Anisotropic Wet Etching of WSe₂ and MoS₂ for Twist-Angle Extraction of Heterobilayers

Abstract

We focus on the formation of hexagonal holes in WSe 2 and MoS 2 multilayers by anisotropic wet etching. It is found that anisotropic wet etching occurs for a high H 2 O 2 concentration in an etchant and large thicknesses of WSe 2 and MoS 2 . Furthermore, photoexcited carriers accelerate the anisotropic wet etching of the WSe 2 multilayers. It is found that the oxidation process at the edges of WSe 2 crystals significantly impacts anisotropic wet etching, and photoexcited carriers facilitate the WSe 2 oxidation reaction with H 2 O 2 . We also demonstrate that anisotropic wet etching can be used to determine the twist angle in WSe 2 /MoS 2 heterobilayers. The photoluminescence intensities of the infrared interlayer exciton are proportional to the twist angle in the heterobilayers. These results suggest the potential for exploiting the orientation-dependent phenomena of transition metal dichalcogenides.