Microstructure and Elastic Constants of Transition Metal Dichalcogenide Monolayers from Friction and Shear Force Microscopy

TL;DR

This study uses combined microscopy techniques to visualize microstructure and measure elastic constants of CVD-grown WS2 monolayers, aiding the development of optoelectronic devices with a nondestructive, high-throughput approach.

Contribution

It introduces a combined microscopy method to identify microstructural features and experimentally determine elastic constants of TMDC monolayers.

Findings

Grain boundaries, crystal orientation, and strain fields can be visualized unambiguously.

Fourth-order elastic constants of WS2 monolayers are measured experimentally.

The method supports nondestructive, high-throughput analysis for optoelectronic applications.

Abstract

Optical and electrical properties of two-dimensional transition metal dichalcogenides (TMDCs) grown by chemical vapor deposition (CVD) are strongly determined by their microstructure. Consequently, the visualization of spatial structural variations is of paramount importance for future applications. Here we demonstrate how grain boundaries, crystal orientation, and strain fields can unambiguously be identified with combined lateral force microscopy (LFM) and transverse shear microscopy (TSM) for CVD-grown tungsten disulfide (WS2) monolayers, on length scales that are relevant for optoelectronic applications. Further, angle-dependent TSM measurements enable us to acquire the fourth-order elastic constants of monolayer WS2 experimentally. Our results facilitate high-throughput and nondestructive microstructure visualization of monolayer TMDCs, insights into their elastic properties, thus providing an accessible tool to support the development of advanced optoelectronic devices based on such two-dimensional semiconductors.