Single Photon Emitters in Hexagonal Boron Nitride Fabricated by Focused Helium Ion Beam

The 2D layered hexagonal boron nitride (hBN) material is a promising platform for making single photon emitters (SPEs). Integrate SPEs with photonic cavities or waveguides, requires the deterministic positioning of these emitters as accurately as possible. Among all of the alternative techniques, He+ focused ion beam (FIB) theoretically has sub-nanometer precision, but its practical positioning accuracy in processing SPEs is limited by the inevitable detrimental byproduct defects. So far, it remains challenging to achieve an accuracy below 100 nm for the positioning of SPEs in hBN. Here, we present a two-step method for creating SPEs at the predetermined positions in hBN that combines the He+ FIB irradiation and thermal annealing under an oxygen atmosphere. With this method, we have realized the positioning accuracy of less than 50 nm, which, to the best of our knowledge, stands as the highest among the currently available hBN SPEs preparation methods. Moreover, the SPE conversion yield was over 35% and the emission brightness of individual SPE achieved up to 3 x 105 counts/s at room temperature. These SPEs fabricated precisely with nanoscale accuracy in hBN are expected to be good candidates for making large-scale integrated SPEs in photonic circuits. Position-controlled single photon emitters (SPEs) in hBN are demonstrated through a two-step method combining focused helium ion beam (He+ FIB) irradiation with thermal annealing in an oxygen atmosphere. The positioning accuracy of the FIB fabricated pit is less than 50 nm. Moreover, the SPE conversion yield is over 35% and the emission brightness achieved up to 3 x 105 cps at room temperature.image