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

摘要

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 degrees, 40 degrees, 80 degrees and 130 degrees 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.