Point defects are often considered to be detrimental to mesoscopic scale optical and electrical properties of two-dimensional materials. However, when controlled individually in atomic scales, these defects can be used as building blocks for novel quantum information science (QIS) applications. The optically active defects of hexagonal boron nitride and wide bandgap transition metal dichalcogenides have drawn significant interest in recent years due to quantum memory and sensing applications they promise. While the optical properties of host materials and modifications caused by heterogeneities have been widely studied, one to one correlations between the atomic structure of the defects and their role in the optical response of the material are still missing in most cases.   Filling this gap is particularly challenging because the optoelectronic properties of defects are highly sensitive to atomic scale modifications such as local strain and charge transfer landscape around them.  Scanning Tunneling Microscopy (STM) provides a powerful method to investigate the atomic structure of the defects and their influence on the electronic properties of the host lattice.

Using atomic scale imaging and spectroscopy capabilities of STM, we study various 2D materials that host single photon emitter candidates. STM studies help us to understand the atomic origins of photon emission and provide new pathways to control these defects and their optical properties.