CM-AMO Seminar | Revealing Strain and Disorder in Transition-Metal Dichalcogenides Using Hyperspectral Photoluminescence Imaging

Spatial variations in strain and disorder can strongly influence the optical and electronic properties of two-dimensional materials, even when the samples appear uniform under conventional microscopy. In this talk, I will show how hyperspectral photoluminescence imaging can map these variations across complete transition-metal dichalcogenide heterostructures. By recording a densely sampled spectrum at each spatial position, we extract the energies and linewidths of excitons, trions, and biexcitons in hBN-encapsulated MoSe₂ and WSe₂ devices. The resulting maps reveal smooth strain gradients, localized wrinkles and ripples, and changes produced by thermal cycling. In particular, resonance linewidth emerges as a sensitive probe of disorder and unresolved strain variations that may be difficult to identify from photoluminescence intensity or peak energy alone. Measurements across several device architectures and fabrication processes demonstrate how this approach can assess optoelectronic uniformity, identify regions suitable for targeted experiments, and connect device-scale fabrication quality with local excitonic properties.