Revealing localized excitons in WSe₂/-Ga₂O₃

We have investigated the optical and magneto-optical properties of monolayer (ML) WSe2 on flakes of beta-Ga2O3 under high magnetic fields. Remarkably, sharp emission peaks were observed and associated with localized excitons related to point defects. A detailed study of low-temperature photoluminescence (PL) and magneto-PL under high perpendicular magnetic field up to 9 T was carried out. Several sharp emission peaks have shown valley g-factors values close to -4, which is an unusual result for localized excitons in WSe2. Furthermore, some PL peaks have shown higher g-factor values of approximate to-7 and approximate to-12, which were associated with the hybridization of strain localized dark excitons and defects. The reported results suggest that beta-Ga2O3 is, indeed, a promising dielectric substrate for ML WSe2 and also to explore fundamental physics in view of possible applications in quantum information technology.