Plasmon–Exciton–Driven Modulation of the Electronic and Optical Properties of MoS ₂ via Cayley Tree Fractal Nanostructures

Two‐dimensional transition metal dichalcogenide (TMD) materials, such as molybdenum disulfide (MoS 2 ), have been explored as potential candidates for the next generation of semiconducting devices. This widespread interest arises from TMD's high transparency, large charge carrier mobility, and tunable electronic structure. One approach of enhancing their performance and modulating their electronic properties can be achieved through the coupling of the exciton modes of the 2D materials with the plasmons modes from a nanostructured metal, thus yielding the formation of an exciton–polariton quasiparticle. In this work, gold fractal patterns were inscribed onto monolayer MoS 2 via electron beam lithography (EBL). A Cayley tree plasmonic structure was selected because it enables versatile control over the plasmon frequency and its matching with the excitonic modes of MoS 2 . The hybrid structure was investigated using a combination of tip‐enhanced Raman spectroscopy (TERS), tip‐enhanced photoluminescence (TEPL), and Kelvin probe force microscopy. These measurements reveal an enhanced photoluminescence and spectral shift in the excitonic modes associated with an increased bandgap and a charge transfer between the plasmonic and excitonic structure.