Dynamical Control of Interlayer Excitons and Trions in WSe$_2$/Mo$_{0.5}$W$_{0.5}$Se$_2$ Heterobilayer via Tunable Near-Field Cavity

Emerging photo-induced excitonic processes in transition metal dichalcogenide (TMD) heterobilayers, e.g., coupling, dephasing, and energy transfer of intra- and inter-layer excitons, allow new opportunities for ultrathin photonic devices. Yet, with the associated large degree of spatial heterogeneity, understanding and controlling their complex competing interactions at the nanoscale remains a challenge. Here, we present an all-round dynamic control of intra- and inter-layer excitonic processes in a WSe$_2$/Mo$_{0.5}$W$_{0.5}$Se$_2$ heterobilayer using multifunctional tip-enhanced photoluminescence (TEPL) spectroscopy. Specifically, we control the radiative recombination path and emission rate, electronic bandgap energy, and neutral to charged exciton conversion with <20 nm spatial resolution in a reversible manner. It is achieved through the tip-induced engineering of Au tip-heterobilayer distance and interlayer distance, GPa scale local pressure, and plasmonic hot-electron injection respectively, with simultaneous spectroscopic TEPL measurements. This unique nano-opto-electro-mechanical control approach provides new strategies for developing versatile nano-excitonic devices based on TMD heterobilayers.

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