Stress-guided anisotropic etching of MoS2 nanostructure with spatial control over edge structure and morphology

Abstract

The on-demand patterning of two-dimensional transition metal dichalcogenides (TMDs) with tailored edges are of great importance in their usages in electronic and optoelectronic applications, but remain technically challenging. Herein, we developed a stress-guided anisotropic etching strategy that can produce large-area and well-ordered MoS₂ nanostructures (e.g., nano-ribbons and nano-squares) in a template-free fashion. By creating uniaxially cumulative stress followed by selective thermal etching, the MoS₂ monolayers were statistically etched into ribbon-like structures, the width of which can be manifested and inversely proportional to the applied stress magnitude. In addition, these newly etched edges are found to be macroscopically straight or serrated ones, but predominantly Mo-zigzag terminated and remarkably enhanced the photoluminescence by a factor of ∼8.0. The priority of two edge category experimentally relies on the angle between the stress direction and the crystallographic orientation of MoS₂, also supported by theoretical calculations. We further demonstrate that biaxial stressing MoS₂ crystals could generate an array of well-defined nano-squares, thereby providing a scalable and versatile patterning route to engineer 2D materials with tailored functional edges, which hold great potential for future electrocatalytic and optoelectronic applications.