Energy dispersive X-ray spectroscopy of atomically thin semiconductors

TL;DR

This paper demonstrates the use of energy dispersive X-ray spectroscopy with SEM to accurately analyze the elemental composition and layer number of atomically thin layered semiconductors, including heterostructures.

Contribution

It introduces an optimized EDX technique for layer-resolving analysis of atomically thin transition metal dichalcogenides and heterobilayers, expanding capabilities for 2D material characterization.

Findings

Achieved layer-resolving sensitivity down to monolayers.

Demonstrated elemental profiling in heterobilayers.

Applicable to various 2D layered materials.

Abstract

We report the implementation of energy dispersive X-ray spectroscopy for layered semiconductors in the form of atomically thin transition metal dichalcogenides. The technique is based on a scanning electron microscope equipped with a silicon drift detector for energy dispersive X-ray analysis. By optimizing operational parameters in numerical simulations and experiments, we achieve layer-resolving sensitivity for few-layer crystals down to the monolayer limit and demonstrate elemental composition profiling in vertical and lateral heterobilayers of transition metal dichalcogenides. The technique can be straight-forwardly applied to other layered two-dimensional materials and van der Waals heterostructures, thus expanding the experimental toolbox for quantitative characterization of layer number, atomic composition, or alloy gradients for atomically thin materials and devices.