Revealing Strain and Disorder in Transition-Metal Dichalcogenides Using Hyperspectral Photoluminescence Imaging

TL;DR

Hyperspectral photoluminescence imaging enables detailed spatial mapping of strain and disorder in monolayer transition-metal dichalcogenides, revealing microscopic heterogeneity undetectable by conventional methods.

Contribution

This work introduces hyperspectral PL imaging as a powerful tool for spatially resolving strain and disorder in 2D materials, providing quantitative insights into excitonic features.

Findings

Mapped strain gradients and localized deformations in TMD samples.

Identified regions with uniform optical properties and micro-scale disorder.

Demonstrated the technique's utility across different device architectures.

Abstract

Hyperspectral photoluminescence (HSPL) imaging provides spatially resolved spectral information for monolayer transition-metal dichalcogenides (TMDs), enabling the detection of subtle variations in excitonic features that are not accessible with conventional optical or photoluminescence intensity imaging. We employ HSPL to map the microscopic spatial distribution of strain and disorder in hBN-encapsulated MoSe$_2$ and WSe$_2$ samples. Quantitative extraction of exciton, trion, and biexciton energies and linewidths reveals strain gradients and localized deformations, such as wrinkles and ripples. The technique allows for characterization of regions with uniform optical properties and identification of areas affected by micro-scale disorder, which may be missed by optical microscopy. Measurements on samples with different device architectures and fabrication processes demonstrate the general utility of hyperspectral PL imaging for assessing spatial heterogeneity and optoelectronic quality in two-dimensional materials.