High-temperature activation of single-photon emitters in monolayer WS2

Abstract Controlled activation of defect-bound excitonic states in two-dimensional semiconductors provides a route to isolated quantum emitters and a sensitive probe of defect physics. Here we demonstrate that in situ high-temperature annealing of hBN-encapsulated monolayer WS2 on a suspended microheater leads to the emergence of spectrally isolated single-photon emitters at cryogenic temperatures. Annealing at temperatures around 1100 K produces a sharp emission line, XL, red-shifted by approximately 80 meV from the neutral exciton and exhibiting a linewidth below 200 µeV. Photoluminescence excitation spectroscopy and power-dependent measurements show that XL originates from annealing-induced defects in the WS2 monolayer, while second-order photon correlation measurements reveal clear antibunching with g (2) (0) < 0.5. These results establish high-temperature in situ annealing as a controlled means to access defect-bound excitonic states and single-photon emission in van der Waals materials.