performing for the first time a comparison of two orthogonal polarized Raman scattering studies in edge and top view measuring configurations. Despite the orthogonality between the vibration modes of A_1g and A_2g, they exhibit intense and very weak Raman intensities under light polarized along and transverse to the armchair edge, respectively, while the B_2g mode is virtually non-existent. The B_2g mode significantly appears only in the top view configuration. The studies performed under different intensities of excited light in the top view configuration are detailed for the sample rotated at 0°, 40°, 80° and 130° about the incident laser beam. The studies reveal a quadratic opposite behavior of the A_2g and B_2g modes and an unusual angle dependence of the A_1g vibrational mode. An unexpected behavior of the A_2g Raman mode at higher intensities, which still persists for the A_1g mode, is shown. The anomalous behavior of the A_1g mode from the edge and top view and the A_2g mode in the top view configuration is explained in terms of the layer stacking structures of phosphorene.