Linear Dichroism and Nondestructive Crystalline Identification of Anisotropic Semimetal Few-Layer MoTe2.

Abstract

Semimetal 1T' MoTe2 crystals have attracted tremendous attention owing to their anisotropic optical properties, Weyl semimetal, phase transition, and so on. However, the complex refractive indices (n-ik) of the anisotropic semimetal 1T' MoTe2 still are not revealed yet, which is important to applications such as polarized wide spectrum detectors, polarized surface plasmonics, and nonlinear optics. Here, the linear dichroism of as-grown trilayer 1T' MoTe2 single crystals is investigated. Trilayer 1T' MoTe2 shows obvious anisotropic optical absorption due to the intraband transition of dz 2 orbits for Mo atoms and px orbits for Te atoms. The anisotropic complex refractive indices of few-layer 1T' MoTe2 are experimentally obtained for the first time by using the Pinier equation analysis. Based on the linear dichroism of 1T' MoTe2 , angle-resolved polarized optical microscopy is developed to visualize the grain boundary and identify the crystal orientation of 1T' MoTe2 crystals, which is also an excellent tool toward the investigation of the optical absorption properties in the visible range for anisotropic 2D transition metal chalcogenides. This work provides a universal and nondestructive method to identify the crystal orientation of anisotropic 2D materials, which opens up an opportunity to investigate the optical application of anisotropic semimetal 2D materials.