Organic Molecules as Origin of Visible-Range Single Photon Emission from Hexagonal Boron Nitride and Mica

Abstract

The discovery of room-temperaturesingle-photon emitters(SPEs)hosted by two-dimensional hexagonal boron nitride (2D hBN) has sparkedintense research interest. Although emitters in the vicinity of 2eV have been studied extensively, their microscopic identity has remainedelusive. The discussion of this class of SPEs has centered on pointdefects in the hBN crystal lattice, but none of the candidate defectstructures have been able to capture the great heterogeneity in emitterproperties that is observed experimentally. Employing a widely usedsample preparation protocol but disentangling several confoundingfactors, we demonstrate conclusively that heterogeneous single-photonemission at similar to 2 eV associated with hBN originates from organicmolecules, presumably aromatic fluorophores. The appearance of thoseSPEs depends critically on the presence of organic processing residuesduring sample preparation, and emitters formed during heat treatmentare not located within the hBN crystal as previously thought, butat the hBN/substrate interface. We further demonstrate that the sameclass of SPEs can be observed in a different 2D insulator, fluorophlogopitemica.