Spatially Controlled Single Photon Emitters in hBN-Capped WS2 Domes

Monolayers (MLs) of transition-metal dichalcogenides host efficient single-photon emitters (SPEs) usually associated to the presence of nanoscale mechanical deformations or strain. Large-scale spatial control of strain would enhance the scalability of such SPEs and allow for their incorporation into photonic structures. Here, the formation of regular arrays of strained hydrogen-filled one-layer-thick micro-domes obtained by H-ion irradiation and lithography-based approaches is reported. Typically, the H-2 liquefaction for temperatures T<32 K causes the disappearance of the domes preventing their use as potential SPEs. Here, it is shown that the dome deflation can be overcome by hBN heterostructuring, that is by depositing thin hBN flakes on the domes. This leads to the preservation of the dome structure at all temperatures, as found by micro-Raman and micro-photoluminescence (mu-PL) studies. Eventually, spatially controlled hBN-capped WS2 domes show the appearance, at 5 K, of intense emission lines originating from localized excitons, which are shown to behave as quantum emitters here. The electronic properties of the emitters are addressed by time-resolved mu-PL yielding time decays of 1-10 ns, and by magneto-mu-PL measurements. The latter provide an exciton magnetic moment a factor of two larger than the value observed in planar strain-free MLs.