Quantum Defect Candidates at Modified Substitution Sites within WS₂

Defect systems with in-gap electronic states are of high interest in atomic-scale photon emission applications with use in, e.g., quantum sensing and quantum networks. We investigate a two-dimensional material system that is treated within an ultrahigh vacuum environment to produce dense regions of chalcogen defectivity [1], and subsequently dope the system with a transition metal of interest that has been selected for its theoretically predicted optical transition and strong transition dipole moment. The chalcogen-substituted defect is formed at the atomic scale via tip-induced diffusion and subsequently visualized with scanning tunnelling microscopy. Scanning tunnelling spectroscopy, collected in an autonomous fashion using Gaussian process regression techniques [2], reveals anticipated in-gap states that are further verified with differential conductance maps paired with simulations obtained by density functional theory. High-throughput defect screening enables the selection of a handful of promising candidates, where the fabrication and investigation of one of these systems is shown to be experimentally obtainable.<br/><br/>References:<br/>[1] Rossi, A., Thomas, J. C. et al. arXiv:2301.02721 (2023)<br/>[2] Thomas, J. C., Rossi, A. et al. npj Comput. Mater. 8, 99 (2022)