Substitutional impurities in monolayer hexagonal boron nitride as single-photon emitters

Single-photon emitters in hexagonal boron nitride have attracted great attention over the last few years due to their excellent optoelectronical properties. Despite the vast range of results reported in the literature, studies on substitutional impurities belonging to the 13th and 15th groups have not been reported yet. Here, through theoretical modeling, we provide direct evidence that hexagonal boron nitride can be opportunely modified by introducing impurity atoms such as aluminum or phosphorus that may work as color centers for single-photon emission. By means of density functional theory, we focus on determining the structural stability, induced strain, and charge states of such defects and discuss their electronic properties. Nitrogen substitutions with heteroatoms of group 15 are shown to provide attractive features (e.g. deep defect levels and localized defect states) for single-photon emission. These results may open up new possibilities for employing innovative quantum emitters based on hexagonal boron nitride for emerging applications in nanophotonics and nanoscale sensing devices.