Anomalous polarization dependence of Raman scattering and crystallographic orientation of black phosphorus

Abstract

We investigated polarization dependence of the Raman modes in black phosphorus (BP) using five different excitation wavelengths. The crystallographic orientation was determined by comparing polarized optical microscopy with high-resolution transmission electron microscopy analysis. In polarized Raman spectroscopy, the B2g mode shows the same polarization dependence regardless of the excitation wavelength or the sample thickness. On the other hand, the Ag(1) and Ag(2) modes show a peculiar polarization behavior that depends on the excitation wavelength and the sample thickness. The thickness dependence can be explained by considering the anisotropic interference effect due to the birefringence and dichroism of the BP crystal, but the wavelength dependence cannot be explained. We propose a simple and fail-proof procedure to determine the orientation of a BP crystal by combining polarized Raman scattering with polarized optical microscopy.

Anomalous in-plane anisotropic Raman response of monoclinic semimetal 1 T´-MoTe 2

“…However, in 5-layer and bulk 1 T´-MoTe 2 , the number of detected modes increases. Given the same layer number, the number of detected modes in 1 T´-MoTe 2 is greater than that in 2H-MoTe 2 , reflecting the lower crystal symmetry of the 1 T´ phase compared with the 2 H phase 31 .…”

Polarized Raman scattering on single crystals of rare earth orthochromite RCrO3 (R = La, Pr, Nd, and Sm)

“…Raman spectroscopy allows to probe the vibrational energy levels from an inelastic process of light scattering . It is a well‐known technique for probing the structural transitions and allows in some cases to investigate local structural changes.…”

Thermal sublimation: a scalable and controllable thinning method for the fabrication of few-layer black phosphorus

“…Thus identifying the crystallographic orientations of BP and Si (100) becomes a perquisite for further thickness profiling to be discussed in following session. According to previous reports 36,38 minimum Raman intensities at orthogonal directions. Thus, in this work, we rotated samples A and C to have maximum A 1 g and minimum A 2 g Raman intensities and kept their positions while performing isothermal joule heating in heating stage.…”

“…The 441.6 nm incident laser beam was polarized, and an analyzer was placed in parallel configuration before the entrance of spectrometer in the same manner like previous study 36,37,38 . BP samples were placed on a rotation stage and rotated 180 • about the microscope optical axis in 12 steps (15 • /step).…”