Synthesis and Characterization of Single Photon Emitters from Chemically Exfoliated Hexagonal Boron Nitride Nanosheets

Single-photon emitters are an essential component in the emerging applications of quantum communication, quantum computing, and integrated quantum photonics. Hexagonal boron nitride (hBN) is of particular interest as a material with a wide bandgap, which allows it to host a wide range of visible to UV emitters and retain stability at room temperature. These emitters arise from spatially isolated defects which introduce mid-gap states which can be excited to act as emitting color centers. In this work, we investigate the properties of single photon emitters in hBN nanosheets, which have been generated by using commercially available hBN powders and intercalating them with molten potassium. Following alkali metal intercalation, hBN was chemically exfoliated in solution and then drop casted onto any substrate. This process introduces a variety of defects embedded in the hBN, in particular, an excess of nitrogen vacancies which has been shown by X-ray photoelectron spectroscopy (XPS). We have found that this system can host bright single photon emitters which are active at room temperature and are stable for months in atmosphere without bleaching or blinking. Through a Hanbury-Brown Twiss Interferometer we have characterized multiple emitters in the range of 570-650 nm with values g2(0)<0.15 without background subtraction, indicating high quality emitters. These findings help to provide insights into the importance of defects in hBN that are responsible for single photon emission, thus opening the possibility for tailoring these defects through chemical functionalization.