Absorption dichroism of monolayer 1T′-MoTe ₂ in visible range

Abstract

Among various transition metal dichalcogenides, MoTe 2 has drawn attention due to its capability of robust phase engineering between semiconducting (2H) and semi-metallic distorted octahedral (1T′) phase. In particular, 1T′-MoTe 2 has been predicted to have intriguing physics such as quantum spin Hall insulator, large magnetoresistance, and superconductivity. Recent progress showed weak antilocalization behavior in 1T′-MoTe 2 which is the one of representative characteristics in topological insulator. Here, we grow centimeter-scale monolayer 1T′-MoTe 2 on SiO 2 /Si substrate via chemical vapordeposition and demonstrate dichroism in visible range. Ribbon-like 1T′-MoTe 2 flakes were initially nucleated randomly on SiO 2 substrate and at a later stage merged to form a continuous monolayer film over the entire substrate. Each flake revealed one dimensional Mo-Mo dimerization feature and anisotropic absorption behavior in visible range (400-600 nm). This allowed us to detect the grain boundary due to stark contrast difference among flakes in different orientations.

Electronic and Optoelectronic Applications Based on 2D Novel Anisotropic Transition Metal Dichalcogenides

“…1T′ MoTe 2 (or Td WTe 2 ) showed strong anisotropic properties, and exhibits anisotropic absorption behavior in the visible range. Figure f shows the polarizing optical image with enhanced contrast by inserting both a polarizer and analyzer crossed by nearly 85° . This phenomenon can be ascribed to anisotropic absorption.…”

“…For 2D tellurides, specifically MoTe 2 and WTe 2 , the development of anisotropy is complicated due to their rich phase diagrams. MoTe 2 (WTe 2 ) possesses semiconducting (2H) and semimetal distorted octahedron (1T′ or Td) phases and exhibits anisotropic absorption behavior in the visible range . For MoTe 2 and WTe 2 , the strong anisotropic properties lead to a semimetal phase.…”

“…g) Under perfectly crossed polarizer–analyzer (P–A) setup, nothing can be seen. Reproduced with permission . Copyright 2014, IOP Publishing.…”

“…Most MTe 2 ‐based FETs have been reported to possess a carrier mobility of 1–68 cm 2 V −1 s −1 and large on/off ratios of 10 4 –10 6 . Pradhan et al reported hole‐doped MoTe 2 field‐effect transistors ( Figure a) with a saturated carrier mobility of up to 20 cm 2 V −1 s −1 under a suitable bias at room temperature.…”

Polarization-Dependent Optical Properties and Optoelectronic Devices of 2D Materials

“…Another work presents the contrast difference of reflectance measurements, where the contrast is high at the wavelength below 450 nm. In the range of 450–650 nm, the contrast shows the maximum intensity at zero angle (along the main axis of the flake), and a clear symmetry can be observed exhibiting a repeated period of 180° [ 123 ].…”