Rydberg-like states induced by charged adsorbates on WSe₂

Defects in transition metal dichalcogenides (TMDs) exhibit electronic and optical properties that make them promising candidates for use as single photon emitters and in quantum spin memory architectures, among many other applications. While some TMD defects are predicted to host localized in-gap states, in practice they can be difficult to identify or engineer for desired functionalities. In this talk, we show how deep in-gap states can be engineered by physisorbing charged atomic species onto the surface of WSe₂. The low dielectric environment of the WSe₂ surface enables the formation of large potential wells that traps quasiparticles, leading to the formation of discrete Rydberg-like energy levels. We use scanning probe microscopy to measure the shape of the potential wells that form around the physisorbed atoms and to image the spatial structure and energies of the resulting bound states. Using the scanning probe tip, we deterministically placed the adsorbates into clusters of varying size, creating deeper potential wells and new sets of bound state energy levels. We compare these results to theoretically predicted energy structures and assign bound donor state spectroscopic features to different bands of the WSe₂.