Anisotropic Wet\nEtching of WSe₂ and MoS₂ for Twist-Angle Extraction\nof Heterobilayers

Abstract

We focus on the formation of hexagonal\nholes in WSe₂ and MoS₂ multilayers by anisotropic\nwet etching.\nIt is\nfound that anisotropic wet etching occurs for a high H₂O₂ concentration in an etchant and large thicknesses of\nWSe₂ and MoS₂. Furthermore, photoexcited carriers\naccelerate the anisotropic wet etching of the WSe₂ multilayers.\nIt is found that the oxidation process at the edges of WSe₂ crystals significantly impacts anisotropic wet etching, and photoexcited\ncarriers facilitate the WSe₂ oxidation reaction with H₂O₂. We also demonstrate that anisotropic wet etching\ncan be used to determine the twist angle in WSe₂/MoS₂ heterobilayers. The photoluminescence intensities of the\ninfrared interlayer exciton are proportional to the twist angle in\nthe heterobilayers. These results suggest the potential for exploiting\nthe orientation-dependent phenomena of transition metal dichalcogenides.