Photon superbunching in cathodoluminescence of excitons in WS2 monolayer

Cathodoluminescence spectroscopy in conjunction with second-order auto-correlation measurements of g_2(τ) allows to extensively study the synchronization of photon emitters in low-dimensional structures. Co-existing excitons in two-dimensional transition metal dichalcogenide monolayers provide a great source of identical photon emitters which can be simultaneously excited by an electron. Here, we demonstrate large photon bunching with g_2(0) up to 156±16 of a tungsten disulfide monolayer (WS2), exhibiting a strong dependence on the electron-beam current. To further improve the excitation synchronization and the electron-emitter interaction, we show exemplary that the careful selection of a simple and compact geometry - a thin, monocrystalline gold nanodisk - can be used to realize a record-high bunching g_2(0) of up to 2152±236. This approach to control the electron excitation of excitons in a WS2 monolayer allows for the synchronization of photon emitters in an ensemble, which is important to further advance light information and computing technologies.